Removal of simazine in a UV/TiO2 heterogeneous system

The degradation of simazine by photocatalytic oxidation in a TiO2 suspension was studied. The influence of various parameters such as wavelength sources, light intensity, TiO2 dosage, and initial pH has been investigated, and the optimum conditions for the degradation of simazine have been identified. The photocatalytic degradation of simazine was observed to follow a pseudo-first-order reaction. The overdose of light intensity and photocatalyst does not always guarantee a beneficial effect on the photocatalytic reaction, and the optimum TiO2 dosage was found to be 0.1 g/L in this study. The optimum pH value is 9.0 for the photocatalytic degradation of simazine, whereas extremely acidic and alkaline conditions inhibit photocatalytic efficiency. Simazine can be fully destroyed, but ring-opening and mineralization are not observed in this system. In addition, seven simazine derivatives (CEAT, OEET, CAAT, ODET, OEAT, OAAT, OOOT) were detected by LC-ESI/MS. It is suggested that dealkylation is the major pathway of simazine photodecay in UV/TiO2 systems. The final product was found to be cyanuric acid.