Degradation of malathion in the solution of acetyl peroxyborate activated by carbonate: Products, kinetics and mechanism

Xiaojie Chai; Yan Cui; Wencai Xu; Lingce Kong; Yanjun Zuo; Ling Yuan; Wenming Chen

doi:10.1016/j.jhazmat.2020.124808

Degradation of malathion in the solution of acetyl peroxyborate activated by carbonate: Products, kinetics and mechanism

J Hazard Mater. 2021 Apr 5:407:124808. doi: 10.1016/j.jhazmat.2020.124808. Epub 2020 Dec 9.

Authors

Xiaojie Chai¹, Yan Cui², Wencai Xu³, Lingce Kong⁴, Yanjun Zuo⁴, Ling Yuan⁴, Wenming Chen⁴

Affiliations

¹ Research Institute of Chemical Defense, Academy of Military Sciences, Beijing 102205, China.
² Research Institute of Chemical Defense, Academy of Military Sciences, Beijing 102205, China; State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China. Electronic address: tracypiscescy@163.com.
³ Research Institute of Chemical Defense, Academy of Military Sciences, Beijing 102205, China; State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China. Electronic address: yjyxwc@sina.com.
⁴ Research Institute of Chemical Defense, Academy of Military Sciences, Beijing 102205, China; State Key Laboratory of NBC Protection for Civilian, Beijing 102205, China.

PMID: 33338811
DOI: 10.1016/j.jhazmat.2020.124808

Abstract

The degradation process of malathion in the acetyl peroxyborate (APB) solution of different APB/malathion molar ratio and in the carbonate-activated APB (APB/CO₃^2-) solution of different pH was studied by ³¹P NMR technology. In the APB solution, all malathion could be degraded in 47.5 min when the molar ratio of APB/malathion was 60. CO₃^2- could effectively activate APB to degrade all malathion in 10 min at pH of 10 when APB/malathion was 10, which was obviously higher than in APB solution. ¹O₂, •O₂^-, •OH and carbon-centered radicals (RC•) could be produced in the APB/CO₃^2- solution, and the degradation of malathion was mainly affected by RC•. The degradation mechanism of malathion in the APB/CO₃^2- solution was proposed based on the research results of malathion degradation process by ³¹P NMR and active species quenching test, which involves two steps: the first step is the oxidation of malathion to malaoxon by RC•, and the second step is the hydrolysis of malaoxon to dimethyl phosphate via hydroxyl anions nucleophilic addition.

Keywords: (31)P NMR; Acetyl peroxyborate; Carbon-centered radicals; Malathion.