Abdelhédi Fenton and solar photo-Fenton processes for the removal of chlorpyrifos insecticide in wastewater

The degradation of chlorpyrifos in water by Fenton (H2O2/Fe 2+) and solar photo-Fenton (H2O2/Fe 2+/solar light) processes was investigated. A laboratory-scale reactor was designed to evaluate and select the optimal oxidation condition. The degrada-tion rate is strongly dependent on pH, temperature, H2O2 dosing rate, and initial concentrations of the insecticide and Fe 2+. The kinetics of organic matter decay was evaluated by means of chemical oxygen demand (COD) measurement. Overall kinetics can be described by a pseudo-second-order rate equation with respect to COD. The optimum conditions were obtained at pH 3, H2O2 dosing rate 120 mg∙min –1, [Fe2+]0 5.0 mM, initial COD 1 330 mg∙ℓ –1 and 35°C for the Fenton process. However, in the solar photo-Fenton process, the degradation rate increased significantly. To achieve 90 % of COD removal, the solar photo-Fenton process needs 50 % less time than that used in the Fenton process which translates to a 50 % gain of H2O2