Electro-Fenton catalyzed with magnetic chitosan beads for the removal of Chlordimeform insecticide

Abstract

The degradation of chlordimeform (CDM) has been investigated by a heterogeneous electro-Fenton process involving magnetite supported chitosan beads (Fe3O4-Cs) as catalyst. The catalyst was prepared by dropwise addition of an acidic chitosan-metal salts solution into sodium hydroxide precipitation bath. SEM, XRD and FTIR analysis were used to characterize the catalysts. The effect of experimental parameters, such as the current intensity, the amount of iron on chitosan beads, the concentration of the catalyst and the initial pH on the pollutant removal rate was investigated. The optimal conditions for the degradation of 37.5 mg L−1 initial CDM concentration were achieved at an applied cathodic current of −5 mA, using 0.5 g L−1 of magnetic chitosan beads (with an average iron amount of 0.104 mmol) and at pH = 3. Under these conditions, CDM was effectively removed within 30 min with 80% of NPOC removal after 6 h of treatment. The reaction followed a pseudo-first order kinetic equation. The adsorption test on the chitosan beads (with and without iron) demonstrated that the insecticide removal was solely induced by heterogeneous electro-Fenton treatment with Fe3O4-CS beads. In addition, the reusability of this catalyst was effectively demonstrated. Finally, LC–MS analysis allowed the proposal of a plausible degradation route.