Energy efficiency improvement on in situ generating H2O2 in a double-compartment ceramic membrane flow reactor using cerium oxide modified graphite felt cathode

Electrochemical technology offers the possibility of in situ hydrogen peroxide generation whose productivity greatly depends on the cathode properties and the reactor configuration. Herein, cerium oxide modified graphite felt is prepared and used as cathode. Ceramic membrane is integrated dividing the cell to two compartments and preventing decomposition of cathode-generated H2O2 at the anode. H2O2 is found almost impermeable through the membrane as concentration difference < 0.5 M. The double-cell reactor performs higher energy efficiency than the conventional electrolytic cell. And H2O2 accumulation rate has been enhanced in the double-cell in comparison with the undivided one, no matter using either bared or modified cathode. Operation parameters including flow rate of O-2 (FO2), flow rate of electrolyte solution (F-solution), applied current (I) and pH were optimized. Accumulated concentration of H2O2 on the modified cathode reached 260.7 mg/L with the current efficiency up to 75.7% (working conditions C-Na2SO4 = 0.05 M, pH= 2, I = 50 mA, FO2 = 0.2 L/min and F-solution = 800 mu L/min). The yield was 3.8 times higher than using the unmodified cathode. Energy consumption was reduced to 4.8 kWh/kg in the double-cell system (22.1 kWh/kg in the single-cell). In a conclusion, the double-compartment flow reactor is an improved configuration for energy effectiveness and increased productivity of H2O2 for E-Fenton process.