UV-induced activation of organic chloramine: Radicals generation, transformation pathway and DBP formation

Yangtao Wu; Weiqiu Zhang; Lingjun Bu; Shumin Zhu; Jue Wang; Shiqing Zhou

doi:10.1016/j.jhazmat.2021.126459

UV-induced activation of organic chloramine: Radicals generation, transformation pathway and DBP formation

J Hazard Mater. 2022 Jan 5:421:126459. doi: 10.1016/j.jhazmat.2021.126459. Epub 2021 Jul 28.

Authors

Yangtao Wu¹, Weiqiu Zhang², Lingjun Bu¹, Shumin Zhu³, Jue Wang¹, Shiqing Zhou¹

Affiliations

¹ Key Laboratory of Building Safety and Energy Efficiency, Ministry of Education, Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha 410082, China.
² School of Civil and Environmental Engineering and the Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology, Atlanta, GA 30332, United States.
³ Key Laboratory of Building Safety and Energy Efficiency, Ministry of Education, Department of Water Engineering and Science, College of Civil Engineering, Hunan University, Changsha 410082, China. Electronic address: zshuminwater@163.com.

PMID: 34365233
DOI: 10.1016/j.jhazmat.2021.126459

Abstract

Organic chloramines of little disinfection efficacy commonly exist in disinfection process (chlor(am)ination) due to the wide presence of organic amines in water, of which N-chlorodimethylamine (CDMA) is a typical one. For the first time, UV photolysis for the activation of CDMA was investigated. UV photolysis caused the cleavage of N-Cl bond in CDMA to form Cl^• and subsequently HO^•, both of which are dominant contributors to the destruction of model contaminant bisphenol A (BPA). Typical spectra of HO^• were detected by electron paramagnetic resonance (EPR) experiments, while spectra of reactive nitrogen species (RNS) were not detected during UV photolysis of CDMA. The increase of pH (6.0-8.0), HCO₃^-/CO₃^2-, Cl^- and nature organic matter inhibited the degradation of BPA. We proposed pathways of CDMA and BPA degradation based on the identified transformation products. UV photolysis of CDMA and BPA reduced the formation of N-nitrosodimethylamine (NDMA) at pH 8.0, but increased the formation of trichloronitromethane (TCNM) at pH 7.0 and 8.0. The increasing toxicity and the formation of TCNM and NDMA gave us a hint that formation of organic chloramines should be concerned.

Keywords: Hydroxyl radical; N-Nitrosodimethylamine (NDMA); Organic chloramine; Trichloronitromethane (TCNM); Ultraviolet.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Chloramines*
Disinfection
Photolysis
Ultraviolet Rays
Water Purification*

Substances

Chloramines