Electrochemical Degradation of Pharmaceuticals Using Ti/SnO2-Sb2O5-IrO2-RuO2 Anode: Electrode Properties, Performance and Contributions of Diverse Reactive Species

Abstract

Non-biodegradable pharmaceuticals are a group of emerging contaminants that have gained much attention because of their potential risk of inducing adverse ecological and health effects. An efficient Ti/SnO2-Sb2O5-IrO2-RuO2 electrode was prepared by Pechini method and employed as the anode for electrochemical degradation of selected pharmaceuticals (i.e., ibuprofen, atenolol, and carbamazepine). Compared its counterparts, Ti/SnO2-Sb2O5-IrO2-RuO2 exhibited higher oxygen evolution potential, lower chlorine evolution potential, larger active area, and higher stability. Unlike the negligible effect of solution pH from 4.0 to 10.0, increasing current density favored the target pollutants and COD removal. The removal of IBU was mainly attributed to the reaction with •OH, the contribution of which to IBU removal was enhanced with increasing current density. In contrast to IBU, the removal of ATEN and CBZ was mainly ascribed to the reaction with selective radical chlorine species (RCS) mainly in the form of Cl•, which was produced from direct oxidation of Cl− or indirect oxidation by •OH. It was found that the removal of ATEN and CBZ was less affected by dissolved organic matter (DOM) than that of IBU in municipal effluent. This study demonstrates that Ti/SnO2-Sb-RuO2-IrO2 is an attractive electrode for the destruction of pharmaceutical contaminants.