@article{wang_chen_gratzl_2005, title={Dechlorination of chlorophenols found in pulp bleach plant E-1 effluents by advanced oxidation processes}, volume={96}, ISSN={["1873-2976"]}, DOI={10.1016/j.biortech.2004.08.011}, abstractNote={Studies were conducted on the response of 2,4,6-trichlorophenol (1), 2,3,4,5-tetrachloro-phenol (2) and 4,5-dichloroguaiacol (3) toward advanced oxidation processes, such as UV-, O2/UV-, H2O2/UV-, O3/UV- and O3-H2O2/UV-photolyses with irradiation of 254 nm photons. The compounds 1-3 are among the chlorophenols found in the Kraft-pulp bleach plant E-1 effluents. The studies were extended to treatment of these compounds with ozonation and O3-H2O2 oxidation systems in alkaline aqueous solution. Except for the O2/UV-photolysis of 1 and H2O2/UV-photolysis of 2, the dechlorination of 1-3 by O2/UV- and H2O2/UV-potolyses were less effective than the corresponding N2UV-potolysis of 1-3. Guaiacol-type chlorophenols were more readily able to undergo dechlorination than non-guaiacol type chlorophenols by N2/UV-, O2/UV- and H2O2/UV-potolyses. In addition, the efficiency for the dechlorination of 1-3 by N2/UV-, O2/UV- and H2O2/UV-potolyses appeared to be dependent upon the inductive and resonance effects of substituents as well as number and position of chlorine substituent in the aromatic ring of the compounds. The dechlorination of 2 by treatment with O3 alone is slightly more effective than the corresponding the O3/UV-photlysis, whereas the dechlorination of 2 by treatment with the combination of O3 and H2O2 was slightly less effective than the corresponding O3-H2O2/UV-photolysis. In contrast, the dechlorination of 3 on treatment with O3 alone was slightly less effective than the corresponding the O3/UV-photolysis, whereas the dechlorination of 3 on treatment with the combination of O3 and H2O2 was slightly more effective than the corresponding the O3-H2O2/UV-photolysis. In the dechlorination of 2 and 3, chemical species derived from ozone and hydrogen peroxide in alkaline solution were dominant reactions in the O3/UV- and O3-H2O2/UV-photolysis systems as in the O3 and O3-H2O2 oxidation systems. Possible dechlorination mechanisms involved were discussed on the basis of kinetic data.}, number={8}, journal={BIORESOURCE TECHNOLOGY}, author={Wang, R and Chen, CL and Gratzl, JS}, year={2005}, month={May}, pages={897–906} }
 @article{wang_chen_gratzl_2004, title={Ozonation of pine kraft lignin in alkaline solution. Part 1: Ozonation, characterization of kraft lignin and its ozonated preparations}, volume={58}, ISSN={["1437-434X"]}, DOI={10.1515/HF.2004.116}, abstractNote={Abstract Pine kraft lignin was purified to obtain a kraft lignin preparation (KL) with weight average molecular mass (M w ) of 5500. The KL was then ozonated with an ozone-air stream containing 2–2.5% of ozone in 0.1 M sodium hydroxide solution to prepare ozonated kraft lignin preparations with ozone consumption of 10, 25, 30 and 40% per KL; Oz-10-KL, Oz-25-KL, Oz-30-KL and Oz-40-KL, respectively. The pH of reaction mixture was decreased with increasing ozone consumption, while the carboxylic acid content and the M w of resulting ozonated lignins increase with increasing ozone consumption. The KL and its ozonated preparations were then characterized by elemental composition, functional group analysis, molecular mass distribution and nitrobenzene-K 4 MnO 4 oxidation. The results showed that the KL extensively undergoes oxidative cleavage of both side chains and aromatic moieties without decrease in the M w as well as dehydrogenationive coupling of phenolic degraded fragments by active oxygen radical species, such as hydroperoxyl and hydroxyl radicals. The formation of these active oxygen radical species are produced by way of a series of reactions initiated by the reaction of ozone with hydroxide anions at pH range of 12.4–10.5, producing superoxide ( - O 2 •) and hydroperoxyl (HOO•) radicals.}, number={6}, journal={HOLZFORSCHUNG}, author={Wang, R and Chen, CL and Gratzl, JS}, year={2004}, pages={622–630} }
 @article{wang_chen_gratzl_2004, title={Ozonation of pine kraft lignin in alkaline solution. Part 2: Surface active properties of the ozonated kraft lignins}, volume={58}, ISSN={["1437-434X"]}, DOI={10.1515/HF.2004.117}, abstractNote={Abstract The surface tension and interfacial tension of the F-1000, F-1800, F-5000 and F-15000 fractions obtained by ultrafiltration of the Oz-25-KL, Oz-30-KL and Oz-40-KL preparations (ozonated kraft lignin, KL, preparations with ozone consumption of 25, 30 and 40% per KL) were determined with the concentration range of 1–30 g l -1 at pH of 6, 9 and 11. The surface tension of these ozonated KL preparations decreased with increasing concentration and pH according to the simplified Gibbs adsorption equation for dilute aqueous solution, ∂γ= - RT Γ∂(ln C). The results were discussed in term of functional group contents and weight average molecular mass (M w ) of the ozonated KL preparations. The surface tension of the ozonated KL preparations decreased with increasing carboxylic acid content and, to some extent, phenolic hydroxyl content, but increased with increasing M w . The synergistic effect of the ozonated KL preparations with a commercial surfactant was then investigated. The oil-water interfacial tension was determined in the ozonated KL preparations in an aqueous solution containing 1.5% Petrostep B-120 R and 1.5% sodium chloride with hexane as oil phase by spinning drop technique. The interfacial tension of the system also decreased with increasing the concentration of ozonated KL preparations in the range of 1–16 g l -1 according to the simplified Gibbs adsorption equation. Thus, the addition of a small amount of ozonated KL preparations to the aqueous solution containing 1.5% Petrostep B-120 R and 1.5% sodium chloride showed a remarkable synergistic effect on reducing the interfacial tension.}, number={6}, journal={HOLZFORSCHUNG}, author={Wang, R and Chen, CL and Gratzl, JS}, year={2004}, pages={631–639} }