Effect of air pressure on the electro-Fenton process at carbon felt electrodes

The effect of air pressure on electro-Fenton (PrEF process) was evaluated using two organic substances (maleic acid and Acid Orange 7) as model organic pollutants. First experiments were performed using a conventional carbon felt (CF) cathode. At room pressure, a slow removal of maleic acid was obtained, together with the generation of formic acid. Conversely, using pressurized air, the removal of maleic acid was dramatically accelerated and the formation of formic acid was not detected. The utilization of a carbon felt modified by the deposition of carbon black + PTFE mixture (MCF) and of pressurized air allowed to achieve even faster and almost total (>95%) removal of total organic carbon (TOC). Interestingly, the abatement resulted higher than the one obtained previously by direct anodic oxidation at boron doped diamond under comparable conditions. Similarly, in the case of Acid Orange 7 (AO7) the removal of the TOC increased with the pressure using both CF and the MCF. In particular, high removal of TOC (close to 80%) was obtained using the MCF at high current density (100 mA cm−2) under pressurized air.