Photocatalytic degradation of selected s-triazine herbicides and organophosphorus insecticides over aqueous TiO2 suspensions

The photocatalytic degradation of selected s-triazine herbicides and organo phosphorus insecticides was carried out in aqueous TiO2 suspensions under s imulated solar light. The tested herbicides from the s-triazines group were atrazine, propazine, cyanazine, prometryne, and irgarol. The tested insect icides from the organophosphorus group were ethyl parathion, methyl parathi on, ethyl bromophos, methyl bromophos, and diclofenthion. Degradation kinet ics followed first-order reaction and has been monitored through gas chroma tography. The degradation was fast with half-lives varying from 10.2 to 38. 3 min depending on the nature and the structure of compounds. The generated transformation products (TPs) were formed via oxidation, dealkylation, and dechlorination for s-triazines and via oxidation and photohydrolysis for o rganophosphates. The TPs of irgarol, bromophos, and dichlofenthion were ide ntified using solid-phase extraction (SDB-disks) and GC-MS techniques, and possible degradation routes were proposed showing similar degradation pathw ays as for other triazines and organophosporus pesticides. This work points out to the necessity of extended knowledge of the successive steps in a so lar-assisted detoxification process.