Huang Qing, Li Fasheng, Wang Minxin, Wang Yu, Gu Qingbao, Wang Qunhui
Department of Soil Pollution Control, Chinese Research Academy of Environmental Sciences, Beijing, PR China.
J Environ Sci Health B. 2006;41(3):253-67. doi: 10.1080/03601230500357132.
Photolysis behavior of a new herbicide propisochlor in water media as well as the effects of light sources, initial concentration of propisochlor, pH value, dissolved oxygen (DO) level, and salinity on the photolysis process was investigated. It was found that the relationship between initial concentration of propisochlor and its photodegradation rate was negatively correlated. The changes in acidity and alkalinity of the reaction medium influenced the photoreaction rate evidently. In the alkaline solution the degradation was accelerated. In the reaction media with different pH values, the photolysis followed the first-order kinetics. The presence of dissolved oxygen may promote the photolysis and there existed an optimum of dissolved oxygen concentrations. Increasing the DO level can weaken the promotion and even have an adverse effect. It was demonstrated that with dissolved oxygen the photodegradation of propisochlor followed the first-order kinetics equation. The addition of salt ions Ca2+ and Mg2+ changed the ionic strength and solvent polarity, resulting in the effect on propisochlor photolysis. The photoproducts were detected by both HPLC and GC-MS methods. It was found that photolysis products varied under different light sources. Conclusions may be reached that in the photodegradation of propisochlor, the benzene ring remained intact under irradiation of both solar light and high-pressure mercury lamp, and the amido link was relatively stable, while dechlorination was liable to take place; moreover, alpha-hydrogen at the substituent of benzene ring was active.
研究了新型除草剂异丙草胺在水介质中的光解行为，以及光源、异丙草胺初始浓度、pH值、溶解氧（DO）水平和盐度对光解过程的影响。结果表明，异丙草胺初始浓度与其光降解速率呈负相关。反应介质酸碱度的变化对光反应速率有明显影响。在碱性溶液中降解加速。在不同pH值的反应介质中，光解遵循一级动力学。溶解氧的存在可能促进光解，且存在溶解氧浓度的最佳值。提高溶解氧水平会削弱促进作用，甚至产生不利影响。结果表明，有溶解氧时异丙草胺的光降解遵循一级动力学方程。Ca2+和Mg2+等盐离子的加入改变了离子强度和溶剂极性，从而对异丙草胺光解产生影响。通过高效液相色谱法（HPLC）和气相色谱-质谱联用法（GC-MS）对光产物进行了检测。结果发现，不同光源下光解产物不同。可以得出结论，在异丙草胺的光降解过程中，在太阳光和高压汞灯照射下苯环保持完整，酰胺键相对稳定，而脱氯容易发生；此外，苯环取代基上的α-氢具有活性。
