Degradation of bisphenol A by peroxymonosulfate activated with oxygen vacancy modified nano-NiO-ZnO composite oxides: A typical surface-bound radical system

In this paper, a composite oxide catalyst consisting of NiO and ZnO was prepared by homogeneous precipitation method, which was used to activate peroxymonosulfate (PMS) to remove bisphenol A (BPA) in water. 95.26% BPA removal and 67.11% total organic carbon (TOC) removal were obtained under the optimum condition. Characterization and theoretical calculations (DFT) of the catalyst proved that electron rearrangement occurred in oxygen vacancy modified heterojunction catalysts. It resulted in the formation of acidic sites (NiO) and alkaline sites (oxygen vacancies) on the surface of the catalyst, thus promoting the adsorption and activation of PMS. According to the quenching experiments, a typical surface-bound radical reaction system was proposed. The reactive oxygen species (ROS) in the system were surface-bond SO4 center dot-, surface-bond (OH)-O-center dot and O-1(2). Finally, the BPA degradation pathways and the activation mechanism of PMS were analyzed in detail.