烯啶虫胺的水解与光解行为研究

Hydrolysis and photolysis behavior of nitenpyram

通过室内模拟实验研究了烯啶虫胺在不同pH值和温度下的水解动态及其在水和有机溶剂中的光解特性和影响因素。结果表明:烯啶虫胺在酸性和中性条件下不易水解,而在碱性条件下水解较快。烯啶虫胺的水解速率随温度升高而增加,平均温度效应系数为2.34。烯啶虫胺水解反应的活化能和活化焓与温度之间无明显相关性,而活化熵与温度表现出较好的相关性。在不同光源照射下,烯啶虫胺在水溶液中的光解速率有显著的差异,在高压汞灯、自然光和氙灯下的光解半衰期分别为42.3 s、6.9 min和55 min;烯啶虫胺在甲醇中的光解速率大于丙酮中的光解速率;烯啶虫胺的光解速率随初始质量浓度的升高而减慢;pH值对烯啶虫胺的光解影响较小。研究结果为烯啶虫胺的环境风险评价提供了科学依据。

The hydrolysis dynamics of nitenpyram under the different pH value and temperatures,and its photolysis dynamics in water or organic solvents were studied.The results showed that the hydrolytic rate of nitenpyram was slow in the acidic and neuter solution,but fast in basic solution.The hydrolytic rate of nitenpyram increased with the increasing temperature and their average coefficient was 2.34.The activation entropy showed a significantly negative correlation with the temperature,but no obvious correla-tions between the activation energy or activation enthalpy to temperature were observed.The photolytic rate of nitenpyram in water under different light sources was significant different to each other,and the half life under high pressure mercury lamp,sun light and xenon lamp was 42.3 s,6.9 min and 55 min,respectively.The photolytic rate of nitenpyram in methanol is faster than that in acetone.The photolytic rate showed negative correclation with the initial concentration of nitenpyram and was slightly affected by the pH value.The results provided scientific base for the environmental risk assessment of nitenpyram.