Degradation of phenol using Co- and Co,F-doped PbO2 anodes in electrochemical filter-press cells

A comparative study on the electrooxidation of phenol in H2SO4 medium using pure PbO2 or F-, Co- and Co,F-doped PbO2 electrodes in filter-press cells was carried out. The oxide films were obtained by galvanostatic electrodeposition using an electrolytic bath containing sodium lauryl sulfate as additive and Pb2+, F−, Co2+ or Co2+ + F−, under magnetic stirring (to obtain 4-cm2 electrodes) or ultrasound waves (to obtain 63-cm2 electrodes). The best results were attained with PbO2 electrodes doped with a low-Co content (1 mM Co2+ in the electrolytic bath) along with F−: the chemical oxygen demand (COD) and the total organic carbon content (TOC) of the simulated wastewaters were removed by about 75% and 50%, respectively. When pure PbO2 electrodes were used, the COD and TOC removals were about 60% and 45%, respectively. For the smaller electrodes, an average current efficiency (ACE) and an energy consumption (EC) of about 16% and 70 kWh kgCOD−1, respectively, were obtained. For the larger electrodes, the ACE and EC values were about 18% and 105 kWh kgCOD−1, respectively. Stability tests of the electrodes showed that they are suitable for use in the electrochemical treatment of phenol wastewaters.