High removal efficiency of dye pollutants by electron-Fenton process using a graphene based cathode

Abstract

A new cathode for electro-Fenton process was set up by electrochemical deposition of reduced graphene oxide (rGO) on the surface of carbon felt (CF). The structure and properties of modified electrode was investigated. Among the different reduction methods used, the constant potential technique demonstrated significant advantages. The parameters affecting the conversion of GO to rGO, such as pH, applied potential and duration of the reduction process, were investigated. The rGO modified cathode presents enhanced electrochemical properties like an increase of the redox current and a decrease of the charge transfer resistance in presence of the redox probe [Fe(CN)6]3−/[Fe(CN)6]4− showing better kinetic properties compared to raw CF. This improvement enhanced significantly the production of hydrogen peroxide, a key parameter in electro-Fenton (EF) process, which was confirmed by linear scanning voltammetry (LSV) analysis. Therefore, the use of graphene modified cathode could decolorize efficiently Acid Orange 7, a model azo dye molecule, within only 5min and almost completely mineralized (94.3%) it in 8h treatment under optimal current density applied. The new cathode exhibited good stability as the mineralization ratio in 2h that was still above 64% after 10 cycles’ degradation, showing that this rGO-CF is a powerful and promising electrode for improving the removal efficiency of dye pollutants using EF technology.