Photochemistry of insecticide imidacloprid:direct and sensitized photolysis in aqueous medium

Abstract： The direct and sensitized photodegradations of imidacloprid, 1-(6-chloro-3-pyridinylmethyl)-N-nitro-2-imidazolidinimine. were investigated in aqueous solution and with and without various photo-sensitizers. Results of the study revealed that the intensity of lamp-house and irradiation wavelength had significant effects on the photolysis of imidacloprid. Complete degradation of 20 mg/L imidacloprid in aqueous phase was observed in 40 min under ultraviolet(UV) irradiation system, suggesting the ultraviolet ray played significant role in direct photolysis of imidacloprid. The additions of various photo-sensitizers lead to improve the degradation efficiency of imidacloprid under the irradiation of black light fluorescent lamp. TiO2 was the most efficient in the photo-catalytic degradation of imidacloprid among other photo-sensitizers in used this study. However, addition of acetone inhibited the photolysis of imidacloprid under the irradiation of UV, indicating the occurrence of competition between acetone and imidacloprid for photos. Mineralization of the imidacloprid was examined to clarify the final photochemical degradation products of the insecticide which were CO2, Cl- and NO3- . Complete photo-oxidation of nitrogen to NO3- occurred very slowly via the intermediate formation of NH4+ and NO2- . 作 者： ZHENG Wei    LIU Wei-ping    WEN Yue-zhong    Sang-Jin Lee   作者單位： ZHENG Wei,WEN Yue-zhong(Institute of Environmental Science, Zhejiang University, Hangzhou 310027, China)

LIU Wei-ping(Institute of Environmental Science, Zhejiang University, Hangzhou 310027, China;Department of Environmental Sciences, University of California, Riverside, CA 92521, USA)

Sang-Jin Lee(Louisiana Water Resources Research Institute, Louisiana State University, Baton Rouge, LA 70803, USA) 

期 刊： 環(huán)境科學(xué)學(xué)報(英文版)  ISTICSCI   Journal： JOURNAL OF ENVIRONMENTAL SCIENCES  年，卷(期)： 2004, 16(4)  分類號： X131  Keywords： imidacloprid    photolysis    photo-sensitizers    photo-oxidation    mineralization