@article{ahn_wang_kim_you_jung_seong_choi_park_choi_kim_2024, title={Catalyst-recirculating system in steam explosion pretreatment for producing high-yield of xylooligosaccharides from oat husk}, volume={342}, ISSN={["1879-1344"]}, DOI={10.1016/j.carbpol.2024.122411}, journal={CARBOHYDRATE POLYMERS}, author={Ahn, Myeong Rok and Wang, Song and Kim, Jonghwa and You, Sang-Mook and Jung, Chan -Duck and Seong, Hyolin and Choi, June -Ho and Park, Sunkyu and Choi, In-Gyu and Kim, Hoyong}, year={2024}, month={Oct} } @article{dey_lower_vook_islam_sagues_han_nimlos_kelley_park_2024, title={Catalytic graphitization of pyrolysis oil for anode application in lithium-ion batteries}, volume={7}, ISSN={["1463-9270"]}, url={https://doi.org/10.1039/D4GC01647E}, DOI={10.1039/d4gc01647e}, abstractNote={The overwhelming demand for lithium-ion batteries necessitates a sustainable and environment-friendly production of graphite anode materials. Catalytic graphitization of pyrolysis oil is promising for mass-scale production of biographite.}, journal={GREEN CHEMISTRY}, author={Dey, Shaikat Chandra and Lower, Lillian and Vook, Trevor and Islam, Md. Nazrul and Sagues, William Joe and Han, Sang-Don and Nimlos, Mark R. and Kelley, Stephen S. and Park, Sunkyu}, year={2024}, month={Jul} } @article{cho_chang_park_2024, title={Effects of hydrogen peroxide and sodium nitrate on microwave-assisted polyethylene oxidative degradation in the presence of nitric acid}, volume={499}, ISSN={["1873-3212"]}, DOI={10.1016/j.cej.2024.155769}, journal={CHEMICAL ENGINEERING JOURNAL}, author={Cho, Seong-Min and Chang, Hou-min and Park, Sunkyu}, year={2024}, month={Nov} } @article{park_yoo_cho_park_cruz_kelley_park_2024, title={Exploring potential of cellulose acetate sulfate films for sustainable packaging: tuning characteristics via sulfate group variation}, volume={1}, ISSN={["1572-882X"]}, DOI={10.1007/s10570-023-05713-8}, journal={CELLULOSE}, author={Park, Seonghyun and Yoo, Seunghyun and Cho, Seong-Min and Park, Hyeonji and Cruz, David and Kelley, Stephen S. and Park, Sunkyu}, year={2024}, month={Jan} } @article{wu_carrejo_reza_woods_razavi_park_li_sagues_2024, title={Kinetic assessment of pulp mill-derived lime mud calcination in high CO2 atmosphere}, volume={373}, ISSN={["1873-7153"]}, url={https://doi.org/10.1016/j.fuel.2024.132372}, DOI={10.1016/j.fuel.2024.132372}, journal={FUEL}, author={Wu, Ruochen and Carrejo, Edgar and Reza, Md Sumon and Woods, Ethan and Razavi, Seyedamin and Park, Sunkyu and Li, Fanxing and Sagues, William Joe}, year={2024}, month={Oct} } @article{lan_cruz_li_boakye_park_tiller_mittal_johnson_park_yao_2024, title={Life-Cycle Assessment of Sustainable Aviation Fuel Derived from Paper Sludge}, volume={12}, ISSN={["2168-0485"]}, url={https://doi.org/10.1021/acssuschemeng.4c00795}, DOI={10.1021/acssuschemeng.4c00795}, abstractNote={Converting waste paper sludge to sustainable aviation fuel (SAF) offers a circular economy strategy to decarbonize the aviation sector. This study develops a life-cycle assessment (LCA) for converting high-ash paper sludge to SAF in the U.S. using a catalytic sugar upgrading system that consists of ash removal, enzymatic hydrolysis, dehydration, aldol condensation, and hydroprocessing. The LCA is coupled with a process simulation for an industrial-scale biorefinery based on experimental data. We quantified the carbon intensity as 35.7–41.8 gCO2eq MJ–1 SAF (−636 to −584 gCO2eq per dry kg paper sludge) with acetone as a solvent, renewable fuel, and biobased chemicals; this is further reduced to 5.1–11.1 gCO2eq MJ–1 (−925 to −873 gCO2eq per dry kg paper sludge) if ash is recycled and used for substituting cement. Converting 1 dry kg paper sludge to SAF with acetone, renewable fuel, and biobased chemicals (−925 to −584 gCO2eq) is more climate beneficial than landfilling without landfill gas recovery (791 gCO2eq) and with landfill gas recovery (−294 gCO2eq). More than 330 million gallons of SAF can be produced annually (>4 million dry t paper sludge/year in the U.S.), resulting in a reduction of 2–7 million tCO2eq.}, number={22}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Lan, Kai and Cruz, David and Li, Jinyue and Boakye, Amma Asantewaa Agyei and Park, Hyeonji and Tiller, Phoenix and Mittal, Ashutosh and Johnson, David K. and Park, Sunkyu and Yao, Yuan}, year={2024}, month={Apr}, pages={8379–8390} } @article{dey_worfolk_lower_sagues_nimlos_kelley_park_2024, title={Phenolic Resin Derived Hard Carbon Anode for Sodium-Ion Batteries: A Review}, volume={5}, ISSN={["2380-8195"]}, url={https://doi.org/10.1021/acsenergylett.4c00688}, DOI={10.1021/acsenergylett.4c00688}, abstractNote={Sodium-ion batteries are complementary to lithium-ion batteries for grid-scale energy storage applications due to lower cost, safety, and potential for sustainable supply chains. The past decade has witnessed enormous research efforts in developing hard carbon anode materials for sodium-ion batteries. Phenolic resins have received significant attention as hard carbon precursors due to their high carbon yield, highly cross-linked structure, low cost, mature technology, and excellent electrochemical performance of corresponding hard carbon anode. This Review exclusively highlights the state-of-the-art preparation of hard carbon from phenolic resins, and the electrochemical performance in sodium-ion batteries. Cross-linked resins are prepared from three phenolic monomers (phenol, resorcinol, and phloroglucinol) to produce hard carbon. The effects of carbonization temperature on the microstructure, and electrochemical properties of hard carbon have been summarized here. Hard carbon formation, and sodium storage mechanisms have been briefly outlined. Finally, this Review provides an industrial perspective on hard carbon production at scale.}, journal={ACS ENERGY LETTERS}, author={Dey, Shaikat Chandra and Worfolk, Brian and Lower, Lillian and Sagues, William Joe and Nimlos, Mark R. and Kelley, Stephen S. and Park, Sunkyu}, year={2024}, month={May} } @article{dulger_yuan_singh_omolabake_czarnecki_nikafshar_li_becsy-jakab_park_park_et al._2024, title={Scale-Up of a Two-Stage Cu-Catalyzed Alkaline-Oxidative Pretreatment of Hybrid Poplar}, volume={3}, ISSN={["1520-5045"]}, DOI={10.1021/acs.iecr.3c04466}, abstractNote={A two-stage alkaline-oxidative pretreatment of hybrid poplar was investigated at scale (20 L reactor volume) with the goal of understanding how reaction conditions as well as interstage mechanical refining impact downstream process responses. The pretreatment comprises a first stage of alkaline delignification (alkaline pre-extraction) followed by a second delignification stage employing Cu-catalyzed alkaline hydrogen peroxide with supplemental O2 (O2-enhanced Cu-AHP). Increasing pre-extraction severity (i.e., temperature and alkali loading) and pretreatment oxidation (increasing H2O2 loading) were found to increase mass and lignin solubilization in each stage. Lignin recovered from the first stage was subjected to oxidative depolymerization and led to aromatic monomer yields as high as 23.0% by mass. Lignins recovered from the second-stage Cu-AHP pretreatment liquors were shown to exhibit aliphatic hydroxyl contents more than 6-fold higher than a typical hardwood kraft lignin, indicating that these lignins could serve as a biobased polyol for a range of polyurethane applications.}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Dulger, Dilara N. and Yuan, Zhaoyang and Singh, Sandip K. and Omolabake, Surajudeen and Czarnecki, Celeste R. and Nikafshar, Saeid and Li, Mingfei and Becsy-Jakab, Villo E. and Park, Seonghyun and Park, Sunkyu and et al.}, year={2024}, month={Mar} } @article{park_sharmin_cho_kelley_shirwaiker_park_2024, title={Single-Component Cellulose Acetate Sulfate Hydrogels for Direct Ink Writing 3D Printing}, volume={8}, ISSN={["1526-4602"]}, url={https://pubs.acs.org/doi/full/10.1021/acs.biomac.4c00578}, DOI={10.1021/acs.biomac.4c00578}, abstractNote={Hydrogels, typically favored for 3D printing due to their viscoelasticity, are now trending toward ecofriendly alternatives amid growing environmental concerns. In this study, we crafted cellulose-based hydrogels, specifically employing cellulose acetate sulfate (CAS). By keeping the acetyl group substitution degree (DS}, journal={BIOMACROMOLECULES}, author={Park, Seonghyun and Sharmin, Tavila and Cho, Seong-Min and Kelley, Stephen S. and Shirwaiker, Rohan A. and Park, Sunkyu}, year={2024}, month={Aug} } @article{tiller_park_cruz_carrejo_johnson_mittal_venditti_park_2024, title={Techno-economic analysis of biomass value-added processing informed by pilot scale de-ashing of paper sludge feedstock}, volume={401}, ISSN={["1873-2976"]}, url={http://dx.doi.org/10.1016/j.biortech.2024.130744}, DOI={10.1016/j.biortech.2024.130744}, journal={BIORESOURCE TECHNOLOGY}, author={Tiller, Phoenix and Park, Hyeonji and Cruz, David and Carrejo, Edgar and Johnson, David K. and Mittal, Ashutosh and Venditti, Richard and Park, Sunkyu}, year={2024}, month={Jun} } @article{park_rahmani_treasure_lee_tiller_pasquinelli_kelley_park_2024, title={Understanding the formation of insoluble gel particles during cellulose diacetate production}, volume={2}, ISSN={["1572-882X"]}, url={http://dx.doi.org/10.1007/s10570-024-05769-0}, DOI={10.1007/s10570-024-05769-0}, journal={CELLULOSE}, author={Park, Seonghyun and Rahmani, Farzin and Treasure, Trevor and Lee, Joo and Tiller, Phoenix and Pasquinelli, Melissa A. and Kelley, Stephen S. and Park, Sunkyu}, year={2024}, month={Feb} } @article{molina_park_park_kelley_2023, title={Effective toluene removal from aqueous solutions using fast pyrolysis-derived activated carbon from agricultural and forest residues: Isotherms and kinetics study}, volume={9}, ISSN={["2405-8440"]}, url={https://doi.org/10.1016/j.heliyon.2023.e15765}, DOI={10.1016/j.heliyon.2023.e15765}, abstractNote={In this study, the production and characterization of activated carbons (ACs) from agricultural and forest residue using physical activation are discussed. Biomass-based biochars produced during fast pyrolysis process is introduced as alternative precursors to produce AC and the integrated process for the co-production of porous adsorbent materials from biochar via the fast pyrolysis process is suggested. Moderate surface areas and good adsorption capacities were obtained from switchgrass (SWG) and pine tops (PT) based AC. The surface areas were 959 and 714 m2/g for SWG- and PT-based AC, respectively. The adsorption capacities using toluene as pollutant for two model systems of 180 and 300 ppm were measured and ranged between 441-711 and 432-716 mg/g for SWG-based and PT-based AC, respectively. The nitrogen adsorptive behavior, Lagergren pseudo-second-order kinetic (PSOK) model and kinetics isotherms studies describe a heterogeneous porous system, including a mesoporous fraction with the existence of a multilayer adsorption performance. The presence of micropores and mesopores in SWG- and PT-based AC suggests potential commercial applications for using pyrolytic biochars for AC production.}, number={5}, journal={HELIYON}, author={Molina, Eliezer A. Reyes and Park, Seonghyun and Park, Sunkyu and Kelley, Stephen S.}, year={2023}, month={May} } @article{molina_vook_sagues_kim_labbe_park_kelley_2023, title={Green Needle Coke Production from Pyrolysis Biocrude toward Bio-based Anode Material Manufacture: Biochar Fines Addition Effect as ?Physical Template? on the Crystalline Order}, volume={11}, ISSN={["2168-0485"]}, url={https://doi.org/10.1021/acssuschemeng.2c06952}, DOI={10.1021/acssuschemeng.2c06952}, abstractNote={A new method for producing green needle coke (GNC) is developed by replacing the "heavy fraction" of petroleum pitch delayed coking with fast pyrolysis biocrude. A series of alternative biocrude distillation, carbonization, and calcination conditions were investigated to determine the influence of these processing parameters onto the crystalline structure of the resulting graphitized material. For the first time, the addition of biochar fines was found to serve as a "physical template" to increase the graphitic nature of the final product. During the initial biocrude carbonization (350–450 °C), volatile compounds are released, and aromatics in pyrolysis biocrude experience condensation, resulting in GNC solids with carbon contents above 95 wt % and some early lamellar structure. In the second stage of the thermal process (25–1500 °C), there are additional thermal decomposition reactions with an increase in the aromatic nature of the graphitized solid. It was found that systematic addition of biochar fines induces a nucleating effect during the GNC development. Thermogravimetric analysis suggests that biochar fines promote polycondensation reactions by modifying the biopitch structure and molecular weight, while elemental analysis (CHN) shows a reduction in both H/C and O/C ratios which are consistent with the increase in aromaticity and removal of oxygenated compounds as thermal treatment evolves. The effects of different bio-based pitch materials (after distillation) and GNC intermediates were evaluated by pyrolysis-gas chromatography mass spectrometry and Fourier transform infrared, displaying slight changes on product yields and quality. X-ray diffraction patterns taken after graphitization evidence an increase in the graphitic order with the addition of biochar fines. Transmittance electron microscopy depicts an improvement on graphitic morphology as biochar fine content increases. The use of biochar fines showed a significant increase in graphitic ordering at addition levels above 0.01 wt %. These results show that thermally treated biocrude/biochar fine systems can produce graphitic structures (hard carbon-like) that might be suitable for the manufacture of sodium-ion batteries.}, number={18}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Molina, Eliezer A. Reyes and Vook, Trevor and Sagues, William J. and Kim, Keonhee and Labbe, Nicole and Park, Sunkyu and Kelley, Stephen S.}, year={2023}, month={May}, pages={6944–6955} } @article{xu_rios_wang_ham_choi_kim_park_2024, title={Process design and techno-economic analysis for the lignin oil solvent recovery and purification process}, volume={434}, ISSN={["1879-1786"]}, url={http://dx.doi.org/10.1016/j.jclepro.2023.139999}, DOI={10.1016/j.jclepro.2023.139999}, abstractNote={A technology to extract lignin oil from pretreated biomass has been developed for a cosmetic additive application (i.e., UV protection) through isopropyl alcohol without any catalyst. It was used for co-product lignin oil with XOS from a biorefinery process in this study. One of the key factors impacting economic feasibility is extraction solvent recovery, and it is important to design the process details based on techno-economic analysis. Therefore, this study has integrated lab experiments, process designs with Aspen Plus process simulations, and Excel-based techno-economic analysis to investigate the effect of solvent recovery on overall economics. Three options for solvent recovery (e.g., distillation, salting-out, and molecular sieve) have been explored. The salting-out method showed the best economic performance with an IRR of 33.6%, while the distillation method was 21.7% and the molecular sieve method was 16.7%. Key parameters are also identified by sensitivity analyses, which indicate the improvement potential for each case. This study has laid a foundation for lignin oil production studies, but its concept and approach can be applied to any solvent recycling in a biorefinery process, which is often neglected in lab-scale biorefinery studies.}, journal={JOURNAL OF CLEANER PRODUCTION}, author={Xu, Yiling and Rios, David Cruz and Wang, Song and Ham, Choonghyun and Choi, June-Ho and Kim, Hoyong and Park, Sunkyu}, year={2024}, month={Jan} } @article{park_yoo_cho_kelley_park_2023, title={Production of single-component cellulose-based hydrogel and its utilization as adsorbent for aqueous contaminants}, volume={243}, ISSN={["1879-0003"]}, DOI={10.1016/j.ijbiomac.2023.125085}, abstractNote={The growing concern for the environment has resulted in renewed interest in bio-based resources. This study aims to produce a hydrogel adsorbent from cellulose and examine its adsorption performance. In pursuit of this goal, we report a simple one-pot synthesis of cellulose acetate sulfate (CAS), followed by the formation of CAS hydrogels and their subsequent adsorption performances. The CAS includes both hydrophilic and hydrophobic functional groups, enable the formation of a single-component hydrogel through intermolecular interactions in deionized water. The thermal reversibility of CAS hydrogels makes them easily processable into various shapes. The durability of the CAS hydrogel adsorbents can be improved by introducing divalent cations (e.g., Ca2+), which create ionically crosslinked hydrogels. The ionically a crosslinked CAS hydrogel adsorbent exhibits a maximum adsorption capacity of 245 mg/g for methylene blue (MB) at 23 °C and a pH of 7. The adsorption behavior of MB on the CAS hydrogel follows both the pseudo-second-order model and the Langmuir adsorption isotherm model. Furthermore, the CAS hydrogel adsorbent maintains a 70 % removal ratio after five cycles. The simplicity of synthesis and hydrogel formation opens up new possibilities for producing and utilizing cellulose-based hydrogels as adsorbents for aqueous contaminants.}, journal={INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES}, author={Park, Seonghyun and Yoo, Seunghyun and Cho, Seong-Min and Kelley, Stephen S. and Park, Sunkyu}, year={2023}, month={Jul} } @article{vook_dey_yang_nimlos_park_han_sagues_2023, title={Sustainable Li-ion anode material from Fe-catalyzed graphitization of paper waste}, volume={73}, ISSN={["2352-1538"]}, url={https://doi.org/10.1016/j.est.2023.109242}, DOI={10.1016/j.est.2023.109242}, abstractNote={A novel method for the conversion of paper towel waste to biographite anode material is developed and optimized for use in Li-ion batteries. The surge in demand for Li-ion battery anode materials coupled with the unsustainable and inefficient methods of producing battery-grade graphite necessitate alternative carbon feedstocks and graphitization technologies. Paper waste (PW) is identified as a suitable carbon feedstock for iron-catalyzed graphitization due to its sustainability, low cost, low ash content, and ample supply for the intended end use. A Box Behnken experimental design for statistical optimization is pursued for untreated and pre‑carbonized PW with factors of temperature (1100–1300 °C), hold time (1–5 h), and iron catalyst loading (0.5–1.5× fixed carbon content) with biographite crystal size as the primary response variable. Temperature and iron catalyst loading are found to be significant factors, whereas hold time is found to be insignificant. Reversible capacities of the biographite anodes are found to be 340–355 mAh g−1 with 99 % capacity retention over 100 cycles, indicating good electrochemical performance relative to commercial graphite anodes. The initial Coulombic efficiency of untreated and pre‑carbonized biographites, however, are 77 % and 75 %, respectively, suggesting parasitic reactions including electrolyte decomposition.}, journal={JOURNAL OF ENERGY STORAGE}, author={Vook, Trevor and Dey, Shaikat Chandra and Yang, Junghoon and Nimlos, Mark and Park, Sunkyu and Han, Sang-Don and Sagues, William Joe}, year={2023}, month={Dec} } @article{park_cruz_tiller_johnson_mittal_jameel_venditti_park_2022, title={Effect of ash in paper sludge on enzymatic hydrolysis}, volume={165}, ISSN={0961-9534}, url={http://dx.doi.org/10.1016/j.biombioe.2022.106567}, DOI={10.1016/j.biombioe.2022.106567}, abstractNote={The valorization of paper sludge is a high-potential process to develop renewable fuels and chemicals, which can be integrated with pulp and paper mills. Calcium carbonate is the main ash component in sludge, which plays a role in buffering pH and potentially lowering the conversion during enzymatic hydrolysis. Therefore, it is important to investigate the effect of ash on sugar yields and examine pH change to introduce efficient and economical enzymatic hydrolysis of sludge. Carbohydrate conversion was enhanced when the ash was removed by fractionation. On the other hand, the highest sugar recovery was obtained when the sludge contained 20% ash content. The pH change during enzymatic hydrolysis was influenced by ash and explained why sludge-derived hydrolysate showed lower carbohydrate conversion. Therefore, a high shear process with the increased acid amount is suggested to prohibit the negative effect of ash and enhance the accessibility of cellulase to fibers. This study highlights the feasibility of using wet waste streams generated by the paper industry.}, journal={Biomass and Bioenergy}, publisher={Elsevier BV}, author={Park, Hyeonji and Cruz, David and Tiller, Phoenix and Johnson, David K. and Mittal, Ashutosh and Jameel, Hasan and Venditti, Richard and Park, Sunkyu}, year={2022}, month={Oct}, pages={106567} } @article{miller_wang_gardner_venditti_park_2022, title={Toughened Renewable Bio-polyester Blends Achieved through Crystallization Retardation by Acetylated Cellulose Fibers}, volume={12}, ISSN={["2637-6105"]}, DOI={10.1021/acsapm.2c01725}, abstractNote={Acetylation was explored as a technique to make cellulose fibers more compatible within a poly(lactic acid)/poly(3-hydroxybutyrate) polymer matrix. Acetylation was performed to degrees of substitutions 1.74, 2.52, and 2.8, and fibers were used in loadings from 0–20% by weight. Results showed no tensile strength improvements due to poor dispersion and fiber size reduction with fiber addition, but there were increases in modulus in the non-acetylated fiber sample and fully acetylated [degree of substitution (DS) 2.8] fiber samples. Composites containing modified fibers showed an increase in strain at break by as much as 200% at low loading levels. Acetylated cellulose acted as a nucleation retardant, while unmodified cellulose fibers acted as a nucleating agent. Results indicated the importance of fiber size, fiber, dispersion, and fiber–polymer interactions for final properties. Acetylated fiber reinforcement showed some promise for increasing maximum strain and compatibility of composites, which could allow for future investigations into filler chemistry–final property relationships, especially in applications like 3D printing where increased toughness is desired for some polymers.}, journal={ACS APPLIED POLYMER MATERIALS}, author={Miller, A. Griffin and Wang, Lu and Gardner, Douglas and Venditti, Richard A. and Park, Sunkyu}, year={2022}, month={Dec} } @article{kim_sriram_fang_kelley_park_2021, title={An eco-friendly approach for blending of fast-pyrolysis bio-oil in petroleum-derived fuel by controlling ash content of loblolly pine}, volume={179}, ISSN={["1879-0682"]}, DOI={10.1016/j.renene.2021.08.033}, abstractNote={This paper describes the effect of the ash content in biomass on the distribution of pyrolysis products and the miscibility of bio-oil in diesel. Ash content of loblolly pine wood (0.5 wt %, 1.1 wt %, and 1.5 wt %) was systematically varied by impregnating the wood with potassium carbonate solution. Variation in the ash content did not create a significant change in the chemical composition of the impregnated biomass. However, the response to a variety of thermal treatments changed significantly. The volatile matter content decreased from 88.3% to 78.2%, while the bio-oil yield declined from 45.7% to 29.9% as the ash content increased. Although the total organic yield decreased with increased biomass ash content, the total concentration of phenolic monomers increased from 2.8 mg/g to 20.2 mg/g, and bio-oil miscibility with a commercial diesel fuel increased from 6.7% to 13.4% based on wet bio-oil. The miscibility of guaiacol and 4-methyl guaiacol in diesel was higher than that of catechol, due to the lower polar and hydrogen bonding contribution. Test in a diesel engine showed a simultaneous reduction of HC and NOx emissions using diesel extracts.}, journal={RENEWABLE ENERGY}, author={Kim, Hoyong and Sriram, Subash and Fang, Tiegang and Kelley, Stephen and Park, Sunkyu}, year={2021}, month={Dec}, pages={2063–2070} } @article{lan_ou_park_kelley_nepal_kwon_cai_yao_2021, title={Dynamic life-cycle carbon analysis for fast pyrolysis biofuel produced from pine residues: implications of carbon temporal effects}, volume={14}, ISSN={["1754-6834"]}, url={https://doi.org/10.1186/s13068-021-02027-4}, DOI={10.1186/s13068-021-02027-4}, abstractNote={Abstract Background Woody biomass has been considered as a promising feedstock for biofuel production via thermochemical conversion technologies such as fast pyrolysis. Extensive Life Cycle Assessment studies have been completed to evaluate the carbon intensity of woody biomass-derived biofuels via fast pyrolysis. However, most studies assumed that woody biomass such as forest residues is a carbon–neutral feedstock like annual crops, despite a distinctive timeframe it takes to grow woody biomass. Besides, few studies have investigated the impacts of forest dynamics and the temporal effects of carbon on the overall carbon intensity of woody-derived biofuels. This study addressed such gaps by developing a life-cycle carbon analysis framework integrating dynamic modeling for forest and biorefinery systems with a time-based discounted Global Warming Potential (GWP) method developed in this work. The framework analyzed dynamic carbon and energy flows of a supply chain for biofuel production from pine residues via fast pyrolysis. Results The mean carbon intensity of biofuel given by Monte Carlo simulation across three pine growth cases ranges from 40.8–41.2 g CO2e MJ−1 (static method) to 51.0–65.2 g CO2e MJ−1 (using the time-based discounted GWP method) when combusting biochar for energy recovery. If biochar is utilized as soil amendment, the carbon intensity reduces to 19.0–19.7 g CO2e MJ−1 (static method) and 29.6–43.4 g CO2e MJ−1 in the time-based method. Forest growth and yields (controlled by forest management strategies) show more significant impacts on biofuel carbon intensity when the temporal effect of carbon is taken into consideration. Variation in forest operations and management (e.g., energy consumption of thinning and harvesting), on the other hand, has little impact on the biofuel carbon intensity. Conclusions The carbon temporal effect, particularly the time lag of carbon sequestration during pine growth, has direct impacts on the carbon intensity of biofuels produced from pine residues from a stand-level pine growth and management point of view. The carbon implications are also significantly impacted by the assumptions of biochar end-of-life cases and forest management strategies. }, number={1}, journal={BIOTECHNOLOGY FOR BIOFUELS}, publisher={Springer Science and Business Media LLC}, author={Lan, Kai and Ou, Longwen and Park, Sunkyu and Kelley, Stephen S. and Nepal, Prakash and Kwon, Hoyoung and Cai, Hao and Yao, Yuan}, year={2021}, month={Sep} } @article{zeng_jang_park_park_kan_2021, title={Effects of Mechanical Refining on Anaerobic Digestion of Dairy Manure}, volume={6}, ISSN={["2470-1343"]}, DOI={10.1021/acsomega.1c01760}, abstractNote={Mechanical refining (MR) is a cost-effective pretreatment in biochemical conversion processes that is employed to overcome biomass recalcitrance. This work studied the effects of MR on biogas and methane produced by the anaerobic digestion (AD) of dairy manure. The cumulative gas volume and yield from the AD of manure refined at 6k revolutions increased by 33.7 and 7.7% for methane and by 32.0 and 6.4% for biogas, respectively, compared to the unrefined manure. This enhancement was reached by increasing manure solubilization, reducing particle size, and achieving external fibrillation and internal delamination of fibers in manure. However, the highly refined manure (subjected to 60k revolutions) exhibited methane and biogas yields that were reduced by 9.5 and 1.5%, respectively. This decrease was observed because the pore structure was ruptured, and finely ground manure particles were aggregated together at high revolutions (60k), thereby inhibiting the release of organic matter from the manure. Therefore, this study indicates that the MR for pretreatment of dairy manure could have great potential for significantly enhancing AD of dairy manure. Further studies will include optimization of conditions of mechanical refining (i.e., mechanical intensity, process time), a continuous AD of dairy manure pretreated by the MR, and scale-up with cost evaluation.}, number={26}, journal={ACS OMEGA}, author={Zeng, Shengquan and Jang, Hyun Min and Park, Seonghyun and Park, Sunkyu and Kan, Eunsung}, year={2021}, month={Jul}, pages={16934–16942} } @article{lan_ou_park_kelley_english_yu_larson_yao_2021, title={Techno-Economic Analysis of decentralized preprocessing systems for fast pyrolysis biorefineries with blended feedstocks in the southeastern United States}, volume={143}, ISSN={["1879-0690"]}, url={https://doi.org/10.1016/j.rser.2021.110881}, DOI={10.1016/j.rser.2021.110881}, abstractNote={This study evaluated the economic feasibility of fast pyrolysis biorefineries fed with blended pine residues and switchgrass in the Southeastern U.S. with different supply chain design. Previous techno-economic analyses (TEA) have focused on either blended biomass or decentralized preprocessing without investigating the impacts of varied process parameters, technology options, and real-world biomass distribution. This study fills the literature gap by modeling scenarios for different biomass blending ratios, biorefinery and preprocessing site (so-called depot) capacities, and alternative preprocessing technologies. High-resolution, real-world geospatial data were analyzed using Geographic Information Systems to facilitate supply chain design and TEA. For a decentralized system, the minimum fuel selling price (MFSP) of biofuel was $3.92–$4.33 per gallon gasoline equivalent (GGE), while the MFSP for the centralized biorefinery at the same capacities ranged between $3.75–$4.02/GGE. Implementing a high moisture pelleting process depot rather than a conventional pelleting process lowered the MFSP by $0.03–$0.17/GGE. Scenario analysis indicated decreased MFSP with increasing biorefinery capacities but not necessarily with increasing depot size. Medium-size depots (500 OMDT/day) achieved the lowest MFSP. This analysis identified the optimal blending ratios for two preprocessing technologies at varied depot sizes. Counterintuitively, increasing the proportion of higher cost switchgrass reduced the MFSP for large biorefineries (>5000 ODMT/day), but increased the MFSP for small biorefineries (1000–2500 ODMT/day). Although the decentralized systems have a higher MFSP based on current analysis, it has other potential benefits such as mitigated supply chain risks and improved feedstock quality that are difficult to be quantified in this TEA.}, journal={RENEWABLE & SUSTAINABLE ENERGY REVIEWS}, publisher={Elsevier BV}, author={Lan, Kai and Ou, Longwen and Park, Sunkyu and Kelley, Stephen S. and English, Burton C. and Yu, T. Edward and Larson, James and Yao, Yuan}, year={2021}, month={Jun} } @article{lan_xu_kim_ham_kelley_park_2021, title={Techno-economic analysis of producing xylo-oligosaccharides and cellulose microfibers from lignocellulosic biomass}, volume={340}, ISSN={["1873-2976"]}, url={http://dx.doi.org/10.1016/j.biortech.2021.125726}, DOI={10.1016/j.biortech.2021.125726}, abstractNote={This study assesses the economic performance of a biorefinery producing xylo-oligosaccharides (XOS) from miscanthus by autohydrolysis and purification based on a rigorous model developed in ASPEN Plus. Varied biorefinery capacities (50-250 oven dry metric ton (ODMT)/day) and three XOS content levels (80%, 90%, 95%) are analyzed. The XOS minimum selling price (XOS MSP) is varied between $3,430-$7,500, $4,030-$8,970, and $4,840-$10,640 per metric ton (MT) for 80%, 90%, and 95% content, respectively. The results show that increasing biorefinery capacity can significantly reduce the XOS MSP and higher purity leads to higher XOS MSP due to less yield, and higher capital and operating costs. This study also explores another system configuration to produce high-value byproducts, cellulose microfiber, by utilizing the cellulose to produce microfiber instead of combusting for energy recovery. The XOS MSP of cellulose microfiber case is $2,460-$7,040/MT and thus exhibits potential economic benefits over the other cases.}, journal={BIORESOURCE TECHNOLOGY}, publisher={Elsevier BV}, author={Lan, Kai and Xu, Yiling and Kim, Hoyong and Ham, Choonghyun and Kelley, Stephen S. and Park, Sunkyu}, year={2021}, month={Nov} } @article{sagues_yang_monroe_han_vinzant_yung_jameel_nimlos_park_2020, title={A simple method for producing bio-based anode materials for lithium-ion batteries}, volume={22}, url={http://dx.doi.org/10.1039/d0gc02286a}, DOI={10.1039/d0gc02286a}, abstractNote={Renewable biomaterials are catalytically converted to graphite for use in lithium-ion anodes using a simple and scalable process.}, number={20}, journal={Green Chemistry}, publisher={Royal Society of Chemistry (RSC)}, author={Sagues, William and Yang, Junghoon and Monroe, Nicholas and Han, Sang-Don and Vinzant, Todd and Yung, Matthew and Jameel, Hasan and Nimlos, Mark and Park, Sunkyu}, year={2020}, pages={7093–7108} } @article{sagues_jameel_sanchez_park_2020, title={Prospects for bioenergy with carbon capture & storage (BECCS) in the United States pulp and paper industry}, volume={13}, url={http://dx.doi.org/10.1039/d0ee01107j}, DOI={10.1039/d0ee01107j}, abstractNote={The pulp and paper industry is a suitable candidate to lead the deployment of BECCS in the US.}, number={8}, journal={Energy & Environmental Science}, publisher={Royal Society of Chemistry (RSC)}, author={Sagues, William and Jameel, H. and Sanchez, Daniel and Park, Sunkyu}, year={2020}, pages={2243–2261} } @article{ou_dou_yu_kim_park_lee_kelley_park_2021, title={Techno-economic analysis of sugar production from lignocellulosic biomass with utilization of hemicellulose and lignin for high-value co-products}, volume={15}, ISSN={["1932-1031"]}, DOI={10.1002/bbb.2170}, abstractNote={AbstractSugar derived from lignocellulosic biomass is an important intermediate product, often used for the production of biofuels and value‐added chemicals. It is therefore essential to understand and reduce the production costs of sugar derived from lignocellulosic biomass. This study evaluates the economic feasibility of a biorefinery producing sugar from lignocellulosic biomass using a combination of autohydrolysis and mechanical refining pretreatment. This biorefinery is self‐sufficient in energy, producing excess electricity for sale. The minimum sugar selling price (MSSP) that achieves a zero net present value is $446/metric ton. The possibility of using the two main by‐products, dissolved hemicellulose and lignin, for the production of high‐value products, xylitol and polyol, is also evaluated. When dissolved hemicellulose is used for xylitol production, the MSSP decreases to $347/metric ton. When lignin is liquefied to produce polyol, the MSSP is further reduced to $342/metric ton. External energy (natural gas) must be purchased if xylitol and polyol are produced. An analysis of capital and operating costs reveals that, although the production of xylitol and polyol incurs additional capital investment, their correspondingly high values outweigh the additional capital costs. Sensitivity analysis results indicate that efficient recovery and recycling of expensive chemicals like acetone and glycerol are key to the success of the biorefinery. Yields of xylitol and polyol also have strong impacts on the process economics. © 2020 Society of Industrial Chemistry and John Wiley & Sons Ltd}, number={2}, journal={BIOFUELS BIOPRODUCTS & BIOREFINING-BIOFPR}, author={Ou, Longwen and Dou, Chang and Yu, Ju-Hyun and Kim, Hoyong and Park, Yong-Cheol and Lee, Eun Yeol and Kelley, Stephen and Park, Sunkyu}, year={2021}, month={Mar}, pages={404–415} } @article{jiang_narron_han_park_chang_jameel_2020, title={Tracing Sweetgum Lignin's Molecular Properties through Biorefinery Processing}, volume={13}, ISSN={["1864-564X"]}, DOI={10.1002/cssc.202001125}, abstractNote={AbstractChanges to the molecular properties of lignin over the course of biorefinery processing were investigated by using sweetgum as a feedstock. Hydrothermal pretreatment has been used because it is an economically attractive, green process. Three representative biorefinery lignin preparations were obtained, with about 70 % yield based on raw lignin. The three fractions included soluble lignin adsorbed on resin (XADL), solvent‐extracted lignin (HTCELp), and an additional ball‐milled residual lignin (HTRELp). By comparing the raw and biorefinery lignin preparations, it can be concluded that lignin undergoes both degradation and condensation throughout the various stages of the hydrothermal‐based biorefinery process. The two fractions made soluble by biorefinery processing, XADL and HTCELp, were found to be low‐molecular‐weight degradation products enriched with free phenolic hydroxyl groups. In addition, about 15 % of noncondensed phenolic units were involved in condensation reactions. Quantitative NMR spectroscopy analysis revealed that at least about 28 % of β‐O‐4′ substructures were cleaved. Hibbert's ketones were identified in XADL and HTRELp, which provided evidence of lignin undergoing acidolysis. The contents of β‐5′ and β‐β′ did not change significantly upon biorefinery processing. Finally, episyringaresinol was detected in XADL and HTCELp. It is hoped that these findings will help to further demonstrate the specific effects of biorefinery processing on lignin in hardwood and facilitate its utilization to improve biorefinery economics.}, number={17}, journal={CHEMSUSCHEM}, author={Jiang, Xiao and Narron, Robert H. and Han, Qiang and Park, Sunkyu and Chang, Hou-min and Jameel, Hasan}, year={2020}, month={Sep}, pages={4613–4623} } @article{ghorbannezhad_park_onwudili_2020, title={Co-pyrolysis of biomass and plastic waste over zeolite- and sodium-based catalysts for enhanced yields of hydrocarbon products}, volume={102}, ISSN={0956-053X}, url={http://dx.doi.org/10.1016/j.wasman.2019.12.006}, DOI={10.1016/j.wasman.2019.12.006}, abstractNote={Ex-situ co-pyrolysis of sugarcane bagasse pith and polyethylene terephthalate (PET) was investigated over zeolite-based catalysts using a tandem micro-reactor at an optimised temperature of 700 °C. A combination of zeolite (HZSM-5) and sodium carbonate/gamma-alumina served as effective catalysts for 18% more oxygen removal than HZSM-5 alone. The combined catalysts led to improved yields of aromatic (8.7%) and olefinic (6.9%) compounds. Carbon yields of 20.3% total aromatics, 18.3% BTXE (benzene, toluene, xylenes and ethylbenzene), 17% olefins, and 7% phenols were achieved under optimal conditions of 700 °C, a pith (biomass) to PET ratio of 4 and an HZSM-5 to sodium carbonate/gamma-alumina ratio of 5. The catalytic presence of sodium prevented coke formation, which has been a major cause of deactivation of zeolite catalysts during co-pyrolysis of biomass and plastics. This finding indicates that the catalyst combination as well as biomass/plastic mixtures used in this work can lead to both high yields of valuable aromatic chemicals and potentially, extended catalyst life time.}, journal={Waste Management}, publisher={Elsevier BV}, author={Ghorbannezhad, Payam and Park, Sunkyu and Onwudili, Jude A.}, year={2020}, month={Feb}, pages={909–918} } @article{sagues_assis_hah_sanchez_johnson_acharya_jameel_park_2020, title={Decarbonizing agriculture through the conversion of animal manure to dietary protein and ammonia fertilizer}, volume={297}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2019.122493}, abstractNote={The decarbonization of agriculture faces many challenges and has received a level of attention insufficient to abate the worst effects of climate change and ensure a sustainable bioeconomy. Agricultural emissions are caused both by fossil-intensive fertilizer use and land-use change, which in turn are driven in part by increasing demand for dietary protein. To address this challenge, we present a synergistic system in which organic waste-derived biogas (a mixture of methane and carbon dioxide) is converted to dietary protein and ammonia fertilizer. This system produces low-carbon fertilizer inputs alongside high-quality protein, addressing the primary drivers of agricultural emissions. If the proposed system were implemented across the United States utilizing readily available organic waste from municipal wastewater, landfills, animal manure, and commercial operations, we estimate 30% of dietary protein intake and 127% of ammonia usage could be displaced while reducing land use, water consumption, and greenhouse gas emissions.}, journal={BIORESOURCE TECHNOLOGY}, publisher={Elsevier BV}, author={Sagues, William J. and Assis, Camilla A. and Hah, Phillip and Sanchez, Daniel L. and Johnson, Zackary and Acharya, Madhav and Jameel, Hasan and Park, Sunkyu}, year={2020}, month={Feb} } @article{jung_sharma-shivappa_park_kolar_2020, title={Effect of cellulolytic enzyme binding on lignin isolated from alkali and acid pretreated switchgrass on enzymatic hydrolysis}, volume={10}, ISSN={["2190-5738"]}, DOI={10.1007/s13205-019-1978-z}, abstractNote={In this research, the binding of cellulolytic enzymes in Cellic ® CTec2 on six lignin isolates obtained from alkali (0.5, 1.0, and 1.5% NaOH at 121 °C for 30 min) and acid (1, 2, and 3% H 2 SO 4 at 121 °C for 60 min) pretreated switchgrass was investigated. Briefly, the hydrolysis of cellobiose and Avicel with and without (control) lignin isolates was performed via CTec2 (5 and 10 FPU g -1 carbohydrate) to determine whether the presence of lignin and binding of cellulolytic enzymes to the isolated lignin can affect the sugar production using three carbohydrate-lignin loadings, namely, 0.5:0.25, 0.5:0.5, and 0.5:1.0% (wv -1 ). Based on SDS-PAGE results, β-glucosidase (BG) was significantly bound to all lignin isolates. Some enzymes in CTec2 presumed to be cellobiohydrolases, endo-1,4-β-glucanases, and xylanase, were also observed to partially bind to the lignin isolates. Up to 0.97 g glucose g -1 cellobiose was produced via hydrolysis (72 h and pH 4.8) with CTec2 (5 and 10 FPU g -1 carbohydrate). Similarly, up to 0.23 and 0.46 g glucose g -1 Avicel were produced via hydrolysis (72 h and pH 4.8) with 5 and 10 FPU g -1 carbohydrate, respectively. Results indicated that the addition of lignin isolates during cellobiose and Avicel hydrolysis did not significantly ( p  > 0.05) reduce glucose production regardless of type and amount of lignin isolate. Hence, even though BG was significantly bound to lignin isolates, it could maintain its functionality as a biological catalyst in this study.}, number={1}, journal={3 BIOTECH}, author={Jung, Woochul and Sharma-Shivappa, Ratna and Park, Sunkyu and Kolar, Praveen}, year={2020}, month={Jan} } @article{sagues_park_jameel_sanchez_2019, title={Enhanced carbon dioxide removal from coupled direct air capture-bioenergy systems}, volume={3}, ISSN={["2398-4902"]}, DOI={10.1039/c9se00384c}, abstractNote={Synergistic integration of BECCS and DAC systems decreases costs, increases carbon removal, and extends the impact of scarce biomass resources.}, number={11}, journal={SUSTAINABLE ENERGY & FUELS}, publisher={Royal Society of Chemistry (RSC)}, author={Sagues, William J. and Park, Sunkyu and Jameel, Hasan and Sanchez, Daniel L.}, year={2019}, month={Nov}, pages={3135–3146} } @article{corbett_knoll_venditti_jameel_park_2020, title={Fiber fractionation to understand the effect of mechanical refining on fiber structure and resulting enzymatic digestibility of biomass}, volume={117}, ISSN={0006-3592 1097-0290}, url={http://dx.doi.org/10.1002/bit.27258}, DOI={10.1002/bit.27258}, abstractNote={AbstractMechanical refining results in fiber deconstruction and modifications that enhance enzyme accessibility to carbohydrates. Further understanding of the morphological changes occurring to biomass during mechanical refining and the impacts of these changes on enzymatic digestibility is necessary to maximize yields and reduce energy consumption. Although the degree of fiber length reduction relative to fibrillation/delamination can be impacted by manipulating refining variables, mechanical refining of any type (PFI, disk, and valley beater) typically results in both phenomena. Separating the two is not straightforward. In this study, fiber fractionation based on particle size performed after mechanical refining of high‐lignin pulp was utilized to successfully elucidate the relative impact of fibrillation/delamination and fiber cutting phenomena during mechanical refining. Compositional analysis showed that fines contain significantly more lignin than larger size fractions. Enzymatic hydrolysis results indicated that within fractions of uniform fiber length, fibrillation/delamination due to mechanical refining increased enzymatic conversion by 20–30 percentage points. Changes in fiber length had little effect on digestibility for fibers longer than ~0.5 mm. However, the digestibility of the fines fractions was high for all levels of refining even with the high‐lignin content.}, number={4}, journal={Biotechnology and Bioengineering}, publisher={Wiley}, author={Corbett, Derek B. and Knoll, Charlie and Venditti, Richard and Jameel, Hasan and Park, Sunkyu}, year={2020}, month={Jan}, pages={924–932} } @article{corbett_hong_venditti_jameel_park_2019, title={Hydrophobic resin treatment of hydrothermal autohydrolysate for prebiotic applications}, volume={9}, ISSN={2046-2069}, url={http://dx.doi.org/10.1039/C9RA06018A}, DOI={10.1039/c9ra06018a}, abstractNote={∼30% of xylooligosaccharides (XOS) in autohydrolysate are likely bonded to lignin “tied,” contributing to loss during resin purification. Loss of “free” XOS depends on DP.}, number={55}, journal={RSC Advances}, publisher={Royal Society of Chemistry (RSC)}, author={Corbett, Derek B. and Hong, Changyoung and Venditti, Richard and Jameel, Hasan and Park, Sunkyu}, year={2019}, pages={31819–31827} } @article{park_yoo_lim_rojas_hubbe_park_2019, title={Impact of oxidative carbonization on structure development of loblolly pine-derived biochar investigated by nuclear magnetic resonance spectroscopy and X-ray photoelectron spectroscopy}, volume={96}, ISSN={["1879-0062"]}, DOI={10.1016/j.diamond.2019.05.001}, abstractNote={Biochar produced at an oxidative atmosphere shows distinct chemical properties compared to those of biochar produced at an inert atmosphere. However, there has been little investigation on the relationship between the oxidative atmosphere and the structure development of biochar, which can be useful information for the utilization of derived products. In this study, the effect of the oxygen atmosphere on the structure development of loblolly pine-derived biochar during thermal treatment was investigated. Quantitative analysis using solid-state direct polarization/magic angle spinning 13C nuclear magnetic resonance spectroscopy presented the existence of large fractions of aromatic and non-protonated carbons in the biochars treated at an oxidative atmosphere, implying highly condensed aromatic structures with large cluster sizes. Simultaneous thermogravimetic analyzer-differential scanning calorimetry was employed to demonstrate the difference in heat flow during the thermal treatment at two different atmospheres. Relatively large exothermic heat flow was observed when woody biomass was treated at 350 °C under an oxidative atmosphere which might be responsible for the difference in structural alteration. The series of observations suggested that compared to inert atmospheric conditions, admitting a limited amount of oxygen during thermal treatment of woody biomass could promote the evolution of condensed aromatic carbon structures.}, journal={DIAMOND AND RELATED MATERIALS}, author={Park, Junyeong and Yoo, Seunghyun and Lim, Kwang Hun and Rojas, Orlando J. and Hubbe, Martin A. and Park, Sunkyu}, year={2019}, month={Jun}, pages={140–147} } @article{abbas_peszlen_shi_kim_katahira_kafle_xiang_huang_min_mohamadamin_et al._2019, title={Involvement of CesA4, CesA7-A/B and CesA8-A/B in secondary wall formation in Populus trichocarpa wood}, volume={40}, ISSN={1758-4469}, url={http://dx.doi.org/10.1093/treephys/tpz020}, DOI={10.1093/treephys/tpz020}, abstractNote={Abstract Cellulose synthase A genes (CesAs) are responsible for cellulose biosynthesis in plant cell walls. In this study, functions of secondary wall cellulose synthases PtrCesA4, PtrCesA7-A/B and PtrCesA8-A/B were characterized during wood formation in Populus trichocarpa (Torr. & Gray). CesA RNAi knockdown transgenic plants exhibited stunted growth, narrow leaves, early necrosis, reduced stature, collapsed vessels, thinner fiber cell walls and extended fiber lumen diameters. In the RNAi knockdown transgenics, stems exhibited reduced mechanical strength, with reduced modulus of rupture (MOR) and modulus of elasticity (MOE). The reduced mechanical strength may be due to thinner fiber cell walls. Vessels in the xylem of the transgenics were collapsed, indicating that water transport in xylem may be affected and thus causing early necrosis in leaves. A dramatic decrease in cellulose content was observed in the RNAi knockdown transgenics. Compared with wildtype, the cellulose content was significantly decreased in the PtrCesA4, PtrCesA7 and PtrCesA8 RNAi knockdown transgenics. As a result, lignin and xylem contents were proportionally increased. The wood composition changes were confirmed by solid-state NMR, two-dimensional solution-state NMR and sum-frequency-generation vibration (SFG) analyses. Both solid-state nuclear magnetic resonance (NMR) and SFG analyses demonstrated that knockdown of PtrCesAs did not affect cellulose crystallinity index. Our results provided the evidence for the involvement of PtrCesA4, PtrCesA7-A/B and PtrCesA8-A/B in secondary cell wall formation in wood and demonstrated the pleiotropic effects of their perturbations on wood formation.}, number={1}, journal={Tree Physiology}, publisher={Oxford University Press (OUP)}, author={Abbas, Manzar and Peszlen, Ilona and Shi, Rui and Kim, Hoon and Katahira, Rui and Kafle, Kabindra and Xiang, Zhouyang and Huang, Xiong and Min, Douyong and Mohamadamin, Makarem and et al.}, editor={Plomion, ChristopheEditor}, year={2019}, month={Jun}, pages={73–89} } @article{lan_park_yao_2020, title={Key issue, challenges, and status quo of models for biofuel supply chain design}, ISBN={978-0-12-815582-0}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85083223493&partnerID=MN8TOARS}, DOI={10.1016/B978-0-12-815581-3.00010-5}, abstractNote={Biofuel supply chain (BSC) design is crucial for the sustainable production and distribution of biofuel. Many modeling techniques such as optimization and simulation have been employed to BSC at different regional and temporal scales. This chapter reviews the research efforts made in BSC since 2005 to highlight status quo, challenges, and issues related to BSC modeling and design. The basic concept and components of BSC are first introduced and followed by the review of different modeling techniques at various decision levels of BSC design. Challenges and issues identified throughout this review work are highlighted at the end and future research directions are discussed.}, journal={Biofuels for a More Sustainable Future: Life Cycle Sustainability Assessment and Multi-Criteria Decision Making}, author={Lan, Kai and Park, Sunkyu and Yao, Yuan}, year={2020}, pages={273–315} } @article{lan_ou_park_kelley_yao_2019, title={Life Cycle Analysis of Decentralized Preprocessing Systems for Fast Pyrolysis Biorefineries with Blended Feedstocks in the Southeastern United States}, volume={9}, ISSN={2194-4288 2194-4296}, url={http://dx.doi.org/10.1002/ente.201900850}, DOI={10.1002/ente.201900850}, abstractNote={Blending biomass feedstock is a promising approach to mitigate supply chain risks that are common challenges for large‐scale biomass utilization. Understanding the potential environmental benefits of biofuels produced from blended biomass and identifying driving parameters are critical for the supply chain design. Herein, a cradle‐to‐gate life cycle analysis model for fast pyrolysis biorefineries converting blended feedstocks (pine residues and switchgrass) with traditional centralized and alternative decentralized preprocessing sites, so‐called depots, is explained. Different scenarios are developed to investigate the impacts of parameters such as feedstock blending ratios, biorefinery and depot capacities, preprocessing technologies, and allocation methods. The life‐cycle energy consumption and global warming potential (GWP) of biofuel production with depots vary between 0.7–1.1 MJ MJ−1 and 43.2–76.6 g CO2 eq. MJ−1, respectively. The results are driven by biorefinery processes and depot preprocesses. A decentralized design reduces the energy consumption of the biorefinery but increases the overall life‐cycle energy and GWP. Such increases can be significantly mitigated by increasing switchgrass content as the energy consumption at the depot is driven largely by the higher moisture content of pine feedstocks. Allocation methods also have a large impact on the results but do not change the major trends and overall conclusions.}, number={11}, journal={Energy Technology}, publisher={Wiley}, author={Lan, Kai and Ou, Longwen and Park, Sunkyu and Kelley, Stephen S. and Yao, Yuan}, year={2019}, month={Sep}, pages={1900850} } @article{londhe_luo_park_kelley_fang_2019, title={Testing of anisole and methyl acetate as additives to diesel and biodiesel fuels in a compression ignition engine}, volume={246}, ISSN={["1873-7153"]}, url={https://doi.org/10.1016/j.fuel.2019.02.079}, DOI={10.1016/j.fuel.2019.02.079}, abstractNote={This paper investigates the effects of anisole and methyl acetate (as fuel additives) on the performance and emission characteristics of a compression-ignition (i.e., diesel) engine. Anisole and methyl acetate can be obtained from methylation of phenol and acetic acid, respectively. Phenol and acetic acid are compounds which are abundant in bio-oil derived from pyrolysis of wood and is thus renewable in nature. Using methyl acetate as a diesel fuel additive in compression-ignition engines has rarely been reported in the literature. The objective of the current work is to provide testing results of methyl acetate and perform comparisons with anisole as fuel additives for both diesel and biodiesel fuels. The effects of loads, additive type, and base fuels were tested. The tested loads include 0, 1.26, 2.52, and 3.78 bar brake mean effective pressure (BMEP) and the base fuels include No.2 diesel and biodiesel from waste cooking oil. The additive concentrations were kept at 10% by volume. Engine performance, exhaust emissions, and in-cylinder combustion were measured and analyzed. For diesel-anisole (DA) blends, it was seen that the blends were comparable to diesel in terms of performance but with slightly higher fuel consumption rates. HC and CO emissions reduced slightly, however, NOx and soot concentration increased. Diesel-methyl acetate (DM) blends were comparable to diesel in terms of performance with a slight increase in the fuel consumption rates. HC and CO emissions decreased with added methyl acetates. NOx and soot concentration increased. Both anisole and methyl acetate of 10% by volume in biodiesel were tested and it was observed that both blends were slightly better than pure biodiesel in terms of performance. HC and CO emissions reduced for both blends. NOx and soot concentration however increased as compared to pure biodiesel. From the experiments, it is believed that both anisole and methyl acetate can be used as suitable additives to diesel and biodiesel in terms of performance; however, the emissions of NOx and soot can pose a challenge.}, journal={FUEL}, publisher={Elsevier BV}, author={Londhe, Himanshu and Luo, Guanqun and Park, Sunkyu and Kelley, Stephen S. and Fang, Tiegang}, year={2019}, month={Jun}, pages={79–92} } @article{geng_narron_jiang_pawlak_chang_park_jameel_venditti_2019, title={The influence of lignin content and structure on hemicellulose alkaline extraction for non-wood and hardwood lignocellulosic biomass}, volume={26}, ISSN={0969-0239 1572-882X}, url={http://dx.doi.org/10.1007/s10570-019-02261-y}, DOI={10.1007/s10570-019-02261-y}, number={5}, journal={Cellulose}, publisher={Springer Science and Business Media LLC}, author={Geng, Wenhui and Narron, Robert and Jiang, Xiao and Pawlak, Joel J. and Chang, Hou-min and Park, Sunkyu and Jameel, Hasan and Venditti, Richard A.}, year={2019}, month={Jan}, pages={3219–3230} } @article{hong_corbett_venditti_jameel_park_2019, title={Xylooligosaccharides as prebiotics from biomass autohydrolyzate}, volume={111}, ISSN={0023-6438}, url={http://dx.doi.org/10.1016/j.lwt.2019.05.098}, DOI={10.1016/j.lwt.2019.05.098}, abstractNote={With an increased awareness of health and wellness, prebiotics have received a great amount of attention recently. In this study, autohydrolyzate from hot water treatment of Miscanthus lignocellulosic biomass was evaluated for its prebiotic effect by fermentation of Lactobacillus brevis strain. The cell growth on raw autohydrolyzate-supplemented media was comparable to the sample grown on glucose until an incubation time of 24 h then gradually declined. Autohydrolyzate contains various inhibitors (25.9% of total dissolved solids) and it was determined that dissolved lignin had a significant inhibitory effect to bacterial growth. When the autohydrolyzate was purified using a hydrophobic resin, purified autohydrolyzate exhibited high bacterial growth (cell density (OD 600) of 4.8) and high acid production (7.7 and 3.1 g/L of lactic and acetic acid, respectively), which was comparable with commercial xylooligosaccharides. In conclusion, mixed oligosaccharides in the autohydrolyzate from Miscanthus have considerable potential as a prebiotic and are comparable with commercial xylooligosaccharides derived products.}, journal={LWT}, publisher={Elsevier BV}, author={Hong, Changyoung and Corbett, Derek and Venditti, Richard and Jameel, Hasan and Park, Sunkyu}, year={2019}, month={Aug}, pages={703–710} } @article{jang_yoo_choi_park_kan_2018, title={Adsorption isotherm, kinetic modeling and mechanism of tetracycline on Pinus taeda-derived activated biochar}, volume={259}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2018.03.013}, abstractNote={The objective of this study was to evaluate the adsorption of tetracycline (TC) on the Pinus taeda-derived activated biochar (BC). After NaOH activation, the well-developed porous surface structure was observed with a significantly increase in surface area (959.9 m 2 /g). The kinetic and isotherm studies indicated that hydrogen bonding and π-π interaction on the heterogeneous surface would be the possible mechanisms, while intra-particle diffusion was considered as the major limitation for the adsorption of TC on the activated BC. The maximum adsorption capacity of the activated BC (274.8 mg TC/g BC) was higher than those of various activated BCs from the previous studies while it was similar to those of commercial activated carbons. It indicated that the activated BC had the high potential for TC removal in water.}, journal={BIORESOURCE TECHNOLOGY}, author={Jang, Hyun Min and Yoo, Seunghyun and Choi, Yong-Keun and Park, Sunkyu and Kan, Eunsung}, year={2018}, month={Jul}, pages={24–31} } @article{kim_lee_treasure_skotty_floyd_kelley_park_2019, title={Alkaline extraction and characterization of residual hemicellulose in dissolving pulp}, volume={26}, ISSN={["1572-882X"]}, DOI={10.1007/s10570-018-2137-0}, number={2}, journal={CELLULOSE}, author={Kim, Chae Hoon and Lee, Joo and Treasure, Trevor and Skotty, Jennifer and Floyd, Thomas and Kelley, Stephen S. and Park, Sunkyu}, year={2019}, month={Jan}, pages={1323–1333} } @article{edmunds_molina_andre_hamilton_park_fasina_adhikari_kelley_tumuluru_rials_et al._2018, title={Blended Feedstocks for Thermochemical Conversion: Biomass Characterization and Bio-Oil Production From Switchgrass-Pine Residues Blends}, volume={6}, ISSN={["2296-598X"]}, DOI={10.3389/fenrg.2018.00079}, abstractNote={An abundant, low-cost, and high-quality supply of lignocellulosic feedstock is necessary to realize the large-scale implementation of biomass conversion technologies capable of producing renewable fuels, chemicals, and products. Barriers to this goal include the variability in the chemical and physical properties of available biomass, and the seasonal and geographic availability of biomass. Blending several different types of biomass to produce consistent feedstocks offers a solution to these problems and allows for control over the specifications of the feedstocks. For thermochemical conversion processes, attributes of interest include carbon content, total ash, specific inorganics, density, particle size, and moisture content. In this work, a series of switchgrass and pine residues blends with varying physical and chemical properties were evaluated. Physical and chemical properties of the pure and blended materials were measured, including compositional analysis, elemental analysis, compressibility, flowability, density, and particle size distribution. To screen blends for thermochemical conversion behavior, the analytical technique, pyrolysis gas chromatography mass spectrometry (Py-GC/MS), was used to analyze the vapor-phase pyrolysis products of the various switchgrass/pine residues blends. The py-GC/MS findings were validated by investigating the bio-oils produced from the selected blends using a lab-scale fluidized-bed pyrolysis reactor system. Results indicate that the physical properties of blended materials are proportional to the blend ratio of pure feedstocks. In addition, pyrolysis of pine residues resulted in bio-oils with higher carbon content and lower oxygen content, while switchgrass derived pyrolysis products contained relatively greater amount of anhydrosugars and organic acids. The distribution of the pyrolysis vapors and isolated bio-oils appear to be a simple linear combination of the two feedstocks. The concentration of alkali and alkaline earth metals (Ca, K, Mg, and Na) in the blended feedstocks were confirmed to be a critical parameter due to their negative effects on the bio-oil yield. This work demonstrates that blending different sources of biomass can be an effective strategy to produce a consistent feedstock for thermochemical conversion.}, journal={FRONTIERS IN ENERGY RESEARCH}, author={Edmunds, Charles W. and Molina, Eliezer A. Reyes and Andre, Nicolas and Hamilton, Choo and Park, Sunkyu and Fasina, Oladiran and Adhikari, Sushil and Kelley, Stephen S. and Tumuluru, Jaya S. and Rials, Timothy G. and et al.}, year={2018}, month={Aug} } @article{kim_vinueza_kelley_park_2018, title={Correlation between solubility parameters and recovery of phenolic compounds from fast pyrolysis bio-oil by diesel extraction}, volume={1}, ISSN={2588-9133}, url={http://dx.doi.org/10.1016/J.CRCON.2018.08.004}, DOI={10.1016/J.CRCON.2018.08.004}, abstractNote={Fast pyrolysis bio-oils (fpBO) were extracted with two alternative commercial transportation fuels, hydrocarbon diesel and bio-diesel. The extraction of fpBO with commercial diesel fuel provided a yield of 4.3 wt%, but the yield increased significantly to 26.6 wt% when bio-diesel was the extractant. The molecular weight of fpBO before and after extraction were consistent with the loss of a more soluble, low molecular weight fraction from the crude fpBO. The relative energy difference (RED), based on the Hansen solubility parameter (HSP), is used to examine the extraction efficiency of specific compounds in the two different ‘solvents’. Differences in the RED values could be used to rationalize differences in the partitioning of common fpBO phenolics.}, number={3}, journal={Carbon Resources Conversion}, publisher={Elsevier BV}, author={Kim, Hoyong and Vinueza, Nelson R. and Kelley, Stephen S. and Park, Sunkyu}, year={2018}, month={Dec}, pages={238–244} } @article{corbett_venditti_jameel_park_2018, title={Effect of Mechanical Refining Energy on the Enzymatic Digestibility of Lignocellulosic Biomass}, volume={57}, ISSN={0888-5885 1520-5045}, url={http://dx.doi.org/10.1021/acs.iecr.8b02932}, DOI={10.1021/acs.iecr.8b02932}, abstractNote={Mechanical refining of lignocellulosic biomass has emerged as a promising technology for the improvement of enzymatic hydrolysis yields. Further research is necessary to understand the effects of mechanical refining at different conditions to allow for further optimization of the process. In this research, the impact of refining intensity (specific edge load; kWh/m) is investigated by the use of multiple refining passes to reach equivalent total specific refining energy (SRE) using a 12-in. disk refiner. In addition, the effect of adjusting gap-width vs adjusting consistency to increase refining energy is explored. Results show that enzymatic carbohydrate conversion is a function of SRE, independent of refining intensity. At lower enzyme loadings, gap-width adjustments were observed to be most effective at improving enzymatic digestibility. At higher enzyme loadings carbohydrate conversions leveled-off slightly as SRE increased, implying that there may be an economically optimum degree of refining.}, number={43}, journal={Industrial & Engineering Chemistry Research}, publisher={American Chemical Society (ACS)}, author={Corbett, Derek B. and Venditti, Richard and Jameel, Hasan and Park, Sunkyu}, year={2018}, month={Oct}, pages={14648–14655} } @article{jang_yoo_park_kan_2019, title={Engineered biochar from pine wood: Characterization and potential application for removal of sulfamethoxazole in water}, volume={24}, ISSN={["2005-968X"]}, DOI={10.4491/eer.2018.358}, abstractNote={The adsorption of sulfamethoxazole (SMX) onto a NaOH-activated pine wood-derived biochar was investigated via batch experiments and models. Surprisingly, the maximum adsorption capacity of activated biochar for SMX (397.29 mg/g) was superior than those of pristine biochars from various feedstock, but comparable to those of commercially available activated carbons. Elovich kinetic and Freundlich isotherm models revealed the best fitted ones for the adsorption of SMX onto the activated biochar indicating chemisorptive interaction occurred on surface of the activated biochar. In addition, the intraparticle diffusion limitation was thought to be the major barrier for the adsorption of SMX on the activated biochar. The main mechanisms for the activated biochar would include hydrophobic, π-π interactions and hydrogen bonding. This was consistent with the changes in physicochemical properties of the activated biochar (e.g., increase in sp and surface area, but decrease in the ratios of O/C and H/C).}, number={4}, journal={ENVIRONMENTAL ENGINEERING RESEARCH}, author={Jang, Hyun Min and Yoo, Seunghyun and Park, Sunkyu and Kan, Eunsung}, year={2019}, month={Dec}, pages={608–617} } @article{liu_chang_jameel_park_2018, title={Furfural production from biomass pretreatment hydrolysate using vapor-releasing reactor system}, volume={252}, ISSN={0960-8524}, url={http://dx.doi.org/10.1016/j.biortech.2018.01.006}, DOI={10.1016/j.biortech.2018.01.006}, abstractNote={Biomass hydrolysate from autohydrolysis pretreatment was used for furfural production considering it is in rich of xylose, xylo-oligomers, and other decomposition products from hemicellulose structure. By using the vapor-releasing reactor system, furfural was protected from degradation by separating it from the reaction media. The maximum furfural yield of 73% was achieved at 200 °C for biomass hydrolysate without the use of the catalyst. This is because the presence of organic acids such as acetic acid in hydrolysate functioned as a catalyst. According to the results in this study, biomass hydrolysate with a vapor-releasing system proves to be efficient for furfural production. The biorefinery process which allows the separation of xylose-rich autohydrolysate from other parts from biomass feedstock also improves the overall application of the biomass.}, journal={Bioresource Technology}, publisher={Elsevier BV}, author={Liu, Lu and Chang, Hou-min and Jameel, Hasan and Park, Sunkyu}, year={2018}, month={Mar}, pages={165–171} } @article{yoo_chung_kelley_park_2018, title={Graphitization Behavior of Loblolly Pine Wood Investigated by in Situ High Temperature X-ray Diffraction}, volume={6}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.8b01446}, abstractNote={Graphitization is a complex process involving chemical and morphological changes, although the detailed mechanism for different starting materials is not well understood. In this work, in situ high temperature X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were used to examine the phase transition occurring between 1000 and 1500 °C in loblolly pine wood-derived carbon materials. Electron energy loss spectroscopy (EELS) was also used to study these wood-derived carbon materials. XRD data showed the disappearance of a disordered carbon phase between 1300 and 1400 °C, followed by the formation of a crystalline graphitic phase between 1400 and 1500 °C. Lattice parameters and the crystal structure of the loblolly pine wood-derived graphite were systematically calculated from the empirical data. The presence of a large endothermic peak at 1500 °C in the DSC thermogram supported this observation. Selected area electron diffraction patterns showed the growth of graphitic crystallites after he...}, number={7}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Yoo, Seunghyun and Chung, Ching-Chang and Kelley, Stephen S. and Park, Sunkyu}, year={2018}, month={Jul}, pages={9113–9119} } @article{ou_kim_kelley_park_2018, title={Impacts of feedstock properties on the process economics of fast-pyrolysis biorefineries}, volume={12}, ISSN={["1932-1031"]}, DOI={10.1002/bbb.1860}, abstractNote={AbstractFeedstock properties are an important factor affecting the process yields and economics of fast‐pyrolysis biorefineries. This study develops a fast‐pyrolysis process model sensitive to feedstock properties based on experimental results. Sixty‐four simulations are run to evaluate the impacts of carbon, ash, and moisture content in biomass feedstocks on process yields and energy consumptions. An economic analysis is conducted for each run to quantify process economics under different feedstock properties. With biomass feedstocks of 48% carbon and 15% moisture, minimum fuel selling price (MFSP) increases from $0.97/L to $1.06/L when ash content increases from 1% to 7%, due to reduced hydrocarbon yields. With biomass feedstocks of 48% carbon and 3% ash content, MFSP increases from $1.03/L to $1.08/L when feedstock moisture increases from 15% to 45% as a consequence of increased energy demand for feedstock drying. The impact of feedstock ash content decreases gradually as ash content increases. Feedstock carbon content has less significant impacts on process economics in this study. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd}, number={3}, journal={BIOFUELS BIOPRODUCTS & BIOREFINING-BIOFPR}, author={Ou, Longwen and Kim, Hoyong and Kelley, Stephen and Park, Sunkyu}, year={2018}, pages={442–452} } @article{boes_narron_park_vinueza_2018, title={Mass Spectrometry Exposes Undocumented Lignin-Carbohydrate Complexes in Biorefinery Pretreatment Stream}, volume={6}, ISSN={2168-0485 2168-0485}, url={http://dx.doi.org/10.1021/ACSSUSCHEMENG.8B01986}, DOI={10.1021/ACSSUSCHEMENG.8B01986}, abstractNote={The presence and effects of lignin–carbohydrate complexes (LCCs) in biorefinery processes are largely unknown. Recently identified in a significant hydrothermal pretreatment process stream (autohydrolyzate), these molecules likely influence not only downstream processing but also product purity and performance. However, without an understanding of their structures, it is impossible to analyze and cope with their effects. To identify and elucidate LCCs in autohydrolyzate, a new method employed chloride doping and tandem mass spectrometry. The results showed complexes ranging in mass from 326–714 Da with evidence of xylose and glucose units. Further analysis revealed lignin-like levels of unsaturation, considering the number of carbons present. These results suggest that, although the complexes contain one or two carbohydrate units, their primary structures are closer to lignin compounds. This method provides a glimpse into the structures of LCCs in a biorefinery process stream, laying the foundation for ea...}, number={8}, journal={ACS Sustainable Chemistry & Engineering}, publisher={American Chemical Society (ACS)}, author={Boes, Kelsey S. and Narron, Robert H. and Park, Sunkyu and Vinueza, Nelson R.}, year={2018}, month={Jul}, pages={10654–10659} } @article{barton_carrier_segura_fierro_park_lamb_escalona_peretti_2018, title={Ni/HZSM-5 catalyst preparation by deposition-precipitation. Part 2. Catalytic hydrodeoxygenation reactions of lignin model compounds in organic and aqueous systems}, volume={562}, ISSN={0926-860X}, url={http://dx.doi.org/10.1016/J.APCATA.2018.06.012}, DOI={10.1016/J.APCATA.2018.06.012}, abstractNote={Nickel metal supported on HZSM-5 (zeolite) is a promising catalyst for lignin depolymerization. In this work, the ability of catalysts prepared via deposition-precipitation (DP) to perform hydrodeoxygenation (HDO) on two lignin model compounds in organic and aqueous solvents was evaluated; guaiacol in dodecane and 2-phenoxy-1-phenylethanol (PPE) in aqueous solutions. All Ni/HZSM-5 catalysts were capable of guaiacol HDO into cyclohexane at 523 K. The role of the HZSM-5 acid sites was confirmed by comparison with Ni/SiO2 (inert support) which exhibited incomplete deoxygenation of guaiacol due to the inability to perform the cyclohexanol dehydration step. The catalyst prepared with 15 wt% Ni, a DP time of 16 h, and a calcination temperature of 673 K (Ni(15)/HZSM-5 DP16_Cal673), performed the guaiacol conversion with the greatest selectivity towards HDO products, with an intrinsic rate ratio (HDO rate to conversion rate) of 0.31, and 90% selectivity to cyclohexane. Catalytic activity and selectivity of Ni/HZSM-5 (15 wt%) in aqueous environments (water and 0.1 M NaOH solution) was confirmed using PPE reactions at 523 K. After 30 min reaction time in water, Ni/HZSM-5 exhibited ∼100% conversion of PPE, and good yield of the desired products; ethylbenzene and phenol (∼35% and 23% of initial carbon, respectively). Ni/HZSM-5 in NaOH solution resulted in significantly higher ring saturation compared to the Ni/HZSM-5 in water or the NaOH solution control.}, journal={Applied Catalysis A: General}, publisher={Elsevier BV}, author={Barton, R.R. and Carrier, M. and Segura, C. and Fierro, J.L.G. and Park, S. and Lamb, H.H. and Escalona, N. and Peretti, S.W.}, year={2018}, month={Jul}, pages={294–309} } @article{yoo_kelley_tilotta_park_2018, title={Structural Characterization of Loblolly Pine Derived Biochar by X-ray Diffraction and Electron Energy Loss Spectroscopy}, volume={6}, ISSN={2168-0485 2168-0485}, url={http://dx.doi.org/10.1021/ACSSUSCHEMENG.7B04119}, DOI={10.1021/acssuschemeng.7b04119}, abstractNote={Biochar from lignocellulosic biomass is emerging as a sustainable material with versatile applications, but its detailed properties are poorly understood because of its structural complexity. We propose a biochar structural development model based on experimental results including composition analysis, surface area and pore analysis, X-ray diffraction analysis, electron microscopy imaging, and electron energy loss spectroscopy. Loblolly pine derived biochars were produced at different carbonization temperatures between 300 to 1000 °C. Fixed carbon, sp2 content, and number of graphene layers increased with increased carbonization temperature. Alternating average C–C bond length, interlayer spacing distance, and layer coherence length were observed. Bulk plasmon excitation energy was correlated to the average C–C bond length, and it serves as a good indicator of the carbon structure development when compared to the perfect graphitic carbon structure. On the basis of the experimental results, four different ...}, number={2}, journal={ACS Sustainable Chemistry & Engineering}, publisher={American Chemical Society (ACS)}, author={Yoo, Seunghyun and Kelley, Stephen S. and Tilotta, David C. and Park, Sunkyu}, year={2018}, month={Jan}, pages={2621–2629} } @misc{nelson_park_hubbe_2018, title={Thermal Depolymerization of Biomass with Emphasis on Gasifier Design and Best Method for Catalytic Hot Gas Conditioning}, volume={13}, ISSN={["1930-2126"]}, DOI={10.15376/biores.13.2.nelson}, abstractNote={This paper reviews ways that biomass can be converted by thermal depolymerization to make synthetic gas, i.e. syngas. Biomass, being carbon neutral, is considered as a form of solar energy stored during the growing season by photosynthesis. An effective biomass is one with low moisture and ash content, high lignin content, high calorific value, and small particle size. Woody biomass with low ash content (<1%), nut shells with high lignin content (30 to 40%), and municipal solid waste with synthetic polymers are effective at creating value-added synthetic gases. An allothermal downdraft gasifier produces a low tar syngas (99.9% tar conversion) at 850 oC and provides a simple and low-cost process. Integrated gasification combined cycle (IGCC) improves thermodynamic efficiency. To avoid thermal loss, a hot gas filtration system uses trona sorption material for sulfur and halogen compounds. Secondary systems can use multiple cyclones followed by reactors employing calcined dolomite, olivine, and others for adsorption or reaction with residual sulfur, ammonia, metals, and halogens. Reforming of residual tar to syngas can take place within chambers with ceramic tubes doped with nano-nickel particles. Syngas can then be used in boilers, gas turbines for production of electricity or production of chemicals by Fischer-Tropsch conversion.}, number={2}, journal={BIORESOURCES}, author={Nelson, Larry and Park, Sunkyu and Hubbe, Martin A.}, year={2018} } @article{assis_huang_driemeier_donohoe_kim_kim_gonzalez_jameel_park_2018, title={Toward an understanding of the increase in enzymatic hydrolysis by mechanical refining}, volume={11}, ISSN={["1754-6834"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85055631061&partnerID=MN8TOARS}, DOI={10.1186/s13068-018-1289-3}, abstractNote={Mechanical refining is a low-capital and well-established technology used in pulp and paper industry to improve fiber bonding for product strength. Refining can also be applied in a biorefinery context to overcome the recalcitrance of pretreated biomass by opening up the biomass structure and modifying substrate properties (e.g., morphology, particle size, porosity, crystallinity), which increases enzyme accessibility to substrate and improves carbohydrate conversion. Although several characterization methods have been used to identify the changes in substrate properties, there is no systematic approach to evaluate the extent of fiber cell wall disruption and what physical properties can explain the improvement in enzymatic digestibility when pretreated lignocellulosic biomass is mechanically refined. This is because the fiber cell wall is complex across multiple scales, including the molecular scale, nano- and meso-scale (microfibril), and microscale (tissue level). A combination of advanced characterization tools is used in this study to better understand the effect of mechanical refining on the meso-scale microfibril assembly and the relationship between those meso-scale modifications and enzymatic hydrolysis.Enzymatic conversion of autohydrolysis sugarcane bagasse was improved from 69.6 to 77.2% (11% relative increase) after applying mechanical refining and an increase in enzymatic digestibility is observed with an increase in refining intensity. Based on a combination of advanced characterizations employed in this study, it was found that the refining action caused fiber size reduction, internal delamination, and increase in pores and swellability.A higher level of delamination and higher increase in porosity, analyzed by TEM and DSC, were clearly demonstrated, which explain the faster digestibility rate during the first 72 h of enzymatic hydrolysis for disc-refined samples when compared to the PFI-refined samples. In addition, an increased inter-fibrillar distance between cellulose microfibrils at the nano-meso-scale was also revealed by SFG analysis, while no evidence was found for a change in crystalline structure by XRD and solid-state NMR analysis.}, number={1}, journal={BIOTECHNOLOGY FOR BIOFUELS}, author={Assis, Tiago and Huang, Shixin and Driemeier, Carlos Eduardo and Donohoe, Bryon S. and Kim, Chaehoon and Kim, Seong H. and Gonzalez, Ronalds and Jameel, Hasan and Park, Sunkyu}, year={2018}, month={Oct} } @article{koo_park_gonzalez_jameel_park_2019, title={Two-stage autohydrolysis and mechanical treatment to maximize sugar recovery from sweet sorghum bagasse}, volume={276}, ISSN={["1873-2976"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85059462040&partnerID=MN8TOARS}, DOI={10.1016/j.biortech.2018.12.112}, abstractNote={Modified autohydrolysis combined with mechanical refining has been suggested to recover free sugars from sweet sorghum bagasse and facilitates enzyme access to cellulose in bagasse for enhancing its conversion to fermentable sugars. The amount of total available sugars in sweet sorghum bagasse was found to be 76.1% and this value was used to evaluate the efficiency of the process suggested. Total sugar recovery was achieved up to 68.1% through the single-stage autohydrolysis at 170 °C for 60 min, followed by mechanical refining and enzymatic hydrolysis; however, the sugar recovery through partial degradation of free sugars induced by high-temperature autohydrolysis was lower than expected. A modified two-stage autohydrolysis was suggested to prevent sugar degradation and the total sugar recovery using this process reached 83.9% of total available sugars in sweet sorghum bagasse.}, journal={BIORESOURCE TECHNOLOGY}, author={Koo, Bonwook and Park, Junyeong and Gonzalez, Ronalds and Jameel, Hasan and Park, Sunkyu}, year={2019}, month={Mar}, pages={140–145} } @article{ou_luo_ray_li_hu_kelley_park_2018, title={Understanding the Impacts of Biomass Blending on the Uncertainty of Hydrolyzed Sugar Yield from a Stochastic Perspective}, volume={6}, ISSN={2168-0485 2168-0485}, url={http://dx.doi.org/10.1021/ACSSUSCHEMENG.8B02150}, DOI={10.1021/ACSSUSCHEMENG.8B02150}, abstractNote={Feedstock price and availability are key challenges for biorefinery development. Biomass blending has been suggested as a route to overcome these limitations. However, the impacts of feedstock blending on the uncertainty in hydrolyzed sugar yields remain unclear. This study quantifies the uncertainties in the sugar yields from hydrolysis of the blends of corn stover, switchgrass, and grass clippings by considering both feedstock compositional variation and model uncertainty. The results indicate that feedstock blending reduces the uncertainties in sugar yields and delivers feedstock of more uniform quality. A 60/35/5 blend of corn stover, switchgrass, and grass clippings on average achieves a glucose yield of 32.6 g/100 g of biomass, which is comparable to those of corn stover (33.3 g/100 g) and switchgrass (32.9 g/100 g), but drastically higher than that of grass clippings (21.7 g/100 g). This same blend also achieves the lowest variance in glucose yield (2.9 g/100 g) compared to corn stover (3.1 g/100 g...}, number={8}, journal={ACS Sustainable Chemistry & Engineering}, publisher={American Chemical Society (ACS)}, author={Ou, Longwen and Luo, Guanqun and Ray, Allison and Li, Chenlin and Hu, Hongqiang and Kelley, Stephen and Park, Sunkyu}, year={2018}, month={Jun}, pages={10851–10860} } @article{liu_chang_jameel_park_park_2017, title={Catalytic Conversion of Biomass Hydrolysate into 5-Hydroxymethylfurfural}, volume={56}, ISSN={0888-5885 1520-5045}, url={http://dx.doi.org/10.1021/acs.iecr.7b03635}, DOI={10.1021/acs.iecr.7b03635}, abstractNote={Biomass hydrolysate, rich in glucose, was used to produce an important platform chemical, 5-hydroxymethylfurfural (HMF). By separating the solid biomass from solution after autohydrolysis, most of the inhibitors were removed from hydrolysate. Biphasic system, which prevents the HMF degradation, was optimized with HCl and AlCl3 catalysts. The yield of HMF conversion using biomass hydrolyzate under the optimized reaction conditions is comparable to the yield using pure glucose as a feedstock. This lab-generated HMF was purified via activated charcoal and oxidized to high value-added chemical, 2,5-furandicarboxylic acid (FDCA). The final FDCA yield of 65% was achieved. The results suggest that, with the separation of nonsugar components such as dissolved lignin and sugar degradation products, biomass hydrolysate is a promising source for HMF and FDCA production.}, number={49}, journal={Industrial & Engineering Chemistry Research}, publisher={American Chemical Society (ACS)}, author={Liu, Lu and Chang, Hou-min and Jameel, Hasan and Park, Ji-Yeon and Park, Sunkyu}, year={2017}, month={Nov}, pages={14447–14453} } @article{ren_meng_chang_kelley_jameel_park_2017, title={Effect of blending ratio of loblolly pine wood and bark on the properties of pyrolysis bio-oils}, volume={167}, ISSN={["1873-7188"]}, DOI={10.1016/j.fuproc.2017.06.025}, abstractNote={Bark, which is available in abundance, has recently become a topic of interest when considering alternative materials for the production of pyrolysis bio-oil. Previous studies have revealed that the pyrolysis behavior of bark differs remarkably from that of wood in that bark typically generates a phase-separated bio-oil. In this study, blends of loblolly pine wood and bark were pyrolyzed to investigate the effect of blending ratio on the yield and properties of derived bio-oils. Trends of lower decomposition rate, decreased organic yield, and increased bio-char yield were observed as bark percentage in the feedstock increased, while the amount of levoglucosan in bio-oil increased. Pyrolysis reactivity, which includes yield and physical properties of the bio-oil, was found to have a linear relationship with the blending ratio of pine bark. It was found that blending up to 50% bark in the feedstock still produced a homogeneous bio-oil.}, journal={FUEL PROCESSING TECHNOLOGY}, author={Ren, Xueyong and Meng, Jiajia and Chang, Jianmin and Kelley, Stephen S. and Jameel, Hasan and Park, Sunkyu}, year={2017}, month={Dec}, pages={43–49} } @article{he_yoo_meng_yildiz_bradford_park_gao_2017, title={Engineering biorefinery residues from loblolly pine for supercapacitor applications}, volume={120}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2017.05.056}, abstractNote={Recycling agricultural waste biomass into high-value-added products is of great importance to offset the cost of biofuel production. Here, we make biochar-based activated carbons (BACs) from loblolly pine chips via different carbonization recipes and chemical activations. BACs were then assembled into electrochemical double-layer capacitors (EDLCs) as electrode materials. Surprisingly, pyrolysis at lower temperatures (300 °C and 350 °C) rendered better electrochemical performance of BACs than those done at higher temperatures (500 °C and 700 °C). This is mainly due to the large surface area and high pore volume generated at the lower temperatures. Among all the pyrolysis recipes, flash pyrolysis at 300 °C produced the BAC with the highest specific capacitance (74 F g−1 at 20 mV s−1), exceeding the specific capacitance of commercial activated carbon (NORIT®) by 45%. This report demonstrates the great potential of our refinery recipe to engineer BACs from the sustainable, affordable, and abundant natural wastes for energy-storage applications, which opens the door for a group of biorefinery residues for value-added applications.}, journal={CARBON}, author={He, Nanfei and Yoo, Seunghyun and Meng, Jiajia and Yildiz, Ozkan and Bradford, Philip D. and Park, Sunkyu and Gao, Wei}, year={2017}, month={Aug}, pages={304–312} } @article{narron_han_park_chang_jameel_2017, title={Lignocentric analysis of a carbohydrate-producing lignocellulosic biorefinery process}, volume={241}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2017.05.207}, abstractNote={A biologically-based lignocellulosic biorefinery process for obtaining carbohydrates from raw biomass was investigated across six diverse biomasses (three hardwoods & three nonwoods) for the purpose of decoding lignin's influence on sugar production. Acknowledging that lignin could positively alter the economics of an entire process if valorized appropriately, we sought to correlate the chemical properties of lignin within the process to the traditional metrics associated with carbohydrate production-cellulolytic digestibility and total sugar recovery. Based on raw carbohydrate, enzymatic recovery ranged from 40 to 64% w/w and total recovery ranged from 70 to 87% w/w. Using nitrobenzene oxidation to quantify non-condensed lignin structures, it was found that raw hardwoods bearing increasing non-condensed S/V ratios (2.5-5.1) render increasing total carbohydrate recovery from hardwood biomasses. This finding indicates that the chemical structure of hardwood lignin influences the investigated biorefinery process' ability to generate carbohydrates from a given raw hardwood feedstock.}, journal={BIORESOURCE TECHNOLOGY}, author={Narron, Robert H. and Han, Qiang and Park, Sunkyu and Chang, Hou-min and Jameel, Hasan}, year={2017}, month={Oct}, pages={857–867} } @article{jones_venditti_park_jameel_2017, title={Optimization of Pilot Scale Mechanical Disk Refining for Improvements in Enzymatic Digestibility of Pretreated Hardwood Lignocellulosics}, volume={12}, ISSN={1930-2126}, url={http://dx.doi.org/10.15376/biores.12.3.4567-4593}, DOI={10.15376/biores.12.3.4567-4593}, abstractNote={Mechanical refining has potential application for overcoming lignocellulosic biomass recalcitrance to enzyme hydrolysis and improving biomass digestibility. This study highlighted the ability for a pilot scale disc refiner to improve the total carbohydrate conversion to sugars from 39% (unrefined hardwood sodium carbonate biomass) to 90% (0.13 mm gap, 20% consistency, ambient temperature) by optimizing the refining variables. The different biomass properties that changed with refining indicated the expected increase in sugar conversion. Controlling the refining parameters to narrower gaps and higher consistencies increased the resulting refined biomass hydrolysis. Positive correlations that increases in net specific energy (NSE) input and refining intensity (SEL) improved the enzymatic hydrolysis. In some severe cases, over-refining occurred when smaller gaps, higher consistencies, and more energy input reached a point of diminished return. The energy input in these scenarios, however, was much greater than realistically feasible for industrial application. Although well-established in the pulp and paper industry, gaps in understanding the fundamentals of refining remain. The observations and results herein provide the justification and opportunity for further mechanical refining optimization to maximize and adapt the mechanical refining technology for maximum efficiency within the process of biochemical conversion to sugar.}, number={3}, journal={BioResources}, publisher={BioResources}, author={Jones, Brandon W. and Venditti, Richard and Park, Sunkyu and Jameel, Hasan}, year={2017}, month={May}, pages={4567–4593} } @article{ansanay_kolar_sharma-shivappa_cheng_park_arellano_2017, title={Pre-treatment of biomasses using magnetised sulfonic acid catalysts}, volume={48}, number={2}, journal={Journal of Agricultural Engineering}, author={Ansanay, Y. and Kolar, P. and Sharma-Shivappa, R. and Cheng, J. and Park, S. and Arellano, C.}, year={2017}, pages={117–122} } @article{narron_chang_jameel_park_2017, title={Soluble Lignin Recovered from Biorefinery Pretreatment Hydrolyzate Characterized by Lignin-Carbohydrate Complexes}, volume={5}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.7b02716}, abstractNote={The lignin rendered soluble by lignocellulosic biorefinery pretreatment remains insufficiently understood along the lines of molecular properties and chemical composition. To procure a representative soluble lignin preparation, an aromatic-selective adsorptive resin was utilized. Approximately 90% of soluble lignin could be recovered from autohydrolysis pretreatment hydrolyzate (autohydrolyzate) produced from a hardwood and a nonwood biomass. Adsorbate compositional characterization revealed a befuddling magnitude of carbohydrate in selectively isolated lignin adsorbates. Quantitative structural analysis of the lignin by NMR suggested lignin–carbohydrate complexes (LCCs) as the cause behind the pronounced carbohydrate contents. Analyzed spectra revealed both hardwood and nonwood soluble lignin features of ∼10 total LCC per 100 aromatic rings, with each lignin bearing unique LCC profiles. In addition, native structures remained in large quantities. The improved understanding of hydrolyzate-soluble lignin g...}, number={11}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Narron, Robert H. and Chang, Hou-min and Jameel, Hasan and Park, Sunkyu}, year={2017}, month={Nov}, pages={10763–10771} } @misc{narron_kim_chang_jameel_park_2016, title={Biomass pretreatments capable of enabling lignin valorization in a biorefinery process}, volume={38}, ISSN={["1879-0429"]}, DOI={10.1016/j.copbio.2015.12.018}, abstractNote={Recent techno-economic studies of proposed lignocellulosic biorefineries have concluded that creating value from lignin will assist realization of biomass utilization into valuable fuels, chemicals, and materials due to co-valorization and the new revenues beyond carbohydrates. The pretreatment step within a biorefinery process is essential for recovering carbohydrates, but different techniques and intensities have a variety of effects on lignin. Acidic and alkaline pretreatments have been shown to produce diverse lignins based on delignification chemistry. The valorization potential of pretreated lignin is affected by its chemical structure, which is known to degrade, including inter-lignin condensation under high-severity pretreatment. Co-valorization of lignin and carbohydrates will require dampening of pretreatment intensities to avoid such effects, in spite of tradeoffs in carbohydrate production.}, journal={CURRENT OPINION IN BIOTECHNOLOGY}, author={Narron, Robert H. and Kim, Hoyong and Chang, Hou-min and Jameel, Hasan and Park, Sunkyu}, year={2016}, month={Apr}, pages={39–46} } @article{boes_narron_chen_park_vinueza_2017, title={Characterization of biofuel refinery byproduct via selective electrospray ionization tandem mass spectrometry}, volume={188}, ISSN={["1873-7153"]}, DOI={10.1016/j.fuel.2016.10.016}, abstractNote={To achieve economic viability, biorefineries need to increase efficiency through characterization of byproducts for the purpose of valorization. One such byproduct is the liquid stream produced after autohydrolysis pretreatment, autohydrolyzate liquor, which contains valuable organic derivatives of hemicellulose and lignin from biomass. To characterize the autohydrolysis liquor, we employed a novel method for such liquor analysis that uses electrospray ionization and ion dopants in combination with tandem mass spectrometry using a quadrupole–time-of-flight mass spectrometer. Electrospray expands current analysis of such liquors through softer ionization. Ion dopants provide for differentiation of the complex mixture components without requiring derivatization or preliminary separation. The dopants—ammonium chloride and sodium hydroxide—primarily target and enhance ionization of hemicellulosic or lignin derivative species, respectively, based on the species’ differing functionalities. Valuable structural information can be gleaned from these enhanced species by ion isolation and collision-activated dissociation (CAD), which reveals the presence of hemicellulosic or lignin derivative functionalities. These ionization techniques coupled with CAD enabled us to not only confirm the presence of low molecular weight ions, such as vanillin, as previously seen with gas chromatography-mass spectrometry but also expand the characterization to high molecular weight species. This expanded knowledge of the composition of autohydrolyzate liquor opens up the potential to develop lucrative co-products from this stream in a commercial biorefinery.}, journal={FUEL}, author={Boes, Kelsey S. and Narron, Robert H. and Chen, Yufei and Park, Sunkyu and Vinueza, Nelson R.}, year={2017}, month={Jan}, pages={190–196} } @article{park_wang_lee_jameel_jin_park_2016, title={Effect of the Two-Stage Autohydrolysis of Hardwood on the Enzymatic Saccharification and Subsequent Fermentation with an Efficient Xylose-Utilizing Saccharomyces cerevisiae}, volume={11}, ISSN={["1930-2126"]}, DOI={10.15376/biores.11.4.9584-9595}, abstractNote={To effectively utilize sugars during the fermentation process, it is important to develop a process that can minimize the generation of inhibiting compounds such as furans and acids, and a robust micro-organism that can co-ferment both glucose and xylose into products. In this study, the feasibility of efficient ethanol production was investigated using a combination of two approaches: two-stage autohydrolysis of biomass and fermentation using an engineered Saccharomyces cerevisiae to produce ethanol. When the hardwood chips were autohydrolyzed at 140 °C, followed by the second treatment at 180 °C, a higher yield of sugar conversion and fewer inhibitory effects on subsequent fermentation were achieved compared with the results from single-stage autohydrolysis. A higher overall yield of ethanol resulted by using an engineered yeast strain, SR8. This observation suggests the possibility of the feasible combination of two-stage autohydrolysis and the recombinant yeast.}, number={4}, journal={BIORESOURCES}, author={Park, Junyeong and Wang, Ziyu and Lee, Won-Heong and Jameel, Hasan and Jin, Yong-Su and Park, Sunkyu}, year={2016}, month={Nov}, pages={9584–9595} } @article{lee_park_2016, title={Removal of furan and phenolic compounds from simulated biomass hydrolysates by batch adsorption and continuous fixed-bed column adsorption methods}, volume={216}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2016.06.007}, abstractNote={It has been proposed to remove all potential inhibitors and sulfuric acid in biomass hydrolysates generated from dilute-acid pretreatment of biomass, based on three steps of sugar purification process. This study focused on its first step in which furan and phenolic compounds were selectively removed from the simulated hydrolysates using activated charcoal. Batch adsorption experiments demonstrated that the affinity of activated charcoal for each component was highest in the order of vanillic acid, 4-hydroxybenzoic acid, furfural, acetic acid, sulfuric acid, and xylose. The affinity of activated charcoal for furan and phenolic compounds proved to be significantly higher than that of the other three components. Four separation strategies were conducted with a combination of batch adsorption and continuous fixed-bed column adsorption methods. It was observed that xylose loss was negligible with near complete removal of furan and phenolic compounds, when at least one fixed-bed column adsorption was implemented in the strategy.}, journal={BIORESOURCE TECHNOLOGY}, author={Lee, Sang Cheol and Park, Sunkyu}, year={2016}, month={Sep}, pages={661–668} } @inbook{lee_dazen_kafle_moore_johnson_park_kim_2015, place={Cham, Switzerland}, series={Advances in Polymer Science}, title={Correlations of Apparent Cellulose Crystallinity Determined by XRD, NMR, IR, Raman, and SFG Methods}, ISBN={9783319260136 9783319260150}, ISSN={0065-3195 1436-5030}, url={http://dx.doi.org/10.1007/12_2015_320}, DOI={10.1007/12_2015_320}, abstractNote={Although the cellulose crystallinity index (CI) is used widely, its limitations have not been adequately described. In this study, the CI values of a set of reference samples were determined from X-ray diffraction (XRD), nuclear magnetic resonance (NMR), and infrared (IR), Raman, and vibrational sum frequency generation (SFG) spectroscopies. The intensities of certain crystalline peaks in IR, Raman, and SFG spectra positively correlated with the amount of crystalline cellulose in the sample, but the correlation with XRD was nonlinear as a result of fundamental differences in detection sensitivity to crystalline cellulose and improper baseline corrections for amorphous contributions. It is demonstrated that the intensity and shape of the XRD signal is affected by both the amount of crystalline cellulose and crystal size, which makes XRD analysis complicated. It is clear that the methods investigated show the same qualitative trends for samples, but the absolute CI values differ depending on the determination method. This clearly indicates that the CI, as estimated by different methods, is not an absolute value and that for a given set of samples the CI values can be compared only as a qualitative measure.}, booktitle={Cellulose Chemistry and Properties: Fibers, Nanocelluloses and Advanced Materials}, publisher={Springer International Publishing}, author={Lee, Christopher and Dazen, Kevin and Kafle, Kabindra and Moore, Andrew and Johnson, David K. and Park, Sunkyu and Kim, Seong H.}, editor={Rojas, O.Editor}, year={2015}, pages={115–131}, collection={Advances in Polymer Science} } @article{park_shin_yoo_zoppe_park_2015, title={Delignification of Lignocellulosic Biomass and Its Effect on Subsequent Enzymatic Hydrolysis}, volume={10}, ISSN={["1930-2126"]}, DOI={10.15376/biores.10.2.2732-2743}, abstractNote={The effect of delignification on the enzymatic hydrolysis of biomass was investigated to determine how different delignification processes affect enzymatic hydrolysis conversion yields. Oxygen, hydrogen peroxide, and sodium chlorite treatments were performed, and the structural and chemical changes in the biomass were evaluated. Sodium chlorite delignification proved the most effective process to remove lignin in hardwood samples, followed by oxygen delignification. Hydrogen peroxide delignification was not as effective as the other two methods. As for the enzymatic conversion of carbohydrates after delignification processes on hardwood, oxygen and sodium chlorite treatments substantially improved conversion yields as the number of successive treatments was increased, compared to untreated hardwood samples. Changes in α-cellulose after delignification were less substantial than those of hardwood samples, and corresponding conversion yields were also lower. Delignification-induced structural changes in treated substrates might be responsible for the changes in carbohydrate conversion yield observed following subsequent enzymatic hydrolysis.}, number={2}, journal={BIORESOURCES}, author={Park, Junyeong and Shin, Heenae and Yoo, Seunghyun and Zoppe, Justin O. and Park, Sunkyu}, year={2015}, pages={2732–2743} } @article{kafle_lee_shin_zoppe_johnson_kim_park_2015, title={Effects of Delignification on Crystalline Cellulose in Lignocellulose Biomass Characterized by Vibrational Sum Frequency Generation Spectroscopy and X-ray Diffraction}, volume={8}, ISSN={["1939-1242"]}, DOI={10.1007/s12155-015-9627-9}, number={4}, journal={BIOENERGY RESEARCH}, author={Kafle, Kabindra and Lee, Christopher M. and Shin, Heenae and Zoppe, Justin and Johnson, David K. and Kim, Seong H. and Park, Sunkyu}, year={2015}, month={Dec}, pages={1750–1758} } @article{moore_park_segura_carrier_2015, title={Fast pyrolysis of lignin-coated radiata pine}, volume={115}, ISSN={["1873-250X"]}, DOI={10.1016/j.jaap.2015.07.017}, abstractNote={A new coating preparative method of the Pinus radiata feedstock was used to process a mixture of Acetocell lignin and sawdust prepared at different mass ratios of lignin to sawdust, 1:18 (LI20) and 1:7 (LI40) to overcome feeding issues into a fluidized bed pyrolysis reactor. The coated materials were structurally characterized by using spectrometric and microscopic techniques, which respectively confirmed the presence of saturated aliphatic and oxygenated side chains in the isolated lignin and the formation of a boundary layer around the woody biomass particles. The fast pyrolysis of the coated materials at 540 °C led to the decrease of both total liquid and organic yields and to the substantial increase of reactive water yield. Like yields, the addition of the technical lignin affected the product composition of fast pyrolysis bio-oil. These changes were both related to the oxygenated aliphatic nature of the lignin side-chains and to the thickness of the coating layer. This new preparation technique of the feedstock overcomes the technical barriers associated with the feeding of thermoset polymers into a bubbling fluidized bed reactor, without modifying its initial design; and enhanced the production of the phenolic rich fraction by controlling the thickness of the coating.}, journal={JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS}, author={Moore, Andrew and Park, Sunkyu and Segura, Cristina and Carrier, Marion}, year={2015}, month={Sep}, pages={203–213} } @article{chen_wang_ciesielski_trass_park_tao_tucker_2016, title={Improving Sugar Yields and Reducing Enzyme Loadings in the Deacetylation and Mechanical Refining (DMR) Process through Multistage Disk and Szego Refining and Corresponding Techno-Economic Analysis}, volume={4}, ISSN={["2168-0485"]}, DOI={10.1021/acssuschemeng.5b01242}, abstractNote={Deacetylation and mechanical refining (DMR) has the potential to be a highly efficient biochemical conversion process for converting biomass to low toxicity, high concentration sugar streams. To increase the cost-effectiveness of the DMR process, improvements in enzymatic sugar yields are needed, in addition to reducing the refining energy consumed, and decreasing the enzyme usage. In this study, a second refining step utilizing a Szego mill was introduced, resulting in significant improvements in sugar yields in enzymatic hydrolysis at equivalent or lower refining energy inputs. The multistage DMR process increased the monomeric glucose and xylose yields to approximately 90% and 84%, respectively, with an energy consumption of 200 kWh/ODMT. SEM imaging revealed that Szego milling caused significant surface disruption and severe maceration and delamination of the biomass structure. Our results show that the DMR process is a very promising process for the biorefinery industry in terms of economic feasibility.}, number={1}, journal={ACS SUSTAINABLE CHEMISTRY & ENGINEERING}, author={Chen, Xiaowen and Wang, Wei and Ciesielski, Peter and Trass, Olev and Park, Sunkyu and Tao, Ling and Tucker, Melvin P.}, year={2016}, month={Jan}, pages={324–333} } @article{kafle_shin_lee_park_kim_2015, title={Progressive structural changes of Avicel, bleached softwood, and bacterial cellulose during enzymatic hydrolysis}, volume={5}, ISSN={["2045-2322"]}, DOI={10.1038/srep15102}, abstractNote={AbstractA comprehensive picture of structural changes of cellulosic biomass during enzymatic hydrolysis is essential for a better understanding of enzymatic actions and development of more efficient enzymes. In this study, a suite of analytical techniques including sum frequency generation (SFG) spectroscopy, infrared (IR) spectroscopy, x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) were employed for lignin-free model biomass samples—Avicel, bleached softwood and bacterial cellulose—to find correlations between the decrease in hydrolysis rate over time and the structural or chemical changes of biomass during the hydrolysis reaction. The results showed that the decrease in hydrolysis rate over time appears to correlate with the irreversible deposition of non-cellulosic species (either reaction side products or denatured enzymes, or both) on the cellulosic substrate surface. The crystallinity, degree of polymerization and meso-scale packing of cellulose do not seem to positively correlate with the decrease in hydrolysis rate observed for all three substrates tested in this study. It was also found that the cellulose Iα component of the bacterial cellulose is preferentially hydrolyzed by the enzyme than the cellulose Iβ component.}, journal={SCIENTIFIC REPORTS}, author={Kafle, Kabindra and Shin, Heenae and Lee, Christopher M. and Park, Sunkyu and Kim, Seong H.}, year={2015}, month={Oct} } @article{geng_jin_jameel_park_2015, title={Strategies to achieve high-solids enzymatic hydrolysis of dilute-acid pretreated corn stover}, volume={187}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2015.03.067}, abstractNote={Three strategies were presented to achieve high solids loading while maximizing carbohydrate conversion, which are fed-batch, splitting/thickening, and clarifier processes. Enzymatic hydrolysis was performed at water insoluble solids (WIS) of 15% using washed dilute-acid pretreated corn stover. The carbohydrate concentration increased from 31.8 to 99.3g/L when the insoluble solids content increased from 5% to 15% WIS, while the final carbohydrate conversion was decreased from 78.4% to 73.2%. For the fed-batch process, a carbohydrate conversion efficiency of 76.8% was achieved when solid was split into 60:20:20 ratio, with all enzymes added first. For the splitting/thickening process, a carbohydrate conversion of 76.5% was realized when the filtrate was recycled to simulate a steady-state process. Lastly, the clarifier process was evaluated and the highest carbohydrate conversion of 81.4% was achieved. All of these results suggests the possibility of enzymatic hydrolysis at high solids to make the overall conversion cost-competitive.}, journal={BIORESOURCE TECHNOLOGY}, author={Geng, Wenhui and Jin, Yongcan and Jameel, Hasan and Park, Sunkyu}, year={2015}, month={Jul}, pages={43–48} } @article{meng_moore_tilotta_kelley_adhikari_parkt_2015, title={Thermal and Storage Stability of Bio-Oil from Pyrolysis of Torrefied Wood}, volume={29}, ISSN={["1520-5029"]}, DOI={10.1021/acs.energyfuels.5b00929}, abstractNote={The objective of this paper is to investigate the biomass torrefaction effect on bio-oil stability by comparing the physicochemical and compositional properties of aged bio-oils. Two aging methods, accelerated aging (held at 80 °C for 24 h) and long-term natural aging (12-month storage at 25 °C), were employed to produce aged bio-oils for such comparison. The results indicate that bio-oils made from heat-treated wood had similar aging behavior in terms of increase of water content, acid content, molecular weight, and viscosity. The increase rate, however, was found to be different and dependent on the aging method. The accelerated method found parallel water and total acidity number (TAN) increments between raw and torrefaction bio-oils, while the natural aging method found torrefaction bio-oils, especially those made from heavily treated wood, had much slower water and acid accumulation than that of raw bio-oil. As a negative effect, both methods identified the viscosity of torrefaction bio-oils increase...}, number={8}, journal={ENERGY & FUELS}, author={Meng, Jiajia and Moore, Andrew and Tilotta, David C. and Kelley, Stephen S. and Adhikari, Sushil and Parkt, Sunkyu}, year={2015}, month={Aug}, pages={5117–5126} } @article{park_jones_koo_chen_tucker_yu_pschorn_venditti_park_2016, title={Use of mechanical refining to improve the production of low-cost sugars from lignocellulosic biomass}, volume={199}, ISSN={0960-8524}, url={http://dx.doi.org/10.1016/J.BIORTECH.2015.08.059}, DOI={10.1016/J.BIORTECH.2015.08.059}, abstractNote={Mechanical refining is widely used in the pulp and paper industry to enhance the end-use properties of products by creating external fibrillation and internal delamination. This technology can be directly applied to biochemical conversion processes. By implementing mechanical refining technology, biomass recalcitrance to enzyme hydrolysis can be overcome and carbohydrate conversion can be enhanced with commercially attractive levels of enzymes. In addition, chemical and thermal pretreatment severity can be reduced to achieve the same level of carbohydrate conversion, which reduces pretreatment cost and results in lower concentrations of inhibitors. Refining is versatile and a commercially proven technology that can be operated at process flows of ∼ 1500 dry tons per day of biomass. This paper reviews the utilization of mechanical refining in the pulp and paper industry and summarizes the recent development in applications for biochemical conversion, which potentially make an overall biorefinery process more economically viable.}, journal={Bioresource Technology}, publisher={Elsevier BV}, author={Park, Junyeong and Jones, Brandon and Koo, Bonwook and Chen, Xiaowen and Tucker, Melvin and Yu, Ju-Hyun and Pschorn, Thomas and Venditti, Richard and Park, Sunkyu}, year={2016}, month={Jan}, pages={59–67} } @article{chen_shekiro_pschorn_sabourin_tao_elander_park_jennings_nelson_trass_et al._2014, title={A highly efficient dilute alkali deacetylation and mechanical (disc) refining process for the conversion of renewable biomass to lower cost sugars}, volume={7}, ISSN={["1754-6834"]}, DOI={10.1186/1754-6834-7-98}, abstractNote={The deconstruction of renewable biomass feedstocks into soluble sugars at low cost is a critical component of the biochemical conversion of biomass to fuels and chemicals. Providing low cost high concentration sugar syrups with low levels of chemicals and toxic inhibitors, at high process yields is essential for biochemical platform processes using pretreatment and enzymatic hydrolysis. In this work, we utilize a process consisting of deacetylation, followed by mechanical refining in a disc refiner (DDR) for the conversion of renewable biomass to low cost sugars at high yields and at high concentrations without a conventional chemical pretreatment step. The new process features a low temperature dilute alkaline deacetylation step followed by disc refining under modest levels of energy consumption. The proposed process was demonstrated using a commercial scale Andritz double disc refiner. Disc refined and deacetylated corn stover result in monomeric glucose yields of 78 to 84% and monomeric xylose yields of 71 to 77% after enzymatic hydrolysis at process-relevant solids and enzyme loadings. The glucose and xylose yields of the disc refined substrates in enzymatic hydrolysis are enhanced by 13% and 19%, respectively. Fermentation of the DDR substrates at 20% total solids with Z.mobilis utilized almost all sugars in 20hrs indicating the sugar hydrolyzate produced from the DDR process is highly fermentable due to low levels of chemical contaminants. The ethanol titer and ethanol process yield are approximately 70 g/L and 90% respectively. The proposed new process has been demonstrated using pilot scale deacetylation and disc refiners. The deacetylated and disc refined corn stover was rapidly deconstructed to monomeric sugars at 20% wt solids with enzymatic hydrolysis. High process sugar conversions were achieved, with high concentrations of monomeric sugars that exceeded 150 g/L. The sugar syrups produced were found to have low concentrations of known major fermentation inhibitors: acetic acid, furfural and HMF. The low levels of these fermentation inhibitors lead to high fermentation yields. The results suggest that this process is a very promising development for the nascent cellulosic biofuels industry.}, journal={BIOTECHNOLOGY FOR BIOFUELS}, author={Chen, Xiaowen and Shekiro, Joseph and Pschorn, Thomas and Sabourin, Marc and Tao, Ling and Elander, Rick and Park, Sunkyu and Jennings, Ed and Nelson, Robert and Trass, Olev and et al.}, year={2014}, month={Jun} } @article{han_jin_jameel_chang_phillips_park_2015, title={Autohydrolysis Pretreatment of Waste Wheat Straw for Cellulosic Ethanol Production in a Co-located Straw Pulp Mill}, volume={175}, ISSN={["1559-0291"]}, DOI={10.1007/s12010-014-1349-5}, abstractNote={Waste wheat straw (WWS) is the waste product from feedstock preparation process in a straw pulp mill. It has a significant annual production rate and no commercial value has been explored on this material. In this study, waste wheat straw was pretreated using an autohydrolysis process followed by mechanical refining, and the pretreated materials were further enzymatically hydrolyzed to evaluate the total sugar recovery for bioethanol production. Results show that autohydrolysis at 170 °C for 40 min followed by 6000 revolution PFI refining provided the best result in this study, where a total sugar recovery (total sugars in autohydrolysis filtrate and enzymatic hydrolyzate over total carbohydrates on raw WWS) of 70 % at 4 filter paper unit per oven dry gram (FPU/OD g) substrate enzyme charge could be obtained. The economic evaluation of this biorefinery process indicates that cellulosic ethanol production from autohydrolysis of WWS is a very profitable business, with 28.4 % of internal rate of return can be achieved based on current ethanol wholesale price in China.}, number={2}, journal={APPLIED BIOCHEMISTRY AND BIOTECHNOLOGY}, author={Han, Qiang and Jin, Yanbin and Jameel, Hasan and Chang, Hou-min and Phillips, Richard and Park, Sunkyu}, year={2015}, month={Jan}, pages={1193–1210} } @article{srinivasan_adhikari_chattanathan_tu_park_2014, title={Catalytic Pyrolysis of Raw and Thermally Treated Cellulose Using Different Acidic Zeolites}, volume={7}, ISSN={["1939-1242"]}, DOI={10.1007/s12155-014-9426-8}, number={3}, journal={BIOENERGY RESEARCH}, author={Srinivasan, Vaishnavi and Adhikari, Sushil and Chattanathan, Shyamsundar Ayalur and Tu, Maobing and Park, Sunkyu}, year={2014}, month={Sep}, pages={867–875} } @article{jones_venditti_park_jameel_2014, title={Comparison of lab, pilot, and industrial scale low consistency mechanical refining for improvements in enzymatic digestibility of pretreated hardwood}, volume={167}, ISSN={0960-8524}, url={http://dx.doi.org/10.1016/j.biortech.2014.06.026}, DOI={10.1016/j.biortech.2014.06.026}, abstractNote={Mechanical refining has been shown to improve biomass enzymatic digestibility. In this study industrial high-yield sodium carbonate hardwood pulp was subjected to lab, pilot and industrial refining to determine if the mechanical refining improves the enzymatic hydrolysis sugar conversion efficiency differently at different refining scales. Lab, pilot and industrial refining increased the biomass digestibility for lignocellulosic biomass relative to the unrefined material. The sugar conversion was increased from 36% to 65% at 5 FPU/g of biomass with industrial refining at 67.0 kWh/t, which was more energy efficient than lab and pilot scale refining. There is a maximum in the sugar conversion with respect to the amount of refining energy. Water retention value is a good predictor of improvements in sugar conversion for a given fiber source and composition. Improvements in biomass digestibility with refining due to lab, pilot plant and industrial refining were similar with respect to water retention value.}, journal={Bioresource Technology}, publisher={Elsevier BV}, author={Jones, Brandon W. and Venditti, Richard and Park, Sunkyu and Jameel, Hasan}, year={2014}, month={Sep}, pages={514–520} } @article{chen_venditti_gonzalez_phillips_jameel_park_2014, title={Economic evaluation of the conversion of industrial paper sludge to ethanol}, volume={44}, ISSN={0140-9883}, url={http://dx.doi.org/10.1016/j.eneco.2014.04.018}, DOI={10.1016/j.eneco.2014.04.018}, abstractNote={The conversion of industrial paper sludge to ethanol was simulated using engineering process simulation software loaded with laboratory generated conversion data and financially analyzed. In one scenario, sludge is fractionated to remove ash, generating a higher concentration carbohydrate stream for separate hydrolysis and fermentation (SHF). In a second scenario, non-fractionated sludge is processed with only pH adjustment. Four primary sludges from mills producing either virgin or recycled paper were analyzed and the experimental conversion results used to inform the simulations. Financial analysis was conducted assuming ethanol wholesale price of US$ 0.608 per liter. The most profitable case was fractionated virgin sludge (from a virgin paper mill) to ethanol (F-VK1) with a net present value (NPV) of US$ 11.4 million, internal rate of return (IRR) of 28%, payback period of 4.4 years and minimum ethanol revenue (MER) of US$ 0.32 per liter. Risk analysis showed that the F-VK1 case obtained a near 100% probability of business success with both central and bearish (pessimistic) assumptions.}, journal={Energy Economics}, publisher={Elsevier BV}, author={Chen, Hui and Venditti, Richard and Gonzalez, Ronalds and Phillips, Richard and Jameel, Hasan and Park, Sunkyu}, year={2014}, month={Jul}, pages={281–290} } @article{yu_gwak_treasure_jameel_chang_park_2014, title={Effect of Lignin Chemistry on the Enzymatic Hydrolysis of Woody Biomass}, volume={7}, ISSN={["1864-564X"]}, DOI={10.1002/cssc.201400042}, abstractNote={AbstractThe impact of lignin‐derived inhibition on enzymatic hydrolysis is investigated by using lignins isolated from untreated woods and pretreated wood pulps. A new method, biomass reconstruction, for which isolated lignins are precipitated onto bleached pulps to mimic lignocellulosic biomass, is introduced, for the first time, to decouple the lignin distribution issue from lignin chemistry. Isolated lignins are physically mixed and reconstructed with bleached pulps. Lignins obtained from pretreated woods adsorb two to six times more cellulase than lignins obtained from untreated woods. The higher adsorption of enzymes on lignin correlates with decreased carbohydrate conversion in enzymatic hydrolysis. In addition, the reconstructed softwood substrate has a lower carbohydrate conversion than the reconstructed hardwood substrate. The degree of condensation of lignin increases significantly after pretreatment, especially with softwood lignins. In this study, the degree of condensation of lignin (0.02 to 0.64) and total OH groups in lignin (1.7 to 1.1) have a critical impact on cellulase adsorption (9 to 70 %) and enzymatic hydrolysis (83.2 to 58.2 %); this may provide insights into the more recalcitrant nature of softwood substrates.}, number={7}, journal={CHEMSUSCHEM}, author={Yu, Zhiying and Gwak, Ki-Seob and Treasure, Trevor and Jameel, Hasan and Chang, Hou-min and Park, Sunkyu}, year={2014}, month={Jul}, pages={1942–1950} } @article{wang_chen_donohoe_ciesielski_katahira_kuhn_kafle_lee_park_kim_et al._2014, title={Effect of mechanical disruption on the effectiveness of three reactors used for dilute acid pretreatment of corn stover Part 1: chemical and physical substrate analysis}, volume={7}, ISSN={["1754-6834"]}, DOI={10.1186/1754-6834-7-57}, abstractNote={There is considerable interest in the conversion of lignocellulosic biomass to liquid fuels to provide substitutes for fossil fuels. Pretreatments, conducted to reduce biomass recalcitrance, usually remove at least some of the hemicellulose and/or lignin in cell walls. The hypothesis that led to this research was that reactor type could have a profound effect on the properties of pretreated materials and impact subsequent cellulose hydrolysis. Corn stover was dilute-acid pretreated using commercially relevant reactor types (ZipperClave® (ZC), Steam Gun (SG) and Horizontal Screw (HS)) under the same nominal conditions. Samples produced in the SG and HS achieved much higher cellulose digestibilities (88% and 95%, respectively), compared to the ZC sample (68%). Characterization, by chemical, physical, spectroscopic and electron microscopy methods, was used to gain an understanding of the effects causing the digestibility differences. Chemical differences were small; however, particle size differences appeared significant. Sum-frequency generation vibrational spectra indicated larger inter-fibrillar spacing or randomization of cellulose microfibrils in the HS sample. Simons' staining indicated increased cellulose accessibility for the SG and HS samples. Electron microscopy showed that the SG and HS samples were more porous and fibrillated because of mechanical grinding and explosive depressurization occurring with these two reactors. These structural changes most likely permitted increased cellulose accessibility to enzymes, enhancing saccharification. Dilute-acid pretreatment of corn stover using three different reactors under the same nominal conditions gave samples with very different digestibilities, although chemical differences in the pretreated substrates were small. The results of the physical and chemical analyses of the samples indicate that the explosive depressurization and mechanical grinding with these reactors increased enzyme accessibility. Pretreatment reactors using physical force to disrupt cell walls increase the effectiveness of the pretreatment process.}, journal={BIOTECHNOLOGY FOR BIOFUELS}, author={Wang, Wei and Chen, Xiaowen and Donohoe, Bryon S. and Ciesielski, Peter N. and Katahira, Rui and Kuhn, Erik M. and Kafle, Kabindra and Lee, Christopher M. and Park, Sunkyu and Kim, Seong H. and et al.}, year={2014}, month={Apr} } @article{park_lee_kafle_park_cosgrove_kim_2014, title={Effects of Plant Cell Wall Matrix Polysaccharides on Bacterial Cellulose Structure Studied with Vibrational Sum Frequency Generation Spectroscopy and X-ray Diffraction}, volume={15}, ISSN={["1526-4602"]}, DOI={10.1021/bm500567v}, abstractNote={The crystallinity, allomorph content, and mesoscale ordering of cellulose produced by Gluconacetobacter xylinus cultured with different plant cell wall matrix polysaccharides were studied with vibrational sum frequency generation (SFG) spectroscopy and X-ray diffraction (XRD). Crystallinity and ordering were assessed as the intensity of SFG signals in the CH/CH2 stretch vibration region (and confirmed by XRD), while Iα content was assessed by the relative intensity of the OH stretch vibration at 3240 cm(-1). A key finding is that the presence of xyloglucan in the culture medium greatly reduced Iα allomorph content but with a relatively small effect on cellulose crystallinity, whereas xylan resulted in a larger decrease in crystallinity with a relatively small decrease in the Iα fraction. Arabinoxylan and various pectins had much weaker effects on cellulose structure as assessed by SFG and XRD. Homogalacturonan with calcium ion reduced the SFG signal, evidently by changing the ordering of cellulose microfibrils. We propose that the distinct effects of matrix polysaccharides on cellulose crystal structure result, at least in part, from selective interactions of the backbone and side chains of matrix polysaccharides with cellulose chains during the formation of the microfibril.}, number={7}, journal={BIOMACROMOLECULES}, author={Park, Yong Bum and Lee, Christopher M. and Kafle, Kabindra and Park, Sunkyu and Cosgrove, Daniel J. and Kim, Seong H.}, year={2014}, month={Jul}, pages={2718–2724} } @article{meng_smirnova_song_moore_ren_kelley_park_tilotta_2014, title={Identification of free radicals in pyrolysis oil and their impact on bio-oil stability}, volume={4}, ISSN={["2046-2069"]}, DOI={10.1039/c4ra02007c}, abstractNote={The existence of radicals in pyrolysis oil generated from loblolly pine in three different reactor systems was verified with electron paramagnetic resonance (EPR) spectroscopy.}, number={56}, journal={RSC ADVANCES}, author={Meng, Jiajia and Smirnova, Tatyana I. and Song, Xiao and Moore, Andrew and Ren, Xueyong and Kelley, Stephen and Park, Sunkyu and Tilotta, David}, year={2014}, pages={29840–29846} } @article{treasure_gonzalez_jameel_phillips_park_kelley_2014, title={Integrated conversion, financial, and risk modeling of cellulosic ethanol from woody and non-woody biomass via dilute acid pre-treatment}, volume={8}, ISSN={1932-104X}, url={http://dx.doi.org/10.1002/bbb.1494}, DOI={10.1002/bbb.1494}, abstractNote={AbstractDilute sulfuric acid pre‐treatment followed by enzymatic hydrolysis and fermentation is a technology widely studied as a potential pathway for conversion of lignocellulosic biomass to ethanol. Six feedstocks were evaluated in process and financial simulations. The woody feedstocks include natural hardwood, Eucalyptus, and loblolly pine while the non‐woody feedstocks include corn stover, switchgrass, and sweet sorghum. Based on experimental and literature data, ethanol yields for the non‐woody biomasses range from 315 to 328 liters per bone dry metric ton (L/BDt). Sweet sorghum that is pressed and washed to remove soluble sugars prior to dilute acid processing can have an ethanol yield of approximately 470 L/BDt. Natural hardwood and Eucalyptus produce ethanol yields of 336 and 309 L/BDt, respectively. When processing 700 000 bone dry metric tons per year, the non‐woody biomasses have lower minimum ethanol revenues to achieve a 12% internal rate of return (MER@12%) than the woody biomasses. The non‐wood MER@12% ranged from $0.70 to $080/liter while the MER@12% for natural hardwood and Eucalyptus was $0.84–$0.85/liter. The impact of feedstock composition variability on the net present value at 12% (NPV@12%) discount was estimated for corn stover, switchgrass, and loblolly pine. One standard deviation in the sample carbohydrate content for corn stover, switchgrass, and loblolly pine will impact the NPV@12% by approximately $40 M, $72 M, and $24 M, respectively. If recent historical cost and revenue variability continues for the life of the project the most attractive feedstock is squeezed sweet sorghum where the probability of achieving at least a 12% internal rate of return is 64%.}, number={6}, journal={Biofuels, Bioproducts and Biorefining}, publisher={Wiley}, author={Treasure, Trevor and Gonzalez, Ronalds and Jameel, Hasan and Phillips, Richard B. and Park, Sunkyu and Kelley, Steve}, year={2014}, month={May}, pages={755–769} } @article{meng_moore_tilotta_kelley_park_2014, title={Toward Understanding of Bio-Oil Aging: Accelerated Aging of Bio-Oil Fractions}, volume={2}, ISSN={2168-0485 2168-0485}, url={http://dx.doi.org/10.1021/sc500223e}, DOI={10.1021/sc500223e}, abstractNote={Pyrolysis bio-oil from biomass is a promising intermediate for producing transportation fuels and platform chemicals. However, its instability, often called aging, has been identified as a critical hurdle that prevents bio-oil from being commercialized. The objective of this research is to explore the bio-oil aging mechanism by an accelerated aging test of fractionated bio-oil produced from loblolly pine. When water soluble (WS), ether insoluble (EIS), and pyrolytic lignin (PL) fractions were aged separately, the increased molecular weight (Mw) was observed with increasing aging temperature and the presence of acids. WS and EIS fractions had high Mw brown solids formed after aging. Adjusting the pH of WS and EIS fractions from 2.5 to 7.0 significantly reduced the tendency of a Mw increase. Similar Mw rise was also observed on a PL fraction with an elevated temperature and acid addition. Formaldehyde was found to react with the PL fraction in the presence of any acid catalysts tested, i.e., 8-fold Mw incre...}, number={8}, journal={ACS Sustainable Chemistry & Engineering}, publisher={American Chemical Society (ACS)}, author={Meng, Jiajia and Moore, Andrew and Tilotta, David and Kelley, Stephen and Park, Sunkyu}, year={2014}, month={Jul}, pages={2011–2018} } @article{kafle_shi_lee_mittal_park_sun_park_chiang_kim_2014, title={Vibrational sum-frequency-generation (SFG) spectroscopy study of the structural assembly of cellulose microfibrils in reaction woods}, volume={21}, ISSN={["1572-882X"]}, DOI={10.1007/s10570-014-0322-3}, number={4}, journal={CELLULOSE}, author={Kafle, Kabindra and Shi, Rui and Lee, Christopher M. and Mittal, Ashutosh and Park, Yong Bum and Sun, Ying-Hsuan and Park, Sunkyu and Chiang, Vincent and Kim, Seong H.}, year={2014}, month={Aug}, pages={2219–2231} } @article{park_hung_gan_rojas_lim_park_2013, title={Activated carbon from biochar: Influence of its physicochemical properties on the sorption characteristics of phenanthrene}, volume={149}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2013.09.085}, abstractNote={The relationship between physicochemical properties of biochar-based activated carbons and its adsorption was investigated using an aromatic model compound, phenanthrene. Solid-state 13C NMR analysis indicated more condensed aromatic structures when pyrolysis temperature increased or after activation process induced. The increasing aromaticity and non-protonated carbon fraction of the activated biochar treated at 300 °C amounted to 14.7% and 24.0%, respectively, compared to 7.4% and 4.4% for biochar treated at 700 °C. The surface area and pore volume were reduced with the increase in pyrolysis temperature, but increased after activation. Surface characteristics correlated with the initial sorption rate and equilibrium concentration of phenanthrene, but not with the aromaticity. Solid-state 2H NMR for phenanthrene-d10 saturated activated biochars, however, showed substantial difference in molecular mobility, which might be due to the high aromaticity of the activated biochars. Overall, these results provide an opportunity to manipulate the characteristics of biomass-based adsorbents based on the application needs.}, journal={BIORESOURCE TECHNOLOGY}, author={Park, Junyeong and Hung, Ivan and Gan, Zhehong and Rojas, Orlando J. and Lim, Kwang Hun and Park, Sunkyu}, year={2013}, month={Dec}, pages={383–389} } @article{jung_park_lim_park_heo_her_oh_yun_yoon_2013, title={Adsorption of selected endocrine disrupting compounds and pharmaceuticals on activated biochars}, volume={263}, ISSN={["1873-3336"]}, DOI={10.1016/j.jhazmat.2013.10.033}, abstractNote={Chemically activated biochar produced under oxygenated (O-biochar) and oxygen-free (N-biochar) conditions were characterized and the adsorption of endocrine disrupting compounds (EDCs): bisphenol A (BPA), atrazine (ATR), 17 α-ethinylestradiol (EE2), and pharmaceutical active compounds (PhACs); sulfamethoxazole (SMX), carbamazepine (CBM), diclofenac (DCF), ibuprofen (IBP) on both biochars and commercialized powdered activated carbon (PAC) were investigated. Characteristic analysis of adsorbents by solid-state nuclear magnetic resonance (NMR) was conducted to determine better understanding about the EDCs/PhACs adsorption. N-biochar consisted of higher polarity moieties with more alkyl (0-45 ppm), methoxyl (45-63 ppm), O-alkyl (63-108 ppm), and carboxyl carbon (165-187 ppm) content than other adsorbents, while aromaticity of O-biochar was higher than that of N-biochar. O-biochar was composed mostly of aromatic moieties, with low H/C and O/C ratios compared to the highly polarized N-biochar that contained diverse polar functional groups. The higher surface area and pore volume of N-biochar resulted in higher adsorption capacity toward EDCs/PhACs along with atomic-level molecular structural property than O-biochar and PAC. N-biochar had a highest adsorption capacity of all chemicals, suggesting that N-biochar derived from loblolly pine chip is a promising sorbent for agricultural and environmental applications. The adsorption of pH-sensitive dissociable SMX, DCF, IBP, and BPA varied and the order of adsorption capacity was correlated with the hydrophobicity (Kow) of adsorbates throughout the all adsorbents, whereas adsorption of non-ionizable CBM, ATR, and EE2 in varied pH allowed adsorbents to interact with hydrophobic property of adsorbates steadily throughout the study.}, journal={JOURNAL OF HAZARDOUS MATERIALS}, author={Jung, Chanil and Park, Junyeong and Lim, Kwang Hun and Park, Sunkyu and Heo, Jiyong and Her, Namguk and Oh, Jeill and Yun, Soyoung and Yoon, Yeomin}, year={2013}, month={Dec}, pages={702–710} } @article{lee_mittal_barnette_kafle_park_shin_johnson_park_kim_2013, title={Cellulose polymorphism study with sum-frequency-generation (SFG) vibration spectroscopy: identification of exocyclic CH2OH conformation and chain orientation}, volume={20}, ISSN={0969-0239 1572-882X}, url={http://dx.doi.org/10.1007/s10570-013-9917-3}, DOI={10.1007/s10570-013-9917-3}, number={3}, journal={Cellulose}, publisher={Springer Science and Business Media LLC}, author={Lee, Christopher M. and Mittal, Ashutosh and Barnette, Anna L. and Kafle, Kabindra and Park, Yong Bum and Shin, Heenae and Johnson, David K. and Park, Sunkyu and Kim, Seong H.}, year={2013}, month={Apr}, pages={991–1000} } @article{chen_kuhn_wang_park_flanegan_trass_tenlep_tao_tucker_2013, title={Comparison of different mechanical refining technologies on the enzymatic digestibility of low severity acid pretreated corn stover}, volume={147}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2013.07.109}, abstractNote={The effect of mechanical refining on the enzymatic digestibility of pretreated corn stover (PCS) was investigated. Low severity, dilute sulfuric acid PCS was subjected to mechanical refining using a bench-scale food processor blender, a PFI mill, a 12-inch laboratory disk refiner, and a 25 mm co-rotating twin-screw extruder. Glucose yields from enzymatic hydrolysis were improved by 10-15% after blending and disk refining, while PFI refining and twin-screw extrusion showed a glucose yield improvement of 16-20%. A pilot scale refining test using a Szego mill was performed and showed approximately 10% improvements in biomass digestibility. This suggests the possibility to scale up a mechanical refining technique to obtain similar enzymatic digestibility glucose yield enhancement as achieved by PFI milling and extrusion technologies. Proposed mechanisms of each mechanical refining technology are presented and reasons for improvements in biomass digestibility are discussed in this paper.}, journal={BIORESOURCE TECHNOLOGY}, author={Chen, Xiaowen and Kuhn, Erik and Wang, Wei and Park, Sunkyu and Flanegan, Keith and Trass, Olev and Tenlep, Lisette and Tao, Ling and Tucker, Melvin}, year={2013}, month={Nov}, pages={401–408} } @article{shin_hong_choi_park_2013, title={Crude oil production and classification of organic compounds on super-critical liquefaction with rice hull}, volume={18}, ISSN={["1976-3816"]}, DOI={10.1007/s12257-013-0122-x}, number={5}, journal={BIOTECHNOLOGY AND BIOPROCESS ENGINEERING}, author={Shin, JoungDu and Hong, Seung-Gill and Choi, Won-Sil and Park, SunKyu}, year={2013}, month={Sep}, pages={956–964} } @article{jones_venditti_park_jameel_koo_2013, title={Enhancement in enzymatic hydrolysis by mechanical refining for pretreated hardwood lignocellulosics}, volume={147}, ISSN={0960-8524}, url={http://dx.doi.org/10.1016/j.biortech.2013.08.030}, DOI={10.1016/j.biortech.2013.08.030}, abstractNote={This study investigated the effectiveness of mechanical refining to overcome the biomass recalcitrance barrier. Laboratory scale refining was conducted via PFI mill and valley beater refiners using green liquor and Kraft hardwood pulps. A strong positive correlation was determined between sugar recovery and water retention value. Refining produced significant improvements in enzymatic hydrolysis yield relative to unrefined substrates (e.g., sugar recovery increase from 67% to 90%, for 15% lignin Kraft pulp). A maximum absolute enzymatic hydrolysis improvement with refining was observed at enzymatic hydrolysis conditions that produced intermediate conversion levels. For a 91% target sugar conversion, PFI refining at 4000 revolutions allowed for a 32% reduction in enzyme charge for 15% lignin content hardwood Kraft pulp and 96 h hydrolysis time, compared to the unrefined material.}, journal={Bioresource Technology}, publisher={Elsevier BV}, author={Jones, Brandon W. and Venditti, Richard and Park, Sunkyu and Jameel, Hasan and Koo, Bonwook}, year={2013}, month={Nov}, pages={353–360} } @article{park_lee_koo_park_cosgrove_kim_2013, title={Monitoring Meso-Scale Ordering of Cellulose in Intact Plant Cell Walls Using Sum Frequency Generation Spectroscopy}, volume={163}, ISSN={["1532-2548"]}, DOI={10.1104/pp.113.225235}, abstractNote={Sum frequency generation spectroscopy is sensitive to the ordering of cellulose microfibrils in plant cell walls at the meso scale (nm to μm) that is important for cell wall architecture but cannot be probed by other spectroscopic or diffraction techniques. Sum frequency generation (SFG) vibration spectroscopy can selectively detect crystalline cellulose without spectral interference from cell wall matrix components. Here, we show that the cellulose SFG spectrum is sensitive to cellulose microfibril alignment and packing within the cell wall. SFG intensity at 2,944 cm−1 correlated well with crystalline cellulose contents of various regions of the Arabidopsis (Arabidopsis thaliana) inflorescence, while changes in the 3,320/2,944 cm−1 intensity ratio suggest subtle changes in cellulose ordering as tissues mature. SFG analysis of two cellulose synthase mutants (irx1/cesa8 and irx3/cesa7) indicates a reduction in cellulose content without evidence of altered cellulose structure. In primary cell walls of Arabidopsis, cellulose exhibited a characteristic SFG peak at 2,920 and 3,320 cm−1, whereas in secondary cell walls, it had peaks at 2,944 and 3,320 cm−1. Starch (amylose) gave an SFG peak at 2,904 cm−1 (CH methine) whose intensity increased with light exposure prior to harvest. Selective removal of matrix polysaccharides from primary cell walls by acid hydrolysis resulted in an SFG spectrum resembling that of secondary wall cellulose. Our results show that SFG spectroscopy is sensitive to the ordering of cellulose microfibrils in plant cell walls at the meso scale (nm to μm) that is important for cell wall architecture but cannot be probed by other spectroscopic or diffraction techniques.}, number={2}, journal={PLANT PHYSIOLOGY}, author={Park, Yong Bum and Lee, Christopher M. and Koo, Bon-Wook and Park, Sunkyu and Cosgrove, Daniel J. and Kim, Seong H.}, year={2013}, month={Oct}, pages={907–913} } @article{yu_jameel_chang_philips_park_2013, title={Quantification of bound and free enzymes during enzymatic hydrolysis and their reactivities on cellulose and lignocellulose}, volume={147}, ISSN={0960-8524}, url={http://dx.doi.org/10.1016/j.biortech.2013.08.010}, DOI={10.1016/j.biortech.2013.08.010}, abstractNote={Enzymatic hydrolysis of insoluble biomass is a surface reaction. Part of the enzyme adsorb on the surface of biomass, whereas the others stay in the liquid phase. In this study, three substrates (Avicel cellulose, bleached hardwood pulp, and green-liquor pretreated hardwood pulp) were used to study the reactivity of bound and free enzyme. In a continuous enzymatic hydrolysis, 35-65% initially added enzymes became bound enzymes, which were primarily responsible for enzymatic hydrolysis. The contribution from free enzymes became insignificant after a certain period of reaction time. SDS-PAGE analysis showed that CBH I was significantly decreased in the free enzyme, which might be the reason for the low digestibility of free enzymes due to the loss of synergistic effect. When Tween 80 was added during enzymatic hydrolysis, the digestibility of free enzyme on Avicel was greatly enhanced. However, the benefit of surfactant was not noticeable for lignocellulosic pulps, comparing to Avicel.}, journal={Bioresource Technology}, publisher={Elsevier BV}, author={Yu, Zhiying and Jameel, Hasan and Chang, Hou-min and Philips, Richard and Park, Sunkyu}, year={2013}, month={Nov}, pages={369–377} } @article{ren_meng_moore_chang_gou_park_2014, title={Thermogravimetric investigation on the degradation properties and combustion performance of bio-oils}, volume={152}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2013.11.028}, abstractNote={The degradation properties and combustion performance of raw bio-oil, aged bio-oil, and bio-oil from torrefied wood were investigated through thermogravimetric analysis. A three-stage process was observed for the degradation of bio-oils, including devolatilization of the aqueous fraction and light compounds, transition of the heavy faction to solid, and combustion of carbonaceous residues. Pyrolysis kinetics parameters were calculated via the reaction order model and 3D-diffusion model, and combustion indexes were used to qualitatively evaluate the thermal profiles of tested bio-oils for comparison with commercial oils such as fuel oils. It was found that aged bio-oil was more thermally instable and produced more combustion-detrimental carbonaceous solid. Raw bio-oil and bio-oil from torrefied wood had comparable combustion performance to fuel oils. It was considered that bio-oil has a potential to be mixed with or totally replace the fuel oils in boilers.}, journal={BIORESOURCE TECHNOLOGY}, author={Ren, Xueyong and Meng, Jiajia and Moore, Andrew M. and Chang, Jianmin and Gou, Jinsheng and Park, Sunkyu}, year={2014}, month={Jan}, pages={267–274} } @article{park_meng_lim_rojas_park_2013, title={Transformation of lignocellulosic biomass during torrefaction}, volume={100}, ISSN={["0165-2370"]}, DOI={10.1016/j.jaap.2012.12.024}, abstractNote={In this study, the effect of torrefaction on the chemical and structural transformation of lignocellulosic biomass was investigated using complementary analytical tools. It was observed that the acid-insoluble fraction was increased from approximately 30 to 38% and the methoxyl content was decreased to about half after torrefaction at 330 °C for 2.5 min. These results highlight the formation of condensed structures along with lignin transformation via demethoxylation. Solid-state NMR spectroscopy indicated that upon torrefaction the aromaticity increased from about 36 to 60%. For the sample torrefied at 330 °C, the non-protonated aromatic carbon fraction was found to be about 60% of total aromatic carbons, indicating the formation of large aromatic clusters. The complementary analyses used in this study are proposed as a suitable approach for the elucidation of chemical and structural transformation of biomass during thermal treatment.}, journal={JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS}, author={Park, Junyeong and Meng, Jiajia and Lim, Kwang Hun and Rojas, Orlando J. and Park, Sunkyu}, year={2013}, month={Mar}, pages={199–206} } @inbook{koo_park_2012, title={A Method to Evaluate Biomass Accessibility in Wet State Based on Thermoporometry}, ISBN={9781617799556 9781617799563}, url={http://dx.doi.org/10.1007/978-1-61779-956-3_8}, DOI={10.1007/978-1-61779-956-3_8}, abstractNote={The substrate accessibility to enzyme has been considered as one of the most important factors for biomass conversion. To avoid the irreversible collapse of pore structure during the drying of sample, the measurement needs to be performed in a wet state. In this report, a thermoporometry method based on DSC isothermal step procedure is explained in details. This detects the amount of nonfreezing bound water in a wet sample and the value is expressed into pore size distribution with the Gibbs-Thomson equation. Information on pore size distribution and pore volume can be used to evaluate biomass accessibility.}, booktitle={Biomass Conversion}, publisher={Humana Press}, author={Koo, Bon-Wook and Park, Sunkyu}, year={2012}, pages={83–89} } @article{srinivasan_adhikari_chattanathan_park_2012, title={Catalytic Pyrolysis of Torrefied Biomass for Hydrocarbons Production}, volume={26}, ISSN={["1520-5029"]}, DOI={10.1021/ef301469t}, abstractNote={A simple thermal pretreatment process called torrefaction has shown to be effective in improving the quality of pyrolysis oil in terms of chemical composition. The main objective of this study was to integrate torrefaction with fast pyrolysis process to produce high quality of bio-oil. In this study, the effects of four pyrolysis temperatures (450, 500, 550, and 600 °C) and shape selective zeolite catalyst (H+ZSM-5) on hydrocarbon yield were analyzed. Temperature and catalyst were found to be favorable for aromatic hydrocarbons from pyrolysis of torrefied biomass. The total carbon yield from catalytic pyrolysis of torrefied biomass was 1.45 times the total carbon yield from catalytic pyrolysis of untreated pine. Reaction mechanisms were proposed to understand the production of hydrocarbons from lignin and holocellulose derivatives.}, number={12}, journal={ENERGY & FUELS}, author={Srinivasan, Vaishnavi and Adhikari, Sushil and Chattanathan, Shyamsundar Ayalur and Park, Sunkyu}, year={2012}, month={Dec}, pages={7347–7353} } @article{sen_baheti_venditti_pawlak_park_bansal_2012, title={Cellulose Microfibril-water interaction as characterized by Isothermal thermogravimetric analysis and scanning electron microscopy}, volume={7}, ISSN={1930-2126}, url={http://dx.doi.org/10.15376/biores.7.4.4683-4703}, DOI={10.15376/biores.7.4.4683-4703}, abstractNote={Microfibrillated celluloses, liberated from macroscopic lignocellulosic fibers by mechanical means, are sub-fiber elements with lengths in the micron scale and diameters ranging from 10 to a few hundred nanometers. These materials have shown strong water interactions. This article describes an investigation and quantification of the ‘hard-to-remove (HR) water content’ in cellulose fibers and microfibrillated structures prepared from fully bleached softwood pulp (BSW). The fiber/fibril structure was altered by using an extended beating process (up to 300 minutes), and water interactions were determined with isothermal thermogravimetric analysis (TGA). Isothermal TGA is shown to be a convenient and insightful characterization method for fiber-water interactions for fibers and microfibrils at small sample size. In addition, scanning electron microscopic (SEM) images depict the differences between fibers and microfibrils with respect to beating time in the dried consolidated structures. Highly refined pulps with microfibrils were determined to have two critical drying points, i.e., two minima in the second derivative of weight versus time, not before reported in the literature. Also in this study, hard-to-remove (HR) water content is related to the area above the first derivative curve in the constant rate and falling rate drying zones. This measure of HR water correlates with a previous measurement method of HR water but is less ambiguous for materials that lack a constant drying rate zone. Blends of unbeaten fibers and microfibril containing samples were prepared and show potential as composite materials.}, number={4}, journal={BioResources}, publisher={BioResources}, author={Sen, Suman K. and Baheti, Vinit K. and Venditti, Richard A. and Pawlak, Joel J. and Park, Sunkyu and Bansal, Mukesh C.}, year={2012}, month={Aug}, pages={4683–4703} } @article{chen_venditti_jameel_park_2012, title={Enzymatic Hydrolysis of Recovered Office Printing Paper with Low Enzyme Dosages to Produce Fermentable Sugars}, volume={166}, ISSN={0273-2289 1559-0291}, url={http://dx.doi.org/10.1007/s12010-011-9498-2}, DOI={10.1007/s12010-011-9498-2}, number={5}, journal={Applied Biochemistry and Biotechnology}, publisher={Springer Science and Business Media LLC}, author={Chen, Hui and Venditti, Richard A. and Jameel, Hasan and Park, Sunkyu}, year={2012}, month={Jan}, pages={1121–1136} } @inproceedings{chen_gonzalez_phillips_venditti_jameel_park_2012, title={Exploring the potential of paper industry sludges for ethanol production}, booktitle={Proceeding of the 4th International Conference on Pulping, Papermaking and Biotechnology (ICPPB '12), vols. I and II}, author={Chen, H. and Gonzalez, R. and Phillips, R. and Venditti, R. and Jameel, H. and Park, S.}, year={2012}, pages={1040–1043} } @article{chen_tao_shekiro_mohaghaghi_decker_wang_smith_park_himmel_tucker_2012, title={Improved ethanol yield and reduced Minimum Ethanol Selling Price (MESP) by modifying low severity dilute acid pretreatment with deacetylation and mechanical refining: 1) Experimental}, volume={5}, ISSN={["1754-6834"]}, DOI={10.1186/1754-6834-5-60}, abstractNote={Historically, acid pretreatment technology for the production of bio-ethanol from corn stover has required severe conditions to overcome biomass recalcitrance. However, the high usage of acid and steam at severe pretreatment conditions hinders the economic feasibility of the ethanol production from biomass. In addition, the amount of acetate and furfural produced during harsh pretreatment is in the range that strongly inhibits cell growth and impedes ethanol fermentation. The current work addresses these issues through pretreatment with lower acid concentrations and temperatures incorporated with deacetylation and mechanical refining. The results showed that deacetylation with 0.1 M NaOH before acid pretreatment improved the monomeric xylose yield in pretreatment by up to 20% while keeping the furfural yield under 2%. Deacetylation also improved the glucose yield by 10% and the xylose yield by 20% during low solids enzymatic hydrolysis. Mechanical refining using a PFI mill further improved sugar yields during both low- and high-solids enzymatic hydrolysis. Mechanical refining also allowed enzyme loadings to be reduced while maintaining high yields. Deacetylation and mechanical refining are shown to assist in achieving 90% cellulose yield in high-solids (20%) enzymatic hydrolysis. When fermentations were performed under pH control to evaluate the effect of deacetylation and mechanical refining on the ethanol yields, glucose and xylose utilizations over 90% and ethanol yields over 90% were achieved. Overall ethanol yields were calculated based on experimental results for the base case and modified cases. One modified case that integrated deacetylation, mechanical refining, and washing was estimated to produce 88 gallons of ethanol per ton of biomass. The current work developed a novel bio-ethanol process that features pretreatment with lower acid concentrations and temperatures incorporated with deacetylation and mechanical refining. The new process shows improved overall ethanol yields compared to traditional dilute acid pretreatment. The experimental results from this work support the techno-economic analysis and calculation of Minimum Ethanol Selling Price (MESP) detailed in our companion paper.}, journal={BIOTECHNOLOGY FOR BIOFUELS}, author={Chen, Xiaowen and Tao, Ling and Shekiro, Joseph and Mohaghaghi, Ali and Decker, Steve and Wang, Wei and Smith, Holly and Park, Sunkyu and Himmel, Michael E. and Tucker, Melvin}, year={2012}, month={Aug} } @article{ago_jakes_johansson_park_rojas_2012, title={Interfacial Properties of Lignin-Based Electrospun Nanofibers and Films Reinforced with Cellulose Nanocrystals}, volume={4}, ISSN={1944-8244 1944-8252}, url={http://dx.doi.org/10.1021/am302008p}, DOI={10.1021/am302008p}, abstractNote={Sub-100 nm resolution local thermal analysis, X-ray photoelectron spectroscopy (XPS), and water contact angle (WCA) measurements were used to relate surface polymer distribution with the composition of electrospun fiber mats and spin coated films obtained from aqueous dispersions of lignin, polyvinyl alcohol (PVA), and cellulose nanocrystal (CNC). Defect-free lignin/PVA fibers were produced with radii which were observed to increase with lignin concentration and with the addition of CNCs. XPS and WCA results indicate a nonlinear relationship between the surface and the bulk compositions. A threshold around 50 wt % bulk composition was identified in which extensive partitioning of PVA and lignin components occurred on the surface below and above this value. In 75:25 wt % lignin/PVA solvent cast films, phase separated domains were observed. Using nanoscale thermal analyses, the continuous phase was determined to be lignin-rich and the discontinuous phase had a lignin/PVA dispersion. Importantly, the size of the phase separated domains was reduced by the addition of CNCs. When electrospun fiber surfaces were lignin-rich, the addition of CNCs affected their surfaces. In contrast, no surface effects were observed with the addition of CNCs in PVA-rich fibers. Overall, we highlight the importance of molecular interactions and phase separation on the surface properties of fibers from lignin as an abundant raw material for the fabrication of new functional materials.}, number={12}, journal={ACS Applied Materials & Interfaces}, publisher={American Chemical Society (ACS)}, author={Ago, Mariko and Jakes, Joseph E. and Johansson, Leena-Sisko and Park, Sunkyu and Rojas, Orlando J.}, year={2012}, month={Dec}, pages={6849–6856} } @article{ago_okajima_jakes_park_rojas_2012, title={Lignin-Based Electrospun Nanofibers Reinforced with Cellulose Nanocrystals}, volume={13}, ISSN={["1526-4602"]}, DOI={10.1021/bm201828g}, abstractNote={Lignin-based fibers were produced by electrospinning aqueous dispersions of lignin, poly(vinyl alcohol) (PVA), and cellulose nanocrystals (CNCs). Defect-free nanofibers with up to 90 wt % lignin and 15% CNCs were achieved. The properties of the aqueous dispersions, including viscosity, electrical conductivity, and surface tension, were examined and correlated to the electrospinnability and resulting morphology of the composite fibers. A ternary lignin-PVA-water phase diagram was constructed as a tool to rationalize the effect of mixing ratios on the dispersion electrospinability and morphology of the resulting fibers. The influence of reinforcing CNCs on the thermal properties of the multicomponent fibers was investigated by using thermal gravimetric analysis and differential scanning calorimetry. The thermal stability of the system was observed to increase owing to a strong interaction of the lignin-PVA matrix with the dispersed CNCs, mainly via hydrogen bonding, as observed in Fourier transform infrared spectroscopy experiments.}, number={3}, journal={BIOMACROMOLECULES}, author={Ago, Mariko and Okajima, Kunihiko and Jakes, Joseph E. and Park, Sunkyu and Rojas, Orlando J.}, year={2012}, month={Mar}, pages={918–926} } @article{barnette_lee_bradley_schreiner_park_shin_cosgrove_park_kim_2012, title={Quantification of crystalline cellulose in lignocellulosic biomass using sum frequency generation (SFG) vibration spectroscopy and comparison with other analytical methods}, volume={89}, ISSN={["1879-1344"]}, DOI={10.1016/j.carbpol.2012.04.014}, abstractNote={The non-centrosymmetry requirement of sum frequency generation (SFG) vibration spectroscopy allows the detection and quantification of crystalline cellulose in lignocellulose biomass without spectral interferences from hemicelluloses and lignin. This paper shows a correlation between the amount of crystalline cellulose in biomass and the SFG signal intensity. Model biomass samples were prepared by mixing commercially available cellulose, xylan, and lignin to defined concentrations. The SFG signal intensity was found sensitive to a wide range of crystallinity, but varied non-linearly with the mass fraction of cellulose in the samples. This might be due to the matrix effects such as light scattering and absorption by xylan and lignin, as well as the non-linear density dependence of the SFG process itself. Comparison with other techniques such as XRD, FT-Raman, FT-IR and NMR demonstrate that SFG can be a complementary and sensitive tool to assess crystalline cellulose in biomass.}, number={3}, journal={CARBOHYDRATE POLYMERS}, author={Barnette, Anna L. and Lee, Christopher and Bradley, Laura C. and Schreiner, Edward P. and Park, Yong Bum and Shin, Heenae and Cosgrove, Daniel J. and Park, Sunkyu and Kim, Seong H.}, year={2012}, month={Jul}, pages={802–809} } @article{xue_jameel_park_2012, title={Strategies to recycle enzymes and their impact on enzymatic hydrolysis for bioethanol production}, volume={7}, number={1}, journal={BioResources}, author={Xue, Y. and Jameel, H. and Park, S.}, year={2012}, pages={602–615} } @article{kim_park_harper_rials_2013, title={Structure and Thermomechanical Properties of Stretched Cellulose Films}, volume={128}, ISSN={["1097-4628"]}, DOI={10.1002/app.38149}, abstractNote={AbstractRegenerated and stretched cellulose films were investigated for structure and thermomechanical properties as a potential packaging material. Cellulose films were cast from lithium chloride/N, N‐dimethylacetamide and were stretched up to 30% in a dynamic mechanical analyzer sample holder. Wide‐angle X‐ray diffraction analysis indicated that the orientation factor was significantly increased due to stretching. In addition, the stretched films have a higher resistance to the thermal decomposition from thermo gravimetric analysis. The increased orientation of cellulose crystalline structure by the stretching process also increased the storage modulus of cellulose films characterized by dynamic mechanical analysis, which suggest that mechanical properties of cellulose films could be tuned during the stretching process. The α2 and α1 relaxations were found at 240 and 300°C, respectively, which are attributed to the micro‐Brownian motion of segments in amorphous region, and activation energies for relaxations were determined with the stretching levels. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013}, number={1}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={Kim, Jae-Woo and Park, Sunkyu and Harper, David P. and Rials, Timothy G.}, year={2013}, month={Apr}, pages={181–187} } @article{meng_park_tilotta_park_2012, title={The effect of torrefaction on the chemistry of fast-pyrolysis bio-oil}, volume={111}, ISSN={["0960-8524"]}, DOI={10.1016/j.biortech.2012.01.159}, abstractNote={Fast pyrolysis was performed on torrefied loblolly pine and the collected bio-oils were analyzed to compare the effect of the torrefaction treatment on their quality. The results of the analyses show that bio-oils produced from torrefied wood have improved oxygen-to-carbon ratios compared to those from the original wood with the penalty of a decrease in bio-oil yield. The extent of this improvement depends on the torrefaction severity. Based on the GC/MS analysis of the pyrolysis bio-oils, bio-oils produced from torrefied biomass show different compositions compared to that from the original wood. Specifically, the former becomes more concentrated in pyrolytic lignin with less water content than the latter. It was considered that torrefaction could be a potential upgrading method to improve the quality of bio-oil, which might be a useful feedstock for phenolic-based chemicals.}, journal={BIORESOURCE TECHNOLOGY}, author={Meng, Jiajia and Park, Junyeong and Tilotta, David and Park, Sunkyu}, year={2012}, month={May}, pages={439–446} } @inproceedings{yu_gwak_chang_park_jameel_2012, title={The impact of lignin on enzymatic hydrolysis of lignocellulosic biomass}, booktitle={Proceeding of the 4th International Conference on Pulping, Papermaking and Biotechnology (ICPPB '12), vols. I and II}, author={Yu, Z. Y. and Gwak, K. S. and Chang, H. M. and Park, S. and Jameel, H.}, year={2012}, pages={1143–1147} } @article{yu_jameel_chang_philips_park_2012, title={Evaluation of the factors affecting avicel reactivity using multi-stage enzymatic hydrolysis}, volume={109}, DOI={10.1002/bit.24386}, abstractNote={AbstractMulti‐stage and single‐stage enzymatic hydrolysis of cellulose (Avicel PH‐101) were conducted to investigate individual factors that affect the rate‐reducing kinetics of enzymatic hydrolysis. Understanding factors affecting enzymatic hydrolysis of Avicel will help improve hydrolysis of various biomasses. Product inhibition, enzyme deactivation, and the changes of substrate are potential factors that can affect the hydrolysis efficiency of Avicel. Multi‐stage enzymatic hydrolysis resulted in 36.9% and 25.4% higher carbohydrate conversion as compared to a single‐stage enzymatic hydrolysis with an enzyme loading of 5 and 20 FPU/g in a 96 h reaction. However, a decline in carbohydrate conversion of 1.6% and 2.6% was observed through each stage with 5 and 20 FPU/g, respectively. This indicated that the substrate became more recalcitrant as hydrolysis progressed. The decreased reactivity was not due to crystallinity because no significant change in crystallinity was detected by X‐ray diffraction. Product inhibition was significant at low enzyme loading, while it was marginal at high enzyme loading. Therefore, product inhibition can only partially explain this decreased conversion. Another important factor, enzyme deactivation, contributed to 20.3% and 25.4% decrease in the total carbohydrate conversion of 96 h hydrolysis with 5 and 20 FPU/g, respectively. This work shows that an important reason for the decreased Avicel digestibility is the effect of enzyme blockage, which refers to the enzymes that irreversibly adsorb on accessible sites of substrate. About 45.3% and 63.2% of the total decreased conversion at the end of the 8th stage with 5 and 20 FPU/g, respectively, was due to the presence of irreversibly adsorbed enzymes. This blockage of active sites by enzymes has been speculated by other researchers, but this article shows further evidence of this effect. Biotechnol. Bioeng. 2012; 109:1131–1139. © 2011 Wiley Periodicals, Inc.}, number={5}, journal={Biotechnology and Bioengineering}, author={Yu, Z. Y. and Jameel, H. and Chang, H. M. and Philips, R. and Park, Sunkyu}, year={2012}, pages={1131–1139} } @article{hubbe_wu_rojas_park_2011, title={Permeation of a cationic polyelectrolyte into mesoporous silica: Part 3. Using adsorption isotherms to elucidate streaming potential results}, volume={381}, ISSN={0927-7757}, url={http://dx.doi.org/10.1016/j.colsurfa.2010.12.052}, DOI={10.1016/j.colsurfa.2010.12.052}, abstractNote={Parts 1 and 2 of this series showed that the streaming potential of silica gel particles in aqueous media can be profoundly affected by their exposure to solutions of a cationic polyelectrolyte. The extent of the change in streaming potential depended on such variables as pH, salt concentration, polyelectrolyte molecular mass and concentration, pore size, and time. However, questions arose concerning the relationship between the observed changes in streaming potential and the net amount of adsorbed polyelectrolyte. Some preliminary experiments suggested that, compared to adsorption tests, the streaming potential method may be much more sensitive to the permeation of minor amounts of oligomeric impurities into the network of mesopores in the substrate. The present article follows up on these findings, evaluating adsorption isotherms for the same systems that earlier had been examined by the streaming potential method. In contrast to the earlier work, it was possible to interpret the isotherms based on a model in which adsorbate interacts with a set of equivalent, non-interacting adsorption sites. The kinetics of adsorption were time-dependent and diffusion limited. The polymer adsorbed amount was controlled by both the pore size and the surface area. The highest adsorption amount, based on mass of the substrate, was achieved when using silica gel having an intermediate pore size (15 nm) at a relatively high solution concentration of very-low-mass polyelectrolyte. The results could be fit well to a Langmuir model of the adsorption process.}, number={1-3}, journal={Colloids and Surfaces A: Physicochemical and Engineering Aspects}, publisher={Elsevier BV}, author={Hubbe, Martin A. and Wu, Ning and Rojas, Orlando J. and Park, Sunkyu}, year={2011}, month={May}, pages={1–6} } @article{koo_treasure_jameel_phillips_chang_park_2011, title={Reduction of enzyme dosage by oxygen delignification and mechanical refining for enzymatic hydrolysis of green liquor-pretreated hardwood}, volume={165}, DOI={10.1007/s12010-011-9301-4}, abstractNote={In this study, a strategy to reduce enzyme dosage is evaluated by applying two post-treatments, oxygen delignification and mechanical refining. The sugar conversion for GL12 substrates was increased from 51.5% to 77.9% with post-treatments at the enzyme dosage of 10 FPU. When the amount of enzyme was reduced to 5 FPU with post-treatments, the conversion of 71.8% was obtained, which was significant higher than the conversion without any post-treatment using 10 FPU (51.5%). This clearly demonstrates the benefit of post-treatments that allows more than 50% of enzyme reduction at the same level of enzymatic conversion. Enzyme-accessible surface area and pore volume were evaluated by Simons' staining and DSC thermoporometry methods, and strong correlations were found with the sugar conversion.}, number={3-4}, journal={Applied Biochemistry and Biotechnology}, author={Koo, B. W. and Treasure, T. H. and Jameel, H. and Phillips, R. B. and Chang, H. M. and Park, Sunkyu}, year={2011}, pages={832–844} } @article{barnette_bradley_veres_schreiner_park_park_park_kim_2011, title={Selective Detection of Crystalline Cellulose in Plant Cell Walls with Sum-Frequency-Generation (SFG) Vibration Spectroscopy}, volume={12}, ISSN={["1525-7797"]}, DOI={10.1021/bm200518n}, abstractNote={The selective detection of crystalline cellulose in biomass was demonstrated with sum-frequency-generation (SFG) vibration spectroscopy. SFG is a second-order nonlinear optical response from a system where the optical centrosymmetry is broken. In secondary plant cell walls that contain mostly cellulose, hemicellulose, and lignin with varying concentrations, only certain vibration modes in the crystalline cellulose structure can meet the noninversion symmetry requirements. Thus, SFG can be used to detect and analyze crystalline cellulose selectively in lignocellulosic biomass without extraction of noncellulosic species from biomass or deconvolution of amorphous spectra. The selective detection of crystalline cellulose in lignocellulosic biomass is not readily achievable with other techniques such as XRD, solid-state NMR, IR, and Raman analyses. Therefore, the SFG analysis presents a unique opportunity to reveal the cellulose crystalline structure in lignocellulosic biomass.}, number={7}, journal={BIOMACROMOLECULES}, author={Barnette, Anna L. and Bradley, Laura C. and Veres, Brandon D. and Schreiner, Edward P. and Park, Yong Bum and Park, Junyeong and Park, Sunkyu and Kim, Seong H.}, year={2011}, month={Jul}, pages={2434–2439} } @article{bozell_black_myers_cahill_miller_park_2011, title={Solvent fractionation of renewable woody feedstocks: Organosolv generation of biorefinery process streams for the production of biobased chemicals}, volume={35}, ISSN={["0961-9534"]}, DOI={10.1016/j.biombioe.2011.07.006}, abstractNote={A new organosolv biomass fractionation process (Clean Fractionation, CF) for the separation of lignocellulosic raw material into cellulose, hemicellulose and lignin has been developed. The lignocellulosic material is separated with a ternary mixture of methyl isobutyl ketone, ethanol and water in the presence of an acid promoter, which selectively dissolves lignin and hemicellulose, leaving cellulose as an undissolved solid. The resulting single phase liquor is treated with water giving an organic phase containing lignin and an aqueous phase containing hemicellulose. For woody feedstocks, the yield of the cellulose fraction across all separations averaged 47.7 wt% (±1.1). Representative separations gave cellulose fractions with average Klason lignin contents of 2.0% at acid concentrations of 0.1 M H2SO4 or greater. Little or no galactose, mannose or arabinose is observed in the cellulose, and at an acid concentration of 0.2 M, average xylose contents as low as 0.22% were observed. Average glucan contents for representative cellulose samples of 92.7% were observed, and rose as high as 98.2% for separations using 0.2 M H2SO4. Glucan contents as high as 97% were also observed if the cellulose was bleached using either a QPD or QPDE sequence. The average yield of the lignin fraction was 18.3 wt%. Representative lignin samples gave an average Klason lignin value of 91% with selected lignin samples exhibiting residual sugar levels of <0.5%. The aqueous hemicellulose fraction contains a higher level of non-sugar components, but can be purified by ion exchange chromatography.}, number={10}, journal={BIOMASS & BIOENERGY}, author={Bozell, Joseph J. and Black, Stuart K. and Myers, Michele and Cahill, Deborah and Miller, W. Paul and Park, Sunkyu}, year={2011}, month={Oct}, pages={4197–4208} } @article{yu_jameel_chang_park_2011, title={The effect of delignification of forest biomass on enzymatic hydrolysis}, volume={102}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2011.07.001}, abstractNote={The effect of delignification methods on enzymatic hydrolysis of forest biomass was investigated using softwood and hardwood that were pretreated at an alkaline condition followed by sodium chlorite or ozone delignification. Both delignifications improved enzymatic hydrolysis especially for softwood, while pretreatment alone was found effective for hardwood. High enzymatic conversion was achieved by sodium chlorite delignification when the lignin content was reduced to 15%, which is corresponding to 0.30-0.35 g/g accessible pore volume, and further delignification showed a marginal effect. Sample crystallinity index increased with lignin removal, but it did not show a correlation with the overall carbohydrate conversion of enzymatic hydrolysis.}, number={19}, journal={BIORESOURCE TECHNOLOGY}, author={Yu, Zhiying and Jameel, Hasan and Chang, Hou-min and Park, Sunkyu}, year={2011}, month={Oct}, pages={9083–9089} } @article{park_baker_himmel_parilla_johnson_2010, title={Cellulose crystallinity index: measurement techniques and their impact on interpreting cellulase performance}, volume={3}, ISSN={["1754-6834"]}, DOI={10.1186/1754-6834-3-10}, abstractNote={Abstract Although measurements of crystallinity index (CI) have a long history, it has been found that CI varies significantly depending on the choice of measurement method. In this study, four different techniques incorporating X-ray diffraction and solid-state 13C nuclear magnetic resonance (NMR) were compared using eight different cellulose preparations. We found that the simplest method, which is also the most widely used, and which involves measurement of just two heights in the X-ray diffractogram, produced significantly higher crystallinity values than did the other methods. Data in the literature for the cellulose preparation used (Avicel PH-101) support this observation. We believe that the alternative X-ray diffraction (XRD) and NMR methods presented here, which consider the contributions from amorphous and crystalline cellulose to the entire XRD and NMR spectra, provide a more accurate measure of the crystallinity of cellulose. Although celluloses having a high amorphous content are usually more easily digested by enzymes, it is unclear, based on studies published in the literature, whether CI actually provides a clear indication of the digestibility of a cellulose sample. Cellulose accessibility should be affected by crystallinity, but is also likely to be affected by several other parameters, such as lignin/hemicellulose contents and distribution, porosity, and particle size. Given the methodological dependency of cellulose CI values and the complex nature of cellulase interactions with amorphous and crystalline celluloses, we caution against trying to correlate relatively small changes in CI with changes in cellulose digestibility. In addition, the prediction of cellulase performance based on low levels of cellulose conversion may not include sufficient digestion of the crystalline component to be meaningful.}, journal={BIOTECHNOLOGY FOR BIOFUELS}, author={Park, Sunkyu and Baker, John O. and Himmel, Michael E. and Parilla, Philip A. and Johnson, David K.}, year={2010}, month={May} } @article{hubbe_wu_rojas_park_2010, title={Permeation of a cationic polyelectrolyte into mesoporous silica. Part 2. Effects of time and pore size on streaming potential}, volume={364}, ISSN={0927-7757}, url={http://dx.doi.org/10.1016/j.colsurfa.2010.05.005}, DOI={10.1016/j.colsurfa.2010.05.005}, abstractNote={Streaming potential tests were carried out to determine effects of time and pore size in the adsorption and desorption from aqueous suspensions of cationic polyelectrolytes on silica gel particles. Results in Part 1 of this series showed that the adsorption of cationic polyelectrolytes exposed to mesoporous silica gels can be highly dependent on pH, the polyelectrolyte's molecular mass, and the solution's electrical conductivity. Also, the observed changes in streaming potential indicated that the adsorption tended to be relatively slow and incomplete under the conditions of analysis. The present results indicate that the rate of change of streaming potential is proportional to the logarithm of exposure time. The related changes in adsorbed amounts of polyelectrolyte were below the detection limits of typical polyelectrolyte titration procedures. Contrasting charge behaviors were observed on the exterior vs. interior surfaces of silica gel particles as a function of pore size, electrical conductivity, and polyelectrolyte molecular mass. Increasing ionic strength tended to enhance the effect of adsorption of high-mass cationic polymers on the outer surfaces, but produced only a relatively small effect on streaming potential related to their permeation into silica gel (nominal pore sizes of 6 nm or 30 nm). Adsorption of very-low-mass cationic polymer onto the outer surfaces and inside the 6 nm pore size silica gel appeared to be maximized at an intermediate salt level. Finally, electrokinetic tests were used for the first time in a protocol designed to provide evidence of polyelectrolyte desorption from the interiors of mesoporous materials.}, number={1-3}, journal={Colloids and Surfaces A: Physicochemical and Engineering Aspects}, publisher={Elsevier BV}, author={Hubbe, Martin A. and Wu, Ning and Rojas, Orlando J. and Park, Sunkyu}, year={2010}, month={Jul}, pages={7–15} } @article{park_johnson_ishizawa_parilla_davis_2009, title={Measuring the crystallinity index of cellulose by solid state 13C nuclear magnetic resonance}, volume={16}, ISSN={0969-0239 1572-882X}, url={http://dx.doi.org/10.1007/s10570-009-9321-1}, DOI={10.1007/s10570-009-9321-1}, number={4}, journal={Cellulose}, publisher={Springer Science and Business Media LLC}, author={Park, Sunkyu and Johnson, David K. and Ishizawa, Claudia I. and Parilla, Philip A. and Davis, Mark F.}, year={2009}, month={Jun}, pages={641–647} } @article{wu_hubbe_rojas_park_2010, title={Permeation of a cationic polyelectrolyte into meso-porous silica: Part 1. Factors affecting changes in streaming potential}, volume={364}, ISSN={0927-7757}, url={http://dx.doi.org/10.1016/j.colsurfa.2009.11.042}, DOI={10.1016/j.colsurfa.2009.11.042}, abstractNote={A recently developed streaming potential (SP) strategy was used for the first time to investigate factors affecting permeation of the cationic polyelectrolyte poly-(diallyldimethylammonium chloride) from aqueous solution into silica gel particles. Factors affecting cationic polyelectrolyte permeation were considered, including polyelectrolyte dosage, molecular mass, solution pH, and electrical conductivity. Samples were equilibrated for approximately 20 h before testing. The magnitude of change in streaming potential, which was taken as evidence of permeation, increased with increasing polyelectrolyte dosage, with decreasing molecular mass, and with decreasing pH in the range 11 to 3. The pH effect supports a mechanism in which excessively strong electrostatic attraction between the polyelectrolyte and the substrate immobilizes macromolecules at or near the entrances to the pore network, thus inhibiting permeation of like-charged macromolecules. The same mechanism is consistent with observations that permeation increased with increasing electrical conductivity, though the latter observation also could be explained in terms of conformational changes.}, number={1-3}, journal={Colloids and Surfaces A: Physicochemical and Engineering Aspects}, publisher={Elsevier BV}, author={Wu, Ning and Hubbe, Martin A. and Rojas, Orlando J. and Park, Sunkyu}, year={2010}, month={Jul}, pages={1–6} } @article{wu_hubbe_rojas_park_2009, title={Permeation of polyelectrolytes and other solutes into the pore spaces of water-swollen cellulose: A review}, volume={4}, number={3}, journal={BioResources}, publisher={Link}, author={Wu, N. and Hubbe, M.A. and Rojas, O.J. and Park, S.}, year={2009}, pages={1222–1262} } @article{park_venditti_jameel_pawlak_2007, title={Hard-to-remove water in cellulose fibers characterized by thermal analysis: A model for the drying of wood-based fibers}, volume={6}, number={7}, journal={TAPPI Journal}, author={Park, S. and Venditti, R. A. and Jameel, H. and Pawlak, J. J.}, year={2007}, pages={10–16} } @article{park_venditti_jameel_pawlak_2007, title={Studies of the heat of vaporization of water associated with cellulose fibers characterized by thermal analysis}, volume={14}, ISSN={["0969-0239"]}, DOI={10.1007/s10570-007-9108-1}, number={3}, journal={CELLULOSE}, author={Park, Sunkyu and Venditti, Richard A. and Jameel, Hasan and Pawlak, Joel J.}, year={2007}, month={Jun}, pages={195–204} } @article{park_venditti_jameel_pawlak_2006, title={A novel method to evaluate fibre hornification by high resolution thermogravimetric analysis}, volume={59}, number={6}, journal={Appita Journal}, author={Park, S. and Venditti, R. A. and Jameel, H. and Pawlak, J. J.}, year={2006}, pages={481–485} } @article{park_venditti_jameel_pawlak_2006, title={Changes in pore size distribution during the drying of cellulose fibers as measured by differential scanning calorimetry}, volume={66}, ISSN={0144-8617}, url={http://dx.doi.org/10.1016/j.carbpol.2006.02.026}, DOI={10.1016/j.carbpol.2006.02.026}, abstractNote={Changes in pore size distribution during the drying of cellulose fibers were determined using differential scanning calorimetry (DSC) with an isothermal step melting procedure. Softwood bleached kraft pulp at various moisture ratios were generated from partial drying in a thermogravimetric analyzer and then analyzed in a DSC. The pore size distribution was calculated using the Gibbs–Thomson equation and specific melting point depression of water detected by DSC. It was observed that larger pores collapse first followed by the sequential collapse of smaller pores. It is suggested that pore wall collapse resistance is the primary factor that determines which size pores close. The average measured pore size in the fiber wall of the never dried fiber was calculated to be about 80 nm and reduced with drying of the fibers. A constant pore size of about 20 nm was observed at moisture ratios below 0.3 g/g, which corresponds to one-to-two layers of non-freezing bound water tightly bound to the surface.}, number={1}, journal={Carbohydrate Polymers}, publisher={Elsevier BV}, author={Park, S and Venditti, R and Jameel, H and Pawlak, J}, year={2006}, month={Oct}, pages={97–103} } @article{hubbe_rojas_lee_park_wang_2007, title={Distinctive electrokinetic behavior of nanoporous silica particles treated with cationic polyelectrolyte}, volume={292}, ISSN={["0927-7757"]}, DOI={10.1016/j.colsurfa.2006.06.034}, abstractNote={In this study we show, for the first time, that the streaming potential of aqueous suspensions of nanoporous silica gel, after treatment with the cationic polyelectrolyte poly-diallyldimethylammonium chloride (poly-DADMAC), can depend very strongly on the concentration of background electrolyte. An increase in the electrical conductivity from 60 to 1000 μS/cm resulted in an approximately 1000-fold increase in the amount of poly-DADMAC that was required to reach an endpoint of zero streaming potential. Results were explained by two contributions to the overall electrokinetic behavior—one due to the outer surfaces and another due to the interior surfaces of nanopore spaces that were inaccessible to the polyelectrolytes. Experiments with cyclical changes in salt content revealed a high degree of reversibility; such observations help to rule out explanations based on salt-induced desorption or enhancement of pore penetration. Supplementary tests with non-porous glass fibers showed no evidence of the distinctive electrokinetic behavior observed in the case of nanoporous particles. Effects of polymer molecular mass and pH, evaluated under similar experimental conditions, agreed with well-established trends.}, number={2-3}, journal={COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS}, author={Hubbe, Martin A. and Rojas, Orlando J. and Lee, Sa Yong and Park, Sunkyu and Wang, Yun}, year={2007}, month={Jan}, pages={271–278} } @article{park_lee_2006, title={Influence of the calendering conditions on opacity and quantitative evaluation of the z-directional density variation by image analysis}, volume={21}, ISSN={2000-0669 0283-2631}, url={http://dx.doi.org/10.3183/npprj-2006-21-02-p211-215}, DOI={10.3183/npprj-2006-21-02-p211-215}, abstractNote={Article Influence of the calendering conditions on opacity and quantitative evaluation of the z-directional density variation by image analysis was published on May 1, 2006 in the journal Nordic Pulp & Paper Research Journal (volume 21, issue 2).}, number={2}, journal={Nordic Pulp & Paper Research Journal}, publisher={Walter de Gruyter GmbH}, author={Park, Sunkyu and Lee, Hak Lae}, year={2006}, month={May}, pages={211–215} } @article{park_venditti_abrecht_jameel_pawlak_lee_2007, title={Surface and pore structure modification of cellulose fibers through cellulase treatment}, volume={103}, ISSN={["0021-8995"]}, DOI={10.1002/app.25457}, abstractNote={AbstractThe surface and pore structure of cellulose fibers have a significant impact on the properties and performance in applications. Cellulase enzymatic hydrolysis of cellulose fibers can result in changes to the surface and pore structure, thus providing a useful tool for fiber modification. This research characterizes these changes using various test methods such as fiber dimension, water retention value (WRV), hard‐to‐remove (HR) water content, freezing and nonfreezing bound water content, polymer adsorption, and crystallinity index. For a high‐dosage cellulase treatment (600 U/g dry solid), the fiber length was significantly decreased and the fibers were “cut” in the cross direction, not in the axial direction. The swelling capacities as measured by the WRV and HR water content increased for the high‐dosage treatment. Three independent measurements (nonfreezing bound water, polymer adsorption, and crystallinity index) are in good agreement with the statement that the amorphous regions of cellulose fibers are a more readily available substrate relative to crystalline regions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3833–3839, 2007}, number={6}, journal={JOURNAL OF APPLIED POLYMER SCIENCE}, author={Park, Sunkyu and Venditti, Richard A. and Abrecht, David G. and Jameel, Hasan and Pawlak, Joel J. and Lee, Jung M.}, year={2007}, month={Mar}, pages={3833–3839} } @article{park_venditti_jameel_pawlak_2006, title={Hard to remove water in cellulose fibers characterized by high resolution thermogravimetric analysis - methods development}, volume={13}, ISSN={0969-0239 1572-882X}, url={http://dx.doi.org/10.1007/s10570-005-9009-0}, DOI={10.1007/s10570-005-9009-0}, number={1}, journal={Cellulose}, publisher={Springer Science and Business Media LLC}, author={Park, Sunkyu and Venditti, Richard A. and Jameel, Hasan and Pawlak, Joel J.}, year={2006}, month={Nov}, pages={23–30} } @inproceedings{park_venditti_pawlak_jameel_2005, title={High resolution thermo-gravimetric analysis of pulp drying}, booktitle={Advances in Paper Science and Technology: Transactions of the 13th Fundamental research symposium, vols 1-3}, author={Park, S. and Venditti, R. A. and Pawlak, J. J. and Jameel, H.}, year={2005}, pages={161–186} } @article{park_venditti_jameel_pawlak_2005, title={The effect of fibre properties on fibre fractionation using a hydrocyclone}, volume={31}, number={3}, journal={Journal of Pulp and Paper Science}, author={Park, S. and Venditti, R. A. and Jameel, H. and Pawlak, J. J.}, year={2005}, pages={132–137} } @article{lee_lee_park_2000, title={Evaluation of the nip pressure profile and analysis of heat transfer in soft nip calender}, volume={32}, number={2}, journal={Journal of Korea Technical Association of the Pulp and Paper Industry}, author={Lee, S.Y. and Lee, H.L. and Park, S.}, year={2000}, pages={85–88} } @misc{hubbe_park_park, title={Cellulosic substrates for removal of pollutants from aqueous systems: A review. Part 4. dissolved petrochemical compounds}, volume={9}, number={4}, journal={BioResources}, author={Hubbe, M. A. and Park, J. and Park, S.}, pages={7782–7925} } @article{ago_jakes_johansson_park_rojas, title={Interfacial properties of lignin-based electrospun nanofibers and films reinforced with cellulose nanocrystals}, volume={4}, number={12}, journal={ACS Applied Materials & Interfaces}, author={Ago, M. and Jakes, J. E. and Johansson, L. S. and Park, S. and Rojas, O. J.}, pages={6848–6855} }