Insights into generation mechanisms of halogen radicals from excited triplet state of dissolved organic matter

Wenjie Jin; Fangyuan Cheng; Yue Liu; Hao Yang; Yangjian Zhou; Jiao Qu; Ya-Nan Zhang

doi:10.1016/j.scitotenv.2022.155280

Insights into generation mechanisms of halogen radicals from excited triplet state of dissolved organic matter

Sci Total Environ. 2022 Aug 15:834:155280. doi: 10.1016/j.scitotenv.2022.155280. Epub 2022 Apr 13.

Authors

Wenjie Jin¹, Fangyuan Cheng¹, Yue Liu¹, Hao Yang¹, Yangjian Zhou¹, Jiao Qu¹, Ya-Nan Zhang²

Affiliations

¹ State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun, Jilin 130117, China.
² State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun, Jilin 130117, China. Electronic address: zhangyn912@nenu.edu.cn.

PMID: 35427609
DOI: 10.1016/j.scitotenv.2022.155280

Abstract

Triplet states of dissolved organic matter (³DOM*) can sensitize the generation of halogen radicals in marine water. The generation pathways of halogen radicals from ³DOM* is still not fully understood. In this study, the generation of halogen radicals from DOM was investigated with Suwanee River fulvic acid (SRFA) as a representative and detailed generation pathways were further revealed with anthraquinone-2-sodium sulfonate (AQ2S) as a triplet sensitizer. The results showed that in SRFA solutions with halogen ions, various halogen radicals can be generated. Among which, Br is formed by the reaction of Br^- with ³AQ2S*, and Cl is produced by the reaction of Cl^- with AQ2S⁺ that generated in the presence of dissolved oxygen (DO). Cl₂^- and Br₂^- were generated via the subsequent combination of Cl/Br with another Cl^-/Br^-. In solutions without DO, BrCl^- is mainly generated through the combination of Br with Cl^-, and BrCl^- could also be generated through the combination of Cl with Br^- in solutions with DO. This study provides deep insights into the generation mechanisms of different halogen radicals from ³DOM* and is helpful for understanding the photochemical processes of halogen radicals in marine waters.

Keywords: Anthraquinone-2-sodium sulfonate; Environmental photochemistry; Halogen radical; Suwanee River fulvic acid.

MeSH terms

Dissolved Organic Matter
Halogens*
Photolysis
Rivers
Water Pollutants, Chemical*

Substances

Dissolved Organic Matter
Halogens
Water Pollutants, Chemical