Optimizing cathode catalysts using chitosan-coupled nZVI-biochar/conducting carbon black to degrade isopropanol in bioelectro-Fenton systems

Bioelectro-Fenton (BEF) utilizes microorganisms to generate electrons at the anode and transfer them to the cathode via an external circuit to generate hydrogen peroxide (H2O2) and drive the Fenton reaction to produce OH•. Response surface methodology was used to optimize the ratio of nano zero-valent iron-containing biochar and conductive carbon black (nZVI-biochar/CCB) with the chitosan-coated on the surface of the cathode material to promote H2O2 production and reduce the internal resistance of the BEF system. The BEF system using the optimized cathode catalysts showed a 2.6-fold increase in power density and a 2.03-fold increase in open-circuit voltage over the BEF reaction using graphite felt cathodes only. This finding demonstrated that the optimized cathode improved the capability of the cathode to receive electrons. The BEF system with the optimized cathodic catalyst completely removed 400 mg/L isopropanol within 24 h, and the treated wastewater was almost nonbiotoxic.