唑啉草酯在液相中的光化学降解

The Photochemical Degradation of Pinoxaden in Liquid Solution

以氙灯为光源,研究了唑啉草酯在不同条件下的光解特性。结果表明:唑啉草酯在甲醇、乙腈、丙酮和正己烷中的光降解均符合一级反应动力学,光解速率由大到小依次为乙腈、正己烷、甲醇和丙酮,光解半衰期分别为9􀆰76、15􀆰1、31􀆰5和138 h。NH_(4)^(+)和NO_(3)^(-)添加浓度为1 mg·L^(-1)显著提高唑啉草酯在水溶液中的光解速率,光解半衰期最短为3􀆰17 h;随着添加浓度的增加,光敏化效应呈明显减弱趋势;Fe^(3+)和Cu^(2+)对唑啉草酯的光解均存在光淬灭效应,淬灭率最高为16􀆰7%。H_(2)O_(2)和TiO_(2)对水溶液中唑啉草酯光解速率的影响均随着其添加浓度增加而加快。以p-亚硝基-N,N-二甲基苯胺(PNDA)为·OH探针性捕获剂证实H_(2)O_(2)和TiO_(2)均能促进产生·OH从而加快唑啉草酯的光解速率。

The photolytic properties of pinoxaden under different conditions were investigated under the irradiation of a xenon lamp.The results show that the photodegradation of pinoxaden in various organic solvents conformed to the first⁃order kinetics.The photolysis rates descended in the order of acetonitrile,n⁃hexane,methanol and acetone,in which the half⁃lives of pinoxaden in these solvents were 9􀆰76,15􀆰1,31􀆰5 and 138 h,respectively.The addition of NH_(4)^(+)and NO_(3)^(-)at 1 mg·L^(-1) significantly increased the photodegradation rate of pinoxaden in aqueous solution,with the shortest half⁃life of pi⁃noxaden as 3􀆰17 h.The sensitization effect induced by these ions reduced as the concentrations further increased.Both Fe^(3+) and Cu^(2+) had a photoquenching effect on the photodegradation of pinoxaden,with a quenching rate up to 16􀆰7%.The photolysis rates of pinoxaden in water were accelerated with increasing concentrations of H_(2)O_(2) and TiO_(2).PNDA was used as a hydroxyl radical indicator to confirm that H_(2)O_(2) and TiO_(2) both promoted the generation of hydroxyl radicals to acceler⁃ate the photodegradation of pinoxaden.