Degradation of the Pesticide Chlorpyrifos in Aqueous Solutions with UV/H₂O₂: Optimization and Effect of Interfering Anions

Abstract

This study investigates the use of an advanced oxidation process (AOP) for removal of the pesticide chlorpyrifos in a recirculated system, especially considering the effects of temperature, hydrogen peroxide dosage, pH, pesticide concentration and added inorganic anions. The results indicate that a temperature of 45 °C gave the best performance using only UV-radiation, while for the UV/H₂O₂-method, the temperature did not affect the process. Variations of the pH for the H₂O_2- and the UV/H₂O₂-methods were investigated, where it was observed that pH values did not influence the efficiency of the UV/H₂O₂-method, but enhanced removal of the pesticide occurred at a pH of 10 for the H₂O₂-method. The optimum dosage for the H₂O_2-method was 1.5 g.L^-1. The effects of the addition of 10 mM of chloride, nitrate, sulfate and bicarbonate anions were found not to be significant.