Weak magnetic field enhances the activation of peroxymonosulfate by ZnO@FeO.

The effect of weak magnetic field (WMF) on Acid Orange 7 (AO7) removal by ZnO@FeO/peroxymonosulphate (PMS) was investigated. The results showed that the AO7 sequestration rate enhanced progressively to 0.14183 min in the presence of WMF, approximately 3 times the 0.04966 min in the absence of WMF. SO˙/SO˙ and O˙ radicals were generated from the decomposition of PMS catalyzed by ZnO@FeO causing the degradation of AO7. In addition, a weak magnetic field promoted the production of O˙ radicals and transition of Fe to Fe. 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@FeO were investigated in this paper.