阿维菌素在水溶液中的光化学降解

Photochemical Degradation of Avermectin in Aqueous Solution

[目的]研究阿维菌素在不同光源下的光解动力学。[方法]以高压汞灯为光源,研究了不同初始浓度、pH值、共存污染物等因素对阿维菌素光化学降解的影响。[结果]阿维菌素在紫外灯下的光解速率是高压汞灯下的数倍,其半衰期在高压汞灯下为25.6 m in,在紫外灯下仅为4.9 m in。阿维菌素的最大吸收峰在245 nm。在试验的初始浓度范围内,阿维菌素的光解反应符合一级反应动力学规律,阿维菌素的光解速率与其初始浓度呈负相关。pH值为4时,阿维菌素的光解半衰期为29.9 m in,pH值为9时,则缩短到了24.8m in。NO3-、甲基绿、甲基橙、十二烷基磺酸钠对阿维菌素的光解速率均表现出一定的光猝灭作用。添加甲基橙后,阿维菌素的光解半衰期比对照延长了7.4 m in,添加甲基绿后延长了9.3 m in。[结论]该试验初步研究了阿维菌素在水溶液中的光解过程及其影响因素。

[ Objective ] The aim was to research the photolysis kinetics of avermectin under different light sources. [ Method ] With high-pres- sure mercury lamp as light source, the influences of factors including different initial concn., pH and co-existing pollutants on the photochemi- cal degradation of avennectin were researched. [ Result ] The photolytic rate of avermectin under UV lamp was several times of that under high-pressure mercury lamp ; its half-life was 25.6 min under high-pressure mercury lamp and only 4.9 min under UV lamp. The maximum absorption peak of avermectin was at 245 nm. In the experimental range of initial concentration, the photolysis reaction of avermeetin accorded with first order reaction kinetics and its photolytie rate was negatively correlated with its initial concn. When the pH value was 4, the photolytie half-life of avermectin was 29.9 rain ; when the pH value was 9, it was shortened to 24.8 min. NO3 -, methyl green, methyl orange and sodi- um dodecyl sulfonate showed some photoextinction effect on the photolytic rate of avermectin. Compared with CK, the photolytic half-life of avermectin was extended for 7.4 rain after adding methyl orange and it was extended for 9.3 min after adding methyl green. [ Conclusion] The photolysis process of avermeetin in aqueous solution and its influencing factors were researched preliminarily in this experiment.