Electrochemical degradation of m-cresol using porous carbon-nanotube-containing cathode and Ti/SnO2–Sb2O5–IrO2 anode: Kinetics, byproducts and biodegradability

Abstract

The degradation of m-cresol solution was studied using an electrochemical oxidation system with Ti/SnO2–Sb2O5–IrO2 anode for anodic oxidation and porous carbon-nanotube-containing cathode for H2O2 electrogeneration along with Fe3+ reduction. Organic pollutants were oxidized by hydroxyl radical (OH) formed simultaneously in the medium from electro-Fenton reaction in the presence of Fe2+ and at the anode surface from water oxidation. The porous cathode made of graphite, carbon nanotube (CNT) and polytetrafluoroethene (PTFE) exhibited a higher catalytic activity toward O2 reduction producing H2O2 and Fe3+ reduction for Fe2+ regeneration, favoring organics degradation by electro-Fenton oxidation. The degradation kinetics results revealed that the reaction of m-cresol cleavage with hydroxyl radicals could be described by pseudo first-order kinetics. The progress of organics mineralization demonstrated some byproducts were formed during m-cresol degradation. Based on the byproducts identified by GC–MS and HPLC, the sequential process of m-cresol degradation was proposed. Furthermore, the aerobic biological treatment showed that the electrochemical treatment was able to evidently enhance the biodegradability of m-cresol solution.