Photocatalytic degradation of the insecticide acetamiprid on TiO2 catalyst

The work is concerned with the photocatalytic degradation of acetamiprid, a widely used pyridine-based neonicotinoid insecticide, in UV-irradiated aqueous suspensions of O-2/TiO2. The rate of degradation was studied by HPLC/DAD and UV spectrophotometry. It was found that the reaction in the investigated concentration range (0.5-2.0 mg cm(-3)) is of a pseudo-first order. The H-1 NMR analysis indicated that beside acetaldehyde, formic and acetic acid, pyridine-containing intermediates ( e. g. 6-chloronicotinic acid) formed during the process. The HPLC/MS measurements also proved the presence of aromatic degradation intermediates. During the photocatalytic process the pH changed by even three units, from 5 to 2. In contrast to the photocatalytic results in the photolytic experimental conditions, acetamiprid appeared to be stable. To get a deeper insight into the complex photocatalytic process of acetamiprid, the photocatalytic degradation of 6-chloronicotinic acid, the detected pyridine-based degradation product, was also investigated.