Thermoactivated persulfate oxidation of pesticide chlorpyrifos in aquatic system: kinetic and mechanistic investigations.
The widespread occurrence of organophosphorus pesticides (OPPs) in the environment poses risks to both ecologic system as well as human health. This study investigated the oxidation kinetics of chlorpyrifos (CP), one of the typical OPPs, by thermoactivated persulfate (PS) oxidation process, and evaluated the influence of key kinetic factors, such as PS concentrations, pH, temperature, bicarbonate, and chloride ions. The reaction pathways and mechanisms were also proposed based on products identification by LC-MS techniques. Our results revealed that increasing initial PS concentration and temperature favored the decomposition of CP, whereas the oxidation efficiency was not affected by pH change ranging from 3 to 11. Bicarbonate was found to play a detrimental role on CP removal rates, while chloride showed no effect. The oxidation pathways including initial oxidation of P=S bond to P=O, dechlorination, dealkylation, and the dechlorination-hydroxylation were proposed, and the detailed underlying mechanisms were also discussed. Molecular orbital (MO) calculations indicated that P=S bond was the most favored oxidation site of the molecule. The toxicity of reaction solution was believed to increase due to the formation of products with P=O structures. This work demonstrates that OPPs can readily react with SO4·-and provides important information for further research on the oxidation of these contaminants.
State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection of the People's Republic of China, Nanjing, 210042, People's Republic of China.|Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, 2 Avenue Albert Einstein, F-69626, Lyon, Villeurbanne, France.
Lei
L
Zhou
State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection of the People's Republic of China, Nanjing, 210042, People's Republic of China. zhangya@nies.org.
Ya
Y
Zhang
State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection of the People's Republic of China, Nanjing, 210042, People's Republic of China.
Rongrong
R
Ying
State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection of the People's Republic of China, Nanjing, 210042, People's Republic of China. nies.sepa@163.com.
Guoqing
G
Wang
State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection of the People's Republic of China, Nanjing, 210042, People's Republic of China.
Tao
T
Long
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China.
Jianhua
J
Li
State Environmental Protection Key Laboratory of Soil Environmental Management and Pollution Control, Nanjing Institute of Environmental Sciences, Ministry of Environmental Protection of the People's Republic of China, Nanjing, 210042, People's Republic of China.
Yusuo
Y
Lin
D004390:Chlorpyrifos / Q000737:chemistry*; D054879:Halogenation; D007700:Kinetics; D010084:Oxidation-Reduction; D010575:Pesticides / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*
D010575:Pesticides; D013431:Sulfates; D014874:Water Pollutants, Chemical; D004390:Chlorpyrifos
Chlorpyrifos; Organophosphorus pesticides; Oxidation; Persulfate; Sulfate radicals