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Degradation of sulfamethoxazole by UV, UV/H2O2 and UV/persulfate (PDS): Formation of oxidation products and effect of bicarbonate.
Water Res. 2017 07 01; 118:196-207.WR

Abstract

The frequent detection of sulfamethoxazole (SMX) in wastewater and surface waters gives rise of concerns about their ecotoxicological effects and potential risks to induce antibacterial resistant genes. UV/hydrogen peroxide (UV/H2O2) and UV/persulfate (UV/PDS) advanced oxidation processes have been demonstrated to be effective for the elimination of SMX, but there is still a need for a deeper understanding of product formations. In this study, we identified and compared the transformation products of SMX in UV, UV/H2O2 and UV/PDS processes. Because of the electrophilic nature of SO4-, the second-order rate constant for the reaction of sulfate radical (SO4-) with the anionic form of SMX was higher than that with the neutral form, while hydroxyl radical (OH) exhibited comparable reactivity to both forms. The direct photolysis of SMX predominately occurred through cleavage of the NS bond, rearrangement of the isoxazole ring, and hydroxylation mechanisms. Hydroxylation was the dominant pathway for the reaction of OH with SMX. SO4- favored attack on NH2 group of SMX to generate a nitro derivative and dimeric products. The presence of bicarbonate in UV/H2O2 inhibited the formation of hydroxylated products, but promoted the formation of the nitro derivative and the dimeric products. In UV/PDS, bicarbonate increased the formation of the nitro derivative and the dimeric products, but decreased the formation of the hydroxylated dimeric products. The different effect of bicarbonate on transformation products in UV/H2O2 vs. UV/PDS suggested that carbonate radical (CO3-) oxidized SMX through the electron transfer mechanism similar to SO4- but with less oxidation capacity. Additionally, SO4- and CO3- exhibited higher reactivity to the oxazole ring than the isoxazole ring of SMX. Ecotoxicity of transformation products was estimated by ECOSAR program based on the quantitative structure-activity relationship analysis as well as by experiments using Vibrio fischeri, and these results indicated that the oxidation of SO4- or CO3- with SMX generated more toxic products than those of OH.

Authors+Show Affiliations

State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China. Electronic address: jiangjinhit@126.com.State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China. Electronic address: majun@hit.edu.cn.State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.Key Laboratory of Green Chemical Engineering and Technology of College of Heilongjiang Province, College of Chemical and Environmental Engineering, Harbin University of Science and Technology, Harbin, Heilongjiang, 150040, China.State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

28431352

Citation

Yang, Yi, et al. "Degradation of Sulfamethoxazole By UV, UV/H2O2 and UV/persulfate (PDS): Formation of Oxidation Products and Effect of Bicarbonate." Water Research, vol. 118, 2017, pp. 196-207.
Yang Y, Lu X, Jiang J, et al. Degradation of sulfamethoxazole by UV, UV/H2O2 and UV/persulfate (PDS): Formation of oxidation products and effect of bicarbonate. Water Res. 2017;118:196-207.
Yang, Y., Lu, X., Jiang, J., Ma, J., Liu, G., Cao, Y., Liu, W., Li, J., Pang, S., Kong, X., & Luo, C. (2017). Degradation of sulfamethoxazole by UV, UV/H2O2 and UV/persulfate (PDS): Formation of oxidation products and effect of bicarbonate. Water Research, 118, 196-207. https://doi.org/10.1016/j.watres.2017.03.054
Yang Y, et al. Degradation of Sulfamethoxazole By UV, UV/H2O2 and UV/persulfate (PDS): Formation of Oxidation Products and Effect of Bicarbonate. Water Res. 2017 07 1;118:196-207. PubMed PMID: 28431352.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Degradation of sulfamethoxazole by UV, UV/H2O2 and UV/persulfate (PDS): Formation of oxidation products and effect of bicarbonate. AU - Yang,Yi, AU - Lu,Xinglin, AU - Jiang,Jin, AU - Ma,Jun, AU - Liu,Guanqi, AU - Cao,Ying, AU - Liu,Weili, AU - Li,Juan, AU - Pang,Suyan, AU - Kong,Xiujuan, AU - Luo,Congwei, Y1 - 2017/03/28/ PY - 2016/09/07/received PY - 2017/03/20/revised PY - 2017/03/25/accepted PY - 2017/4/22/pubmed PY - 2017/10/21/medline PY - 2017/4/22/entrez KW - Carbonate radical KW - Hydroxyl radical KW - Sulfamethoxazole KW - Sulfate radical KW - Transformation products SP - 196 EP - 207 JF - Water research JO - Water Res. VL - 118 N2 - The frequent detection of sulfamethoxazole (SMX) in wastewater and surface waters gives rise of concerns about their ecotoxicological effects and potential risks to induce antibacterial resistant genes. UV/hydrogen peroxide (UV/H2O2) and UV/persulfate (UV/PDS) advanced oxidation processes have been demonstrated to be effective for the elimination of SMX, but there is still a need for a deeper understanding of product formations. In this study, we identified and compared the transformation products of SMX in UV, UV/H2O2 and UV/PDS processes. Because of the electrophilic nature of SO4-, the second-order rate constant for the reaction of sulfate radical (SO4-) with the anionic form of SMX was higher than that with the neutral form, while hydroxyl radical (OH) exhibited comparable reactivity to both forms. The direct photolysis of SMX predominately occurred through cleavage of the NS bond, rearrangement of the isoxazole ring, and hydroxylation mechanisms. Hydroxylation was the dominant pathway for the reaction of OH with SMX. SO4- favored attack on NH2 group of SMX to generate a nitro derivative and dimeric products. The presence of bicarbonate in UV/H2O2 inhibited the formation of hydroxylated products, but promoted the formation of the nitro derivative and the dimeric products. In UV/PDS, bicarbonate increased the formation of the nitro derivative and the dimeric products, but decreased the formation of the hydroxylated dimeric products. The different effect of bicarbonate on transformation products in UV/H2O2 vs. UV/PDS suggested that carbonate radical (CO3-) oxidized SMX through the electron transfer mechanism similar to SO4- but with less oxidation capacity. Additionally, SO4- and CO3- exhibited higher reactivity to the oxazole ring than the isoxazole ring of SMX. Ecotoxicity of transformation products was estimated by ECOSAR program based on the quantitative structure-activity relationship analysis as well as by experiments using Vibrio fischeri, and these results indicated that the oxidation of SO4- or CO3- with SMX generated more toxic products than those of OH. SN - 1879-2448 UR - https://www.unboundmedicine.com/medline/citation/28431352/Degradation_of_sulfamethoxazole_by_UV_UV/H2O2_and_UV/persulfate__PDS_:_Formation_of_oxidation_products_and_effect_of_bicarbonate_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0043-1354(17)30244-0 DB - PRIME DP - Unbound Medicine ER -