Production of Hydrogen Peroxide in Acidic Solutions by Electrodialysis of Peroxide Ions Generated by Electroreduction of Oxygen in Alkaline Solutions

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The on-site generation of hydrogen peroxide in acidic solutions, useful for Fenton oxidation of organic compounds in waste water, was undertaken using an electrolyzer consisting of three compartments separated by an anion-exchange membrane and a cation-exchange membrane. The peroxide ion was produced by electroreduction of oxygen in the catholyte compartment of alkaline solutions and transferred across the anion-exchange membrane to the center compartment of sulfate solutions by electrodialysis. The profile of electrical potential in the electrolyzer was monitored by Pt probes inserted in compartments. The cathode was graphite felt in which oxygen was sparged, and the anode was a DSE plate. The current efficiency was found to become relatively higher by use of electrodialysis of the peroxide ion. The terminal voltage increased with increasing amount of electricity because the resistivity of the anion-exchange membrane increased with increasing transport number of peroxide ion. The concentration of hydrogen peroxide obtained in the center compartment reached 7.5% at 105 coulombs under the most suitable conditions of 4 A, 0.86 kmol·m–3 KOH catholyte and 1 kmol·m–3 H2SO4 center electrolyte.