Analyzing disinfection by-products yield and mechanisms in UV/Cl2 using response surface methodology and quantitative structure-activity relationship models

Jingjing Yao; Haipu Li; Say Leong Ong; Jiangyong Hu

doi:10.1016/j.chemosphere.2023.140072

Analyzing disinfection by-products yield and mechanisms in UV/Cl₂ using response surface methodology and quantitative structure-activity relationship models

Chemosphere. 2023 Nov:341:140072. doi: 10.1016/j.chemosphere.2023.140072. Epub 2023 Sep 5.

Authors

Jingjing Yao¹, Haipu Li², Say Leong Ong³, Jiangyong Hu⁴

Affiliations

¹ Department of Civil & Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore; Pillar of Engineering Product Development, Singapore University of Technology and Design, 8 Somapah Road, 487372, Singapore; Center for Environment and Water Resources, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China.
² Center for Environment and Water Resources, College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, PR China; Key Laboratory of Hunan Province for Water Environment and Agriculture Product Safety, Changsha 410083, PR China. Electronic address: lihaipu@csu.edu.cn.
³ Department of Civil & Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore.
⁴ Department of Civil & Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore; NUS Environmental Research Institute, National University of Singapore, 5A Engineering Drive 1, Singapore 117411, Singapore. Electronic address: ceehujy@nus.edu.sg.

PMID: 37678597
DOI: 10.1016/j.chemosphere.2023.140072

Abstract

The study aimed to investigate the formation of halogenated disinfection byproducts (DBPs) during applying UV/chlorine (UV/Cl₂) and unravel the interactive impacts of critical operational parameters and the mechanisms behind DBPs formation. Response surface methodology and quantitative structure-activity relationship models were developed to evaluate the contribution of electrophilic, nucleophilic, and free radical reactions to the formation of DBPs in UV/Cl₂. The study found that Cl₂ and its interactions dominated the total DBPs and non-Br-DBPs formation, while Br^- and the Cl₂-Br^- interaction played a decisive role in the Br-DBPs formation. The study also observed significant interactions of Br, Cl₂, and pH on chloroform, bromodichloromethane, dichloroacetonitrile, 1,1-dichloro-2-propanone, trichloroactic acid, and chlorodibromoacetic acid formations, while no evident interaction on chloral hydrate, dibromochloromethane, trichloroacetone, dibromoacetic acid, and bromodichloroacetic acid formations. The electrophilic substitution of HOBr mainly controlled the formation of trihalomethanes, and the contribution of nucleophilic, electrophilic, and free radical (•OH, Cl•, Cl₂•^- and ClO•) reactions depended on the molar ratio of Cl₂ to Br, and pH-determined hydrolysis rate constants of DBPs and the types of free radicals. Overall, the response surface methodology and quantitative structure-activity relationship models provided a reference for revealing DBPs formation mechanisms in other disinfection processes.

Keywords: Disinfection byproducts; Quantitative structure-activity relationship; Response surface methodology; UV/Chlorine.

MeSH terms

Chloral Hydrate
Chlorides
Chlorine
Disinfection*
Halogens
Quantitative Structure-Activity Relationship*

Substances

Chloral Hydrate
Chlorides
Chlorine
Halogens