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

Abstract

The degradation of chlorpyrifos in water by Fenton (H 2 O 2 /Fe 2+) and solar photo-Fenton (H 2 O 2 /Fe 2+ /solar light) processes was investigated. A laboratory-scale reactor was designed to evaluate and select the optimal oxidation condition. The degradation rate is strongly dependent on pH, temperature, H 2 O 2 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, H 2 O 2 dosing rate 120 mg·min -1, [Fe 2+ ]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 H 2 O 2.