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 O₂ (F_O2), 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, F_O2 = 0.2 L/min and F_solution = 800 μL/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.