Electrochemical activation of peroxydisulfate by Ti/ATO electrode: Performance and mechanism

Abstract

Antimony-doped tin oxide electrode (Ti/ATO) has received much attention in electrochemical water treatment owing to its high oxygen evolution potential (OEP) and low cost. This study mainly focuses on the electrochemical activation behaviour of peroxydisulfate (PDS) using a Ti/ATO electrode. The catalytic performance of the Ti/ATO-electro-activated PDS system was systematically investigated. The effects of different operating conditions on the RhB degradation rate, including electrolyte pH, PDS concentration, current density, and coexisting anions, were experimentally analysed. Quenching experiments, EPR, and electrochemical methods were used to identify the dominant reactive oxygen species (ROS) induced in the Ti/ATO electro-activated PDS system. Diverse radical and non-radical oxidations were verified to exist in the Ti/ATO electro-activated PDS system. We simulated the proposed reaction pathways of persulfate ion on the SnO2 surface using first-principles calculations. Computational results imply that persulfate ions are more easily activated into SO4− when adsorbing on the surface of SnO2. Furthermore, all the feasible oxidation processes which had made contribution to the RhB removal in Ti/ATO electro-activated PDS system were discussed. This work offers a new and effective strategy for electrochemical PDS activation and a viable technique for wastewater treatment.