Faculty of Sciences, Department of Chemistry, Biochemistry and Environmental Protection, Trg D. Obradovića 3, 21000 Novi Sad, Serbia.
Chemosphere. 2010 Sep;81(1):114-9. doi: 10.1016/j.chemosphere.2010.07.016. Epub 2010 Aug 6.
Although some studies concerning flash photolysis and photocatalytic ozonation of thiacloprid have already been published, no complete investigation and explanation of the effects of thiacloprid photodegradation under the conditions of UV and UV/H(2)O(2) (high-pressure mercury lamp and H(2)O(2)) have been reported yet. The photochemical degradation of thiacloprid (0.32 mM) was studied under a variety of solution conditions, by varying the initial concentrations of H(2)O(2) from 0 to 162 mM and the pH from 2.8 to 9. In the UV/H(2)O(2) system, thiacloprid reacted rapidly, the maximum first-order rate constant (2.7 x 10(-2)min(-1), r=0.9996) being observed at the H(2)O(2)/thiacloprid molar ratio of 220 and pH 2.8. Under these conditions, 97% of the thiacloprid was removed in about 120 min. The thiacloprid degradation is accompanied by the formation of a number of ionic byproducts (Cl(-), acetate, formate, SO(4)(2-), and NH(4)(+)) and organic intermediates, so that after 35 h of irradiation, 17% of organic carbon remained non-degraded. The application of UV radiation, or H(2)O(2) alone, yielded no significant thiacloprid degradation. The study of the rate of removal of thiacloprid from natural water showed that it is dominantly influenced by the presence of HCO(3)(-).
尽管已经有一些关于噻虫啉的闪光光解和光催化臭氧化的研究，但迄今为止，还没有报道关于在 UV 和 UV/H2O2（高压汞灯和 H2O2）条件下噻虫啉光降解的完整研究和解释。在各种溶液条件下研究了噻虫啉（0.32mM）的光化学降解，通过改变初始 H2O2浓度（从 0 到 162mM）和 pH 值（从 2.8 到 9）来实现。在 UV/H2O2体系中，噻虫啉反应迅速，在 H2O2/噻虫啉摩尔比为 220 和 pH 值为 2.8 时，观察到最大的一级速率常数（2.7x10-2min-1，r=0.9996）。在这些条件下，大约 120 分钟后，97%的噻虫啉被去除。噻虫啉的降解伴随着一些离子副产物（Cl-、醋酸盐、甲酸盐、SO42-和 NH4+）和有机中间体的形成，因此，在照射 35 小时后，仍有 17%的有机碳未被降解。单独应用 UV 辐射或 H2O2都不会导致噻虫啉的显著降解。从天然水中去除噻虫啉的速率研究表明，它主要受 HCO3-的存在影响。
