The influence of anode materials on the kinetics toward electrochemical oxidation of phenol

Electrode performances of IrO2-Ta2O5/Ti and PbO2/Ti anodes were investigated by electrochemical measurements and phenol oxidation. The cyclic voltammetry (CV), polarization and electrochemical impedance spectroscopy (EIS) conducted in phenol solution indicate the oxidation ability of PbO2/Ti anode is higher than that of IrO2-Ta2O5/Ti electrode because it can reduce oxygen evolution and thus increase effective current. A novel parameter, gamma, associated with anode materials was proposed to quantitatively describe the effective current applied to main reactions and its value could be achieved through EIS fitted data of the components in equivalent electrical circuits (EEC). The suitability of the used EEC was checked by consistency of the exchange current density between Tafel plots and EIS data. With involvement of the novel parameter (gamma) into organics oxidation, a universal kinetics was thereafter presented to predict variations of chemical oxygen demand, average current efficiency and power consumption. The results of regression analysis and F-test show higher agreement between the experimental and model estimation during phenol oxidation, verifying necessity of the parameter gamma in characterizing effective current for anodic reactions and rationality of the kinetics in describing organics oxidation by different electrodes. (c) 2016 Elsevier Ltd. All rights reserved.