Photocatalytic oxidation of propoxur in aqueous titanium dioxide suspensions

Abstract

The photocatalytic oxidation of propoxur, a nitrogen-containing pesticide, has been investigated using aqueous TiO2 suspensions as catalyst in this study. The operating variables considered in the study were initial pH, temperature, [H2O2] and TiO2 loading. Results showed that 1 g/l of TiO2 was the optimum dosage for oxidizing propoxur in this system. Hydrogen peroxide can increase the oxidation rate with increasing its initial concentration. There was no obvious difference in the rate of propoxur oxidation at the initial pH of 4, 6 and 9, and the final pHs of reaction solutions were around 5.5. However, propoxur degraded slower at initial pH 2, and the pH did not vary during the period of photocatalytic reaction. The photocatalytic oxidation of propoxur using TiO2 suspensions as the photocatalyst was reaction-controlled as indicated by the activation energy.