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

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 degrees 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 H2O2-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 H2O2-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.