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 o2/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 1h 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.