Production of Hydrogen Peroxide for Drinking Water Treatment in a Proton Exchange Membrane Electrolyzer at Near-Neutral pH

Abstract

We provide a detailed report on the electrosynthesis of H 2 O 2 for drinking water treatment under near-neutral conditions using a proton exchange membrane (PEM) electrolyzer. Two novel cathode catalysts for O 2 electroreduction to H 2 O 2 were investigated in the PEM electrolyzer: an inorganic cobalt-carbon (Co–C) composite and an organic redox catalyst anthraquinone-riboflavinyl mixed with carbon (AQ–C), respectively. The impact of operational variables such as temperature, cathode carrier water flow rate, and anode configurations (aimed at mitigating carbon corrosion at the anode) were examined in single-pass and full recycle operation. Using a superficial current density of 245 mA cm −2 and an operating temperature of 40 °C, H 2 O 2 molar fluxes of 360 μ mol hr −1 cm −2 and 580 μ mol hr −1 cm −2 were generated at near-neutral pH with the Co–C and RF-AQ catalysts, respectively. Seventy-two hour experiments with closed loop recirculation, produced H 2 O 2 concentrations of 1300 and 3000 ppm for the Co–C and AQ–C catalysts, respectively. These concentrations are adequate for advanced oxidation (UV/H 2 O 2 ) treatment of drinking water, rendering the PEM electrolysis approach particularly suitable for on-site and on-demand production of H 2 O 2 .