CFC/PVDF/GO-Fe3+ membrane electrode and flow-through system improved E-Fenton performance with a low dosage of aqueous iron

In this research, we designed a sandwiched electrode membrane filtration system and examined the flow-through E-Fenton performance. The electrochemically active cathodic membrane (CFC/PVDF/GO-Fe3+) was prepared by modifying a PVDF micro-filtration membrane with carbon fiber cloth, graphene oxide and ferric ion, to support the flow-through E-Fenton process. The Fe content of the prepared CFC/PVDF/GO-Fe3+ membrane was 6.458 μg Fe/cm2 with a membrane thickness of 200 μm and 5% GO doping. An insulating spacer made of polyester filter cloth was placed between CFC/PVDF/GO-Fe3+ membrane cathode and carbon fiber cloth anode to form the sandwiched electrode stack. Flow-through H2O2 electrochemical generation experiment indicated 2-electron ORR was the dominant reaction on CFC cathode at optimum applied voltage of 1.6-1.8 V, H2O2 production increased with the increment of flux in flow-through process, and 0.04 M Na2SO4 was adequate to support to the flow-through electrochemical reaction. E-Fenton reaction happened mainly in the membrane matrix and boundary layer, therefore Fe2+ dosage (0.01 mM and 0.025 mM with different sandwiched electrode stack configuration) was necessary to achieve maximum production of HO which was found to be the dominant ROS. Oxalate oxidation experiments suggested that the CFC/PVDF/GO-Fe3+ membrane had excellent stability in proper pH electrolyte solution and selected configuration of sandwiched electrode stack. Rhodamine B degradation in CMB (completely mixed batch reactor) mode followed pseudo-first-order kinetics, and a regenerative E-Fenton performance was confirmed due to the in-situ regeneration of Fe2+ on membrane cathode. The decolorization rate of 10 mg/L Rhodamine B was ∼75% in CSTR (continue stirred tank reactor) mode. This study highlights the potential of modified the polymeric membranes with GO and carbon fiber cloth as the cathodic electrochemical membrane for effective water treatment.