Decomposition of perfluorooctanoic acid from wastewater using coating electrode: efficiency, the anode characteristics and degradation mechanism

[Display omitted] •Ti/SnO2-ZnO anode was used to degrade perfluorooctanoic acid.•The properties of three composite electrodes were comparad.•Ti/SnO2-ZnO electrode has good stability and electrochemical oxidation.•The optimal removal rate of perfluorooctanoic acid reached 86.17%. Perfluorooctanoic acid (PFOA) was a persistent pollutant that exists in many environmental media. In this research, two kinds of metal additive (Zn, Ru) were applied to Titanium substrate to obtain suitable coating materials for PFOA degradation in sewage. Three compound materials were compared to confirm the removal efficiency of PFOA under different electrolytic conditions and the stability of coating, and the Ti/SnO2-ZnO was determined to the most suitable anode. The cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) were employed to analyze the modification properties of Ti/SnO2-ZnO anode at the same. The impact of different working conditions included three factors: pH, current density, and initial concentration. When Ti/SnO2-ZnO anode was evaluated, in order to achieve optimum effects (86.17%), it should be proved that pH was 6, current density was 16 mA/cm2 and initial concentration was 10 mg/L. The excellent stability of electrode was detected by five parallel experiments. Besides, the experiment determined the degradation kinetics, and it further explored the removal mechanism, as well as the pathways of PFOA degradation by Ti/SnO2-ZnO anode through the analysis of decomposition intermediates. The results showed that PFOA degradation was a directly mineralization and underwent complex reactions, observing the pseudo-first-order kinetic equation appropriately.