The capability of producing hydrogen peroxide via cathodic oxygen reduction has opened up several opportunities for the use of such electrochemical cells in water and wastewater treatment. Some well-studied examples include electro-Fenton oxidation of aromatic compounds, dyes and other trace organics, and disinfection, among others. Cathodic peroxide production is especially attractive as it is possible to produce peroxide at fairly positive cathode potentials, resulting in low energy input. Peroxide could also be produced in microbial fuel cells, wherein it is even possible to do so without any theoretical energy input. Over the past few years, we have studied several aspects of cathodic peroxide production in electrochemical cells, in order to improve production rates and efficiencies, while lowering cathodic voltage losses. These include the effect of catalyst material, thickness, electrolyte composition and pH, cathodic hydaulic retention time (HRT), reactor materials, presence of peroxide stabilizing agents, and air flow rate past the cathodic gas diffusion layer. In this presentation, we will summarize the key results from these studies. Most notably: we have found that carbon black catalyst over carbon cloth gas diffusion layer results in low cathodic overpotentials, while steering the oxygen reduction reaction to peroxide production. The thickness of the catalyst layer plays a key role in the efficiency of peroxide production, as thicker catalysts (and thus larger catalyst loadings) result in complete reduction of oxygen to water. Electrolyte composition has a major effect on the stability of peroxide produce - with low compatability with carbonate. Our results pave the way for further development of electrochemical cells that produce peroxide. In this presentation, we will also share results from bench-scale testing of one possible application of electrochemcial cells that produce peroxide:  in landfill leachate treatment.

Factors that affect cathodic hydrogen peroxide production for water and wastewater treatment applications

254th National Meeting (2017)

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