Hydroxyl radical generation in electro-Fenton process with in situ electro-chemical production of Fenton reagents by gas-diffusion-electrode cathode and sacrificial iron anode

Abstract

Hydroxyl radical (·OH) generation in the electro-Fenton process with in situ electro-chemical production of Fenton reagents, i.e. hydrogen peroxide and ferrous ion, by the gas-diffusion-electrode cathode and sacrificial iron anode was systematically investigated. Effects of solution pH and current density (J) on ·OH generation linked strongly with electro-chemical production of hydrogen peroxide at the gas-diffusion-electrode cathode and corrosive production of ferrous ion at sacrificial iron anode were examined. The optimal pH for ·OH generation in the electro-Fenton process was 3 being optimal for the Fenton reaction. The ·OH generation at pH 3 was enhanced with increasing current density and reached the maximum at J=5.8mAcm−2. Further increase in the current density resulted in the retardation of ·OH generation rate. To quantify the ·OH generation, a novel phenomenological reaction kinetic model was developed. The proposed model could quantitatively clarify the ·OH generation in the electro-Fenton process with in situ electro-chemical production of Fenton reagents.