Cost-effective electro-Fenton using modified graphite felt that dramatically enhanced on H 2 O 2 electro-generation without external aeration

A simple method using carbon black and polytetrafluoroethylene (PTFE) was firstly developed to modify graphite felt which was widely employed as cathode for electro-Fenton, improving the in situ production of H2O2 by about 10.7 times at the optimum carbon black to PTFE mass ratio of 1:5. It was observed that after cathode modification the effect of operating parameters on H2O2 electro-generation, such as O2 flow rate, current density and initial pH, were absolutely different with that before modification, demonstrating a more stable performance over a wider pH and oxygen flow rate ranges. The maximum accumulation of H2O2, up to 472.9 mg/L, was obtained at 50 A/m2 without aeration at initial pH 7, and the H2O2 production capacity remained over 90% after 10-times reuses. The complete removal of 50 mg/L methyl orange by electro-Fenton on the modified cathode was achieved within 15 min, while the total organic carbon removal efficiency reached 95.7% at 2 h, which was more than four-times that on the unmodified one (23.3%). Such a cathode modification accomplishes an efficient and greatly enhanced H2O2 production without external aeration, offering a cost-effective degradation of organic pollutants by electro-Fenton.