TiO2/H2O2 mediated UV photocatalysis of Chlorpyrifos: Optimization of process parameters using response surface methodology

Chlorpyrifos (CP), an organophosphate pesticide which is used extensively in agricultural fields of various developing countries, is found to cause neurological and immunological effects on living beings. In this study, TiO2/H2O2 mediated UV photocatalytic oxidation of CP was investigated in a laboratory-scale photo-reactor. Experiments were designed using three level Box-Behnken factorial design (BBD) technique combined with response surface methodology (RSM). Effects of the process parameters such as concentration of TiO2, concentration of H2O2 and initial pH on the response parameters like degradation of chemical oxygen demand (COD) and degradation of CP were analyzed using polynomial regression models. After 3 h reaction time, with the optimum process parameters, about 68.29% and 74.38% of COD degradation and CP degradation, respectively were achieved. Kinetic and synergistic studies for different oxidation systems viz., H2O2, UV + H2O2, UV + TiO2 and UV + TiO2 + H2O2 were also performed using the optimum conditions. Statistical models developed in this study can be used for optimization of oxidation processes for treatment of industrial as well as agricultural wastewater.