Photocatalyzed degradation of agrochemicals in TiOz aqueous suspensions

The photocatalyzed degradation of ten agrochemicals (simazine, benthiocarb, thiram, diazinon, fenitrothion, isoprothiolane, propyzamide, dichlorvos, fenobucarb, and iprobenfos) has been investigated in an aqueous suspension of TiOj using a ultra high-pressure mercury lamp ( A ]>290 nm). The degradation is much faster than direct photolysis without TiOi and depends on the structures of the agrochemicals. As for iprobenfos, the effects of light intensity, wavelength, initial concentration, partial pressure of Ojin bubbling gases, reaction temperature, and pH on the degradation rate are examined and a kinetic equation is proposed to explain the experimental results. Several intermediates and probable pathways of the degradation are also proposed.