A novel peroxymonosulfate activation process by periclase for efficient singlet oxygen-mediated degradation of organic pollutants

Abstract

In this study, a novel peroxymonosulfate (PMS) activator, periclase (MgO) was applied to the activation of PMS for the degradation of organic contaminants in aqueous solution. It was found that MgO exerts an excellent and stable catalytic performance for PMS activation to degrade a wide range of pollutants including bisphenol A (BPA), phenol, chlorophenol, and dye, with degradation efficiencies of 100%, 100%, 41%, and 59%, respectively. Results from a combination of electron spin resonance (ESR), free radical quenching, chemical probe and isotope labeling investigations confirm that singlet oxygen (1O2) was the dominant reactive species generated in the PMS/MgO system and accounted for BPA degradation. The steady-state concentration of 1O2 was 13.2 × 10−13 M. Further evidence from X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectroscopy, and density functional theory (DFT) suggested that 1O2 was generated by the self-decomposition of PMS induced by surface hydroxyl groups on MgO. In addition, the degradation of BPA was hardly affected by anions and humic acid (HA) that commonly existed in the environmental matrices. The naturally occurring periclase also has high catalytic ability for PMS activation and BPA degradation. Compared with other transition metals-based radical pathways and carbonaceous materials-based non-radical pathways of PMS activation, MgO exerts a comparable catalytic performance but less potential risk and cheaper. This study developed a novel environmentally friendly catalyst with low cost and high efficiency for the selective degradation of organic pollutants in wastewater treatment.