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

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 center dot-/SO5- and O-2(center dot-) 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 O-2(center dot-) 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.