Photocatalytic degradation of imidacloprid in aqueous suspension of TiO₂ supported on H-ZSM-5

The composite of TiO₂ and zeolite H-ZSM-5 has great photocatalytic ability for organic contaminants over a very large specific surface area and highlighted adsorption capacity. To describe abiotic degradation of imidacloprid, the photoinduced degradation of the pesticide imidacloprid in aqueous solutions, in the presence of TiO₂ supported on H-ZSM-5 as photocatalyst, was performed. The study focused on the comparison of the imidacloprid degradation between photolysis and photocatalysis. The experimental results showed that the degradation of imidacloprid was more rapid in the condition of photocatalytic than that of photolysis or TiO₂-only. The identification of possible intermediate products during the degradation was investigated by the high-performance liquid chromatography coupled with electrospray time-of-flight mass spectrometry (HPLC/TOF-MS). The main photocatalytic products were identified as chloronictinic acid, 1-[(6-chloro-3-pyridinyl) methyl]-2-imidazolidinone and 1-[(6-chloro-3-pyridinyl) methyl]-N-nitroso-2-imidazolidimine.