Hydrogen peroxide production in a pilot-scale microbial electrolysis cell.

Area of Science:

• Electrochemistry
• Environmental Biotechnology
• Sustainable Chemistry

Background:

• Microbial electrolysis cells (MECs) offer a sustainable platform for bioelectrochemical processes.
• Hydrogen peroxide (H2O2) is a valuable oxidant with diverse applications.
• Optimizing H2O2 production in MECs requires understanding factors like cathodic pH and membrane type.

Purpose of the Study:

• To evaluate the feasibility of H2O2 production in a pilot-scale dual-chamber MEC.
• To investigate the impact of cathodic pH, controlled by different membranes, on H2O2 yield.
• To determine the efficiency of H2O2 conversion in the MEC system.

Main Methods:

• A pilot-scale dual-chamber MEC with a carbon gas-diffusion cathode was operated using acetate as the electron donor.
• The MEC was tested with both an anion exchange membrane (AEM) and a cation exchange membrane (CEM) to vary cathodic pH.
• Current density and H2O2 conversion efficiency were measured under applied voltages.

Main Results:

• Maximum current densities of 0.94-0.96 A/m2 were achieved, irrespective of the membrane used.
• The highest H2O2 conversion efficiency recorded was 7.2 ± 0.09% with the cation exchange membrane (CEM).
• Low conversion efficiency was attributed to H2O2 reduction or decomposition within the cathode or bulk liquid.

Conclusions:

• Large-scale MECs are not suitable for concentrated H2O2 production due to low conversion efficiency.
• MECs show potential for sustainable in-situ oxidation processes, particularly in wastewater treatment applications.
• Further research is needed to mitigate H2O2 loss mechanisms in MEC systems.