Template-Based Fabrication of Copper Oxide for Persulfate Activation: Investigating Non-radical Mechanisms in Efficient Bisphenol a Degradation

Abstract

Currently, advanced oxidation processes (AOPs) are an efficient method for the degradation of recalcitrant organic pollutants. In this work, copper oxide (CuO) catalysts were synthesized using mesoporous silica (SiO₂) as a template for the activation of peroxomonosulfate (PMS) for the removal of the target pollutant bisphenol A (BPA). The results showed that the CuO catalysts not only increased the specific surface area and active sites, but also enhanced the efficient activation of PMS to produce a large amount of reactive oxygen species. In this paper, the degradation process and mechanism of BPA by CuO in PMS activation system were comparatively investigated by characterization data and experimental data. Under the optimum conditions, the degradation rate of BPA (30 mg/L) was as high as 97.8%, which was basically completely degraded. The CuO/PMS catalytic system involves both radical and non-radical pathways, with the non-radical ¹O₂ being the main reactive oxygen species for the degradation of BPA. The reaction intermediates were identified by liquid chromatography–mass spectrometry (LC–MS), and the degradation mechanism and the degradation pathway of the catalyst were proposed. It was shown by cycling experiments that the degradation rate of BPA in the system reached more than 65% at 60 min when the catalyst CuO was reused for the fifth time. This indicates that CuO has good stability. This study provides strong evidence that ¹O₂ is the main active agent for degradation in the PMS-induced inhomogeneous catalytic oxidation system.