Visible light assisted peroxymonosulfate activation by NiO/SnO2 composite for efficient tetracycline degradation

Abstract

The hybrid of NiO/SnO2 was synthesized using a simple method and employed in peroxymonosulfate (PMS) activation for tetracycline (TC) degradation. Various characterization methods were applied to identify the physicochemical properties of NiO/SnO2. The formation of the NiO/SnO2 heterojunction significantly improved the activation performance of PMS, resulting in 90.2% TC degradation within 20 min under visible light irradiation. Furthermore, the excellent degradation performance can be maintained in different aqueous substrates, and a variety of anions had a slight effect on the TC degradation process. Free radical quenching experiments and electron paramagnetic resonance technology confirmed that superoxide radical (O2•-), singlet oxygen (1O2), hydroxyl radical (OH•) and sulfate radical (SO4•-) clusters were responsible for TC degradation. Liquid chromatography/mass spectrometry (LC/MS) technology and Toxicity Estimation Software Tool (T.E.S.T) were used to detect the intermediates and toxic changes in the degradation process of TC. In addition, a possible degradation path of TC was also proposed. Overall, this work provides new insight into PMS activation in antibiotic degradation by tin-based catalysts.