Phenol degradation in a bipolar trickle tower reactor using boron-doped diamond electrode

Abstract

Electrochemical oxidation of phenol was studied in a bipolar trickle tower reactor using Raschig ring shaped boron-doped diamond (BDD) electrodes in recirculated batch mode. The model wastewater was prepared with phenol using distilled water. The effects of initial phenol concentration, concentration of Na2SO4 as a supporting electrolyte, current density, flow rate, and initial pH on the removal efficiency were investigated. The removal of phenol of 200 mg/L and chemical oxygen demand (COD) of 480 mg/L were achieved with efficiencies of 99.85 and 88.89%, respectively. In the same study, specific energy consumption of 0.676 kWh/g phenol removed was determined at the current density of 5 mA/cm(2). On the other hand, for the initial phenol concentration of 500 mg/L and COD of 1,200 mg/L, 99.69 and 90.83% removal efficiencies were obtained at the current density of 5 mA/cm(2), respectively. Microtox toxicity tests were performed to investigate the toxicity reduction potential of BDD anodes, and relatively good toxicity reductions were obtained with respect to the initial values. After determining optimum experimental conditions, petroleum refinery wastewater was also studied by monitoring the destruction of phenol and COD. In this study, phenol removal of 99.53% and COD removal of 96.04% were achieved at the current density of 5 mA/cm(2). Chemical oxidation studies were also carried out and the results were compared with the electrochemical oxidation studies. According to the whole results, it can be said that Raschig ring shaped BDD anodes exhibited an excellent performance for the degradation of phenol and COD and for the reduction of toxicity.