The design of efficient advanced oxidation processes (AOPs) in the presence of bicarbonate has long attracted considerable attention in the field of environmental catalysis. In this study, sodium bicarbonate (NaHCO3) as one of the most abundant substances in actual water, was introduced to a NaClO/Ru(III) system to enhance the removal of acid orange 7(AO7). NaHCO3 could significantly improve the removal efficiency of the Ru(III)/NaClO process in HCO3- at a pH range of 6.9-10.0. Ru(V)=O was identified as a dominant reactive species involved in the degradation of pollutants in the NaHCO3/NaClO/Ru(III) system. HCO3- interacts with Ru(III) to generate Ru(III)-HCO3-, which enhances the activation performance of Ru(III) under neutral or alkaline conditions. The removal of AO7 was significantly enhanced with increasing NaHCO3 concentration, and the rate constant increased more than 2-fold to 4-fold as NaHCO3 concentrations increased from 0 to 100 mM at pH 6.9 and 8.5. This study proposed a novel strategy to enhance the Ru(III)/NaClO process with environmentally friendly inorganic ligands and highlights its potential applications in the removal of pollutants.
Keywords: NaClO; Ru(III); Ru(V)=O; advanced oxidation processes; sodium bicarbonate.