Electrochemical generation of hydrogen peroxide using carbon black-, carbon nanotube-, and carbon black/carbon nanotube-coated gas-diffusion cathodes: effect of operational parameters and decolorization study

Abstract

The aim of this study was to investigate the efficiency of the carbon black (CB)-polytetrafluoroethylene (PTFE)-, carbon nanotube (CNT)-PTFE-, and CB-CNT-PTFE-coated gas-diffusion cathode (GDC) for the electrochemical generation of H2O2 and its capability for degradation of organic pollutants. Results showed that the CB-CNT-PTFE-coated GDC was the most efficient cathode for the generation of H2O2, but the CB-PTFE-coated GDC can be chosen as an economical coating composite. The amount of H2O2 generated on the uncoated, PAC-PTFE-coated, CNT-PTFE-coated, CB-PTFE-coated, and CB-CNT-PTFE-coated GDC was 21.68, 58.45, 100.9, 112.3, and 123.5 μM, respectively, within a reaction time of 40 min. The effects of pH, current intensity, and electrolyte concentration on the generation of H2O2 were investigated. The electrochemical generation of H2O2 increased with increasing current intensity and electrolyte concentration. According to the results and from the economical point of view, the optimal pH, current intensity, and electrolyte concentration were 7.0, 150 mA, and 0.08 M, respectively. The obtained data showed that the electrochemical process equipped with CB-PTFE-coated GDC would be efficient for treating wastewater containing Acid Red 18 as a model organic pollutant. A decolorization efficiency of 95.35 % was achieved for an initial dye concentration of 10 mg/L at a reaction time of 70 min.