On the ability to electrogenerate hydrogen peroxide and to regenerate ferrous ions of three selected carbon-based cathodes for electro-Fenton processes

This paper compares three different carbon-based materials as cathodes in electro-Fenton processes. In particular, we investigated a graphite, a carbon felt (CF) and a reticulated vitreous carbon (RVC) electrode with a focus on both electrogeneration of hydrogen peroxide and reduction of ferric ions. The influence of the operative parameters such as current intensity, pH, temperature and feeding gas was studied by conducting galvanostatic electrolyses in a two-compartment reactor separated by a cationic membrane. The dissolved oxygen concentration was optimized and monitored. The results obtained showed that all the cathodes presented good ability to electrogenerate hydrogen peroxide. Unlike graphite, the tridimensional electrodes exhibited superior performances in air flow and the possibility to adopt higher currents. Interestingly, their behavior differed significantly in the electroregeneration of ferrous ions. In this case, RVC and CF presented efficiencies and reduction rates higher than graphite and resulted almost unaffected by the operative conditions.