Core–shell Fe–Fe2O3 nanostructures as effective persulfate activator for degradation of methyl orange

In this study, core–shell Fe–Fe2O3 nanostructures (FNs) were used to effectively activate sodium persulfate (Na2S2O8) to induce sulfate radicals (SO4-) oxidation of methyl orange (MO) in aqueous solution (FNs/Na2S2O8). In this FNs/Na2S2O8 system, an enhanced degradation of MO was achieved in comparison with the Fe2+/Na2S2O8Fe2+/Na2S2O8 system using ferrous ions as persulfate activator under neutral pH condition. An acid pH and a high persulfate to FNs molar ratio (Na2S2O8:FNs) were favorable to the MO oxidation in the FNs/Na2S2O8 process. We characterized the prepared FNs and the used FNs during the FNs/Na2S2O8 process via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) systematically. On the basis of the degradation and characterization results, we proposed a mechanism for the degradation of MO in the FNs/Na2S2O8 process, which involved in situ homogenous and heterogeneous activation of persulfate simultaneously.

► FNs could activate Na2S2O8 to generate sulfate radicals effectively.
► FNs/Na2S2O8 system showed an enhanced activity on degradation of MO.
► Sulfate radicals were responsible for degradation of MO in the FNs/Na2S2O8 system.