Mass transport control of oxygen reduction at graphite felt with subsequent decolourisation of RB-5 dye in a parallel plate flow reactor

Abstract 3D Porous electrodes show excellent performance in industrial electrochemical engineering. Such electrodes perform better than planar electrodes in terms of their greater surface area, higher volumetric porosity, turbulence promotion of electrolyte and reasonable mass transfer rates. This paper considers the mass transfer studies of the oxygen reduction reaction (ORR) during the cathodic generation of H2O2 at carbon felt (CF) electrodes in a divided parallel plate electrochemical flow reactor. The volumetric mass transport coefficient obtained from voltammetric limiting current measurements increased at higher mean linear flow velocities in the rectangular channel of a parallel plate flow reactor. The cathodic compartment of the reactor has an equivalent diameter of 0.96 cm and it is separated from the anodic compartment by a cationic Nafion 115 membrane. A volumetric mass transfer coefficient (kmAe) of 0.74 s−1 was achieved at a mean linear flow velocity of 2.2 cm/s. Optimal conditions for H2O2 generation resulted in 95% Faradaic current efficiency and allowed up to 99% decolourisation of an organic RB-5 dye by electro Fenton oxidation.