@article{hopkins_knappe_2024, title={Predicting per- and polyfluoroalkyl substances removal in pilot-scale granular activated carbon adsorbers from rapid small-scale column tests}, volume={6}, ISSN={["2577-8161"]}, url={https://doi.org/10.1002/aws2.1369}, DOI={10.1002/aws2.1369}, abstractNote={AbstractPer‐ and polyfluoroalkyl substances (PFAS) occur widely in drinking water, and consumption of contaminated drinking water is an important human exposure route. Granular activated carbon (GAC) adsorption can effectively remove PFAS from water. To support the design of GAC treatment systems, a rapid bench‐scale testing procedure and scale‐up approach are needed to assess the effects of GAC type, background water matrix, and empty bed contact time (EBCT) on GAC use rates. The overarching goal of this study was to predict PFAS breakthrough curves obtained at the pilot‐scale from rapid small‐scale column test (RSSCT) data. The scale‐up protocol was developed for pilot data obtained with coagulated/settled surface water (TOC = 2.3 mg/L), three GACs, and two EBCTs. Between 7 and 11 PFAS breakthrough curves were available for each pilot column. RSSCT designs were investigated that assumed intraparticle diffusivity is independent of GAC particle size (i.e., constant diffusivity [CD]) or linearly dependent on GAC particle size (i.e., proportional diffusivity [PD]). CD‐RSSCTs effectively predicted the bed volumes of water that could be treated at the pilot‐scale to reach 50% breakthrough (BV50%) of individual PFAS. In contrast, PD‐RSSCTs overpredicted BV50% obtained at the pilot‐scale by a factor of ~2–3. The shape of PFAS breakthrough curves obtained with CD‐RSSCTs deviated from those obtained at the pilot‐scale, indicating that intraparticle diffusivity was dependent on GAC particle diameter (dp). Using the pore surface diffusion model (PSDM), intraparticle diffusivity was found to be proportional to (dp)0.25 when considering data up to about 70% PFAS breakthrough. This proportionality factor can be used to design RSSCTs or scale up existing CD‐RSSCT data using the PSDM. Using pilot‐scale data obtained with groundwater and wastewater‐impacted groundwater as well as with additional GACs, the developed RSSCT scale‐up approach was validated for PFAS breakthrough percentages up to 70%. The presented methodology permits the rapid prediction of GAC use rates for PFAS removal.}, number={2}, journal={AWWA WATER SCIENCE}, author={Hopkins, Zachary R. and Knappe, Detlef R. U.}, year={2024}, month={Mar} }
 @article{petre_genereux_koropeckyj-cox_knappe_duboscq_gilmore_hopkins_2021, title={Per- and Polyfluoroalkyl Substance (PFAS) Transport from Groundwater to Streams near a PFAS Manufacturing Facility in North Carolina, USA}, volume={55}, ISSN={["1520-5851"]}, url={https://doi.org/10.1021/acs.est.0c07978}, DOI={10.1021/acs.est.0c07978}, abstractNote={We quantified per- and polyfluoroalkyl substance (PFAS) transport from groundwater to five tributaries of the Cape Fear River near a PFAS manufacturing facility in North Carolina (USA). Hydrologic and PFAS data were coupled to quantify PFAS fluxes from groundwater to the tributaries. Up to 29 PFAS were analyzed, including perfluoroalkyl acids and recently identified fluoroethers. Total quantified PFAS (ΣPFAS) in groundwater was 20–4773 ng/L (mean = 1863 ng/L); the range for stream water was 426–3617 ng/L (mean = 1717 ng/L). Eight PFAS constituted 98% of ΣPFAS; perfluoro-2-(perfluoromethoxy)propanoic acid (PMPA) and hexafluoropropylene oxide dimer acid (GenX) accounted for 61%. For PFAS discharge from groundwater to one tributary, values estimated from stream water measurements (18 ± 4 kg/yr) were similar to those from groundwater measurements in streambeds (22–25 ± 5 kg/yr). At baseflow, 32 ± 7 kg/yr of PFAS discharged from groundwater to the five tributaries, eventually reaching the Cape Fear River. Given the PFAS emission timeline at the site, groundwater data suggest the abundant fluoroethers moved through the subsurface to streams in ≪50 yr. Discharge of contaminated groundwater may lead to long-term contamination of surface water and impacts on downstream drinking water supplies. This work addresses a gap in the PFAS literature: quantifying PFAS mass transfer between groundwater and surface water using field data.}, number={9}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, publisher={American Chemical Society (ACS)}, author={Petre, Marie-Amelie and Genereux, David P. and Koropeckyj-Cox, Lydia and Knappe, Detlef R. U. and Duboscq, Sandrine and Gilmore, Troy E. and Hopkins, Zachary R.}, year={2021}, month={May}, pages={5848–5856} }
 @misc{dodds_alexander_kirkwood_foster_hopkins_knappe_baker_2021, title={From Pesticides to Per- and Polyfluoroalkyl Substances: An Evaluation of Recent Targeted and Untargeted Mass Spectrometry Methods for Xenobiotics}, volume={93}, ISSN={["1520-6882"]}, url={https://doi.org/10.1021/acs.analchem.0c04359}, DOI={10.1021/acs.analchem.0c04359}, abstractNote={Environmental analysis of xenobiotics is a challenging yet necessary undertaking to characterize pollution levels, assess the effectiveness of remediation interventions, and prevent adverse environmental and health outcomes. Xenobiotics are concerning from an environmental perspective due to their chemical persistence, toxicity to humans and wildlife, and prolific use in agricultural and industrial applications.1 Many xenobiotics are persistent organic pollutants (POPs), and the number of POPs listed in the Stockholm Convention is}, number={1}, journal={ANALYTICAL CHEMISTRY}, publisher={American Chemical Society (ACS)}, author={Dodds, James N. and Alexander, Nancy Lee M. and Kirkwood, Kaylie I and Foster, MaKayla R. and Hopkins, Zachary R. and Knappe, Detlef R. U. and Baker, Erin S.}, year={2021}, month={Jan}, pages={641–656} }