百菌清与丙溴磷混合水溶液的光化学降解

Photodegradation of the mixture of chlorothalonil and profenofos

为明确水体中百菌清和丙溴磷的混合光降解行为,利用模拟光源(高压汞灯)研究了百菌清和丙溴磷混合水溶液中的光降解作用和光降解产物。结果表明:在高压汞灯照射下,浓度为3μmol/L的百菌清光降解的半衰期为122.46 min,浓度为3、6和9μmol/L的丙溴磷光解半衰期分别为87.85、86.11和87.63 min。在3μmol/L的百菌清水溶液中分别添加1、2和3倍(3、6和9μmol/L)的丙溴磷后,百菌清的光降解半衰期分别降至64.54、38.25和33.05 min,光降解速率分别提高了1.90、3.20和3.71倍;而丙溴磷的光降解半衰期分别为85.57、83.51和84.32 min,降解速率均未发生显著变化。表明丙溴磷对百菌清在纯水中的光降解具有明显的促进效应,且降解速率与丙溴磷浓度呈正相关,而百菌清则对丙溴磷的光降解无影响。百菌清水溶液在单独光降解和加入丙溴磷后,其光降解产物均为4-羟基百菌清;而丙溴磷则产生了5种光降解产物,分别为4-溴-2氯苯基磷酸氢乙酯、O-(4-溴-2-氯苯基)-O-乙基-S-氢磷酸、O-(2-氯苯基)-O-乙基-S-丙基硫代磷酸酯、(2-氯-4-羟基苯基)邻乙基-S-丙基硫代磷酸酯和2-氯-4-溴苯酚。百菌清和丙溴磷的混合水溶液在光照下产生了更多的羟基自由基。该研究可为评估百菌清和丙溴磷复合污染对环境的生态毒性提供重要理论支撑。

The photodegradation behavior of the mixture of chlorothalonil and profenofos in water was investigated under high pressure mercury lamp(HPML).The results showed that the half-life of chlorothalonil at 3μmol/L was 122.46 min under the HPML irradiation,and the half-lives of chlorothalonil were 64.54,38.25 and 33.05 min in the presence of 1,2 and 3 equivalent of profenofos.The half-lives of 3,6,and 9μmol/L profenofos were 87.85,86.11 and 87.63 min,while they were 85.57,83.51 and 84.32 min in the presence of chlorothalonil,respectively.This indicates that profenofos promoted the photodegradation of chlorothalonil in water and the promotion effect was increased as the concentration of profenofos increased.Chlorothalonil did not affect the photodegradation of profenofos.The main photodegradation product of chlorothalonil was 4-hydroxyl chlorothalonil with and without profennofos.Five photodegradation products of profenofos were detected,namely,4-bromo-2-chlorophenyl hydrogen phosphate ethyl ester,O-(4-bromo-2-chlorophenyl)-O-ethyl-S-hydrogen phosphate,O-(2-chlorophenyl)-O-ethyl-S-propyl phosphorothioate,(2-chloro-4-hydroxyphenyl)-O-ethyl-S-propyl phosphorothioate,and 2-chloro-4-bromophenol.Profenofos promoted the degradation of chlotothalonil via the generation of more hydroxyl radicals.This study provides important theoretical support for the evaluation of the environmental ecotoxicity of combined pollution of chlorothalonil and profenofos.