Insight into the degradation of p-nitrophenol by visible-light-induced activation of peroxymonosulfate over Ag/ZnO heterojunction

Abstract

In this report, the peroxymonosulfate activation over Ag/ZnO heterojunction under visible light (Ag/ZnO/PMS/Vis) for p-nitrophenol (p-NP) contaminant degradation was conducted in detail. Herein, the catalyst dosage was decreased, and the results showed that a dosage of 0.5 g L^-1 Ag/ZnO and 4 mM PMS almost completely degraded 30 mg L^-1 p-NP after 90 min of irradiation. In addition, the PMS activation mechanism of Ag/ZnO/PMS/Vis system was proposed by investigations of the influence of PMS concentration, the FTIR spectra, UV-Vis spectroscopy, and electrochemical analyses. Additionally, the role of SO₄^•- in the photocatalytic reaction is determined by a combination of a trapping test using isopropanol and tert-butanol as probe compounds and electron spin resonance (ESR) spectroscopy. This report provides a potential alternative to remove persistent organic contaminants in sewage using PMS incorporated with Ag/ZnO under visible light irradiation.

Keywords: Advanced oxidation process; Ag/ZnO heterojunction; Peroxymonosulfate; Photocatalysis; Visible light; p-nitrophenol.