Weak magnetic field enhances the activation of peroxymonosulfate by ZnO@Fe3O4

Abstract

The effect of weak magnetic field (WMF) on Acid Orange 7 (AO7) removal by ZnO@Fe₃O₄/peroxymonosulphate (PMS) was investigated. The results showed that the AO7 sequestration rate enhanced progressively to 0.14183 min⁻¹ in the presence of WMF, approximately 3 times the 0.04966 min⁻¹ in the absence of WMF. SO₄˙⁻/SO₅˙⁻ and O₂˙⁻ radicals were generated from the decomposition of PMS catalyzed by ZnO@Fe₃O₄ causing the degradation of AO7. In addition, a weak magnetic field promoted the production of O₂˙⁻ radicals and transition of Fe³⁺ to Fe²⁺. Radical-pair theory was used in this study to describe the role of WMF and a possible reaction mechanism was derived. Based on that, the influence of magnetic field flux intensity, pH and the reusability of ZnO@Fe₃O₄ were investigated in this paper.