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The multiple roles of chlorite on the concentrations of radicals and ozone and formation of chlorate during UV photolysis of free chlorine.
Water Res. 2021 Feb 15; 190:116680.WR

Abstract

Chlorine dioxide (ClO2) has emerged as a promising alternative to free chlorine for water disinfection and/or pre-oxidation due to its reduced yields of chlorinated disinfection byproducts. ClO2 decomposes to form chlorite (ClO2-), which influences the following advanced oxidation processes (AOPs) for micropollutant abatement in drinking water. This study aims at investigating the effects of ClO2- on the concentrations of reactive species (e.g., radicals and ozone) and on the formation of chlorate in the UV/chlorine AOP. Results showed that the concentration of ClO· in the UV/chlorine process remarkably decreased by 98.20-100.00% in the presence of ClO2- at concentration of 0.1-1.0 mg·L-1 as NaClO2. The concentrations of HO· and ozone decreased by 42.71-65.42% and by 22.02-64.31%, respectively, while the concentration of Cl· was less affected (i.e., 31.00-36.21% reduction). The overall concentrations of the reactive species were differentially impacted by ClO2-'s multiple roles in the process. UV photolysis of ClO2- generated HO· but not Cl·, ClO· or ozone under the drinking water relevant conditions. ClO2- also competed with chlorine for UV photons but this effect was minor (< 1.0%). The radicals/ozone scavenging by ClO2- outcompeted the above two to lead to the overall decreasing concentrations of the reactive species, in consistency with the kinetic model predicted trends. ClO2- reacted with radicals and ozone to form chlorate (ClO3-) but not perchlorate (ClO4-). HO· played a dominant role in ClO3- formation. The findings improved the fundamental understanding on micropollutant abatement and inorganic byproduct formation by the UV/chlorine process and other AOPs in ClO2--containing water.

Authors+Show Affiliations

Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong; Hong Kong Branch of Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275, China.School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Sun Yat-sen University, Guangzhou, 510275, China. Electronic address: yangx36@mail.sysu.edu.cn.Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong. Electronic address: ryin@connect.ust.hk.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

33285457

Citation

Zhao, Jing, et al. "The Multiple Roles of Chlorite On the Concentrations of Radicals and Ozone and Formation of Chlorate During UV Photolysis of Free Chlorine." Water Research, vol. 190, 2021, p. 116680.
Zhao J, Shang C, Zhang X, et al. The multiple roles of chlorite on the concentrations of radicals and ozone and formation of chlorate during UV photolysis of free chlorine. Water Res. 2021;190:116680.
Zhao, J., Shang, C., Zhang, X., Yang, X., & Yin, R. (2021). The multiple roles of chlorite on the concentrations of radicals and ozone and formation of chlorate during UV photolysis of free chlorine. Water Research, 190, 116680. https://doi.org/10.1016/j.watres.2020.116680
Zhao J, et al. The Multiple Roles of Chlorite On the Concentrations of Radicals and Ozone and Formation of Chlorate During UV Photolysis of Free Chlorine. Water Res. 2021 Feb 15;190:116680. PubMed PMID: 33285457.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The multiple roles of chlorite on the concentrations of radicals and ozone and formation of chlorate during UV photolysis of free chlorine. AU - Zhao,Jing, AU - Shang,Chii, AU - Zhang,Xinran, AU - Yang,Xin, AU - Yin,Ran, Y1 - 2020/11/27/ PY - 2020/08/26/received PY - 2020/11/08/revised PY - 2020/11/24/accepted PY - 2020/12/8/pubmed PY - 2021/1/29/medline PY - 2020/12/7/entrez KW - Advanced oxidation process (AOP) KW - Chlorate KW - Chlorite KW - Ozone KW - Radicals KW - UV/chlorine SP - 116680 EP - 116680 JF - Water research JO - Water Res VL - 190 N2 - Chlorine dioxide (ClO2) has emerged as a promising alternative to free chlorine for water disinfection and/or pre-oxidation due to its reduced yields of chlorinated disinfection byproducts. ClO2 decomposes to form chlorite (ClO2-), which influences the following advanced oxidation processes (AOPs) for micropollutant abatement in drinking water. This study aims at investigating the effects of ClO2- on the concentrations of reactive species (e.g., radicals and ozone) and on the formation of chlorate in the UV/chlorine AOP. Results showed that the concentration of ClO· in the UV/chlorine process remarkably decreased by 98.20-100.00% in the presence of ClO2- at concentration of 0.1-1.0 mg·L-1 as NaClO2. The concentrations of HO· and ozone decreased by 42.71-65.42% and by 22.02-64.31%, respectively, while the concentration of Cl· was less affected (i.e., 31.00-36.21% reduction). The overall concentrations of the reactive species were differentially impacted by ClO2-'s multiple roles in the process. UV photolysis of ClO2- generated HO· but not Cl·, ClO· or ozone under the drinking water relevant conditions. ClO2- also competed with chlorine for UV photons but this effect was minor (< 1.0%). The radicals/ozone scavenging by ClO2- outcompeted the above two to lead to the overall decreasing concentrations of the reactive species, in consistency with the kinetic model predicted trends. ClO2- reacted with radicals and ozone to form chlorate (ClO3-) but not perchlorate (ClO4-). HO· played a dominant role in ClO3- formation. The findings improved the fundamental understanding on micropollutant abatement and inorganic byproduct formation by the UV/chlorine process and other AOPs in ClO2--containing water. SN - 1879-2448 UR - https://www.unboundmedicine.com/medline/citation/33285457/The_multiple_roles_of_chlorite_on_the_concentrations_of_radicals_and_ozone_and_formation_of_chlorate_during_UV_photolysis_of_free_chlorine_ DB - PRIME DP - Unbound Medicine ER -