碘甲磺隆钠盐在水溶液中的光解研究

为了解碘甲磺隆钠盐在水溶液中的光降解特性,评价其环境安全性,以太阳光和高压汞灯为光源,进行光解试验,研究了碘甲磺隆钠盐在不同水溶液中的光解行为及水体pH值对其光解的影响。结果表明,碘甲磺隆钠盐在所有试验水体中的降解均符合一级动力学方程,不同水体中碘甲磺隆钠盐的半衰期分别为14.29～21.26h（太阳光）与2.29～3.76min（高压汞灯）,两种光源下碘甲磺隆钠盐在各自然水体中的降解速率依次为井水〉河水〉池塘水〉稻田水。不同pH值水体中的光解实验表明,碘甲磺隆钠盐在酸性介质中的光解比在碱性介质中快,顺序为pH5〉pH7〉pH9〉pH11。

Photodegradation of Iodosulfuron-methyl-sodium in Aqueous Solution

The photodegradation of iodosulfuron-methyl-sodium（IMS）,a sulfonylurea herbicide,had been investigated in different types of natural water（ground,pond,river,paddy） and distilled water while the influence of the initial concentration of IMS and the dissolved oxygen in water on the kinetics were evaluated. Degradation kinetics was monitored under natural sunlight and simulated solar irradiation（high-pressure mercury lamp light）.The rates of photodegradation of the studied herbicide in different natural water follows first-order kinetics with half-lives ranging from 14.29 to 21.26 h（natural sunlight） and from 2.29 to 3.76 min（simulated solar irradiation）. The rate constants of degradation in different types of water followed the order：ground water river waterpond water paddy water. The differences in rates of photodegradation were dependent upon the water texture and organic matter content. The experiment had shown that the degradation rate was reduced with the increasing of the initial concentration of IMS under sunlight. On the contrary,it was found that the degradation rate is accelerated as the initial concentration of IMS in solution increases under simulated solar irradiation. Photodegradation of IMS in phosphate buffer was conducted in buffer solution of different pH value and the results showed that the photolysis rate was quicker in pH5 than that was in other buffers and the photolysis rate was in the order of pH5〉pH7〉pH9〉pH11. The study had shown that the IMS was very readily to be decreased under simulated solar irradiation.