Decomposition of monocrotophos in aqueous solution by UV irradiation in the presence of titanium dioxide

The decomposition of monocrotophos in aqueous solution by UV/TiO2 reduction process was studied under various pH values, TiO2 dosages, light intensities, dissolved oxygen levels and other operating conditions. The presence of dissolved oxygen inhibits the recombination of electrons and holes, and enhance the decomposition of monocrotophos by UV/TiO2 process, but excessive dissolved oxygen posed no further effect on the decomposition of monocrotophos. The decomposition rates of monocrotophos were significantly higher for acidic solutions than those for alkaline solutions. Increasing the light intensity would drastically increase the decomposition rate of monocrotophos, but was ultimately influenced by the amount of TiO2 present in solutions. The quasi-global kinetics based on a simplified consecutive reaction scheme was developed to describe the temporal behavior of monocrotophos decomposition in aqueous solution by UV/TiO2 process.