Persulfate activation by magnetic γ-Fe2O3/Mn3O4 nanocomposites for degradation of organic pollutants

In this work, magnetic gamma-Fe2O3/Mn3O4 nanocomposites with various mass ratios were successfully fabricated using a facile two-step method. Then these composites were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microcopy (TEM), X-ray photoelectron spectra (XPS) and vibrating sample magnetometer (VSM) measurements. Besides, the samples were applied to activate per sulfate for Rh B degradation. Results showed that the sample with a gamma-Fe2O3/Mn3O4 mass ratio of 3:1 exhibited higher activity than other gamma-Fe2O3/Mn3O4 nanocomposites, pure gamma-Fe2O3 and pure Mn3O4, where 95.1% of Rh B could be decomposed within 150 min in the presence of persulfate. In addition, effects of operational parameters on the catalytic activity of Rh B were also evaluated, which included persulfate concentration, catalyst dosage, reaction temperature and initial pH value. More importantly, the as-fabricated gamma-Fe2O3/Mn3O4 nanocomposites revealed magnetism and could be separated conveniently through external magnetic, which was beneficial to recycle the catalysts from the aqueous solution. Finally, the mechanism of activating persulfate by gamma-Fe2O3/Mn3O4 nanocomposites was proposed based on the results and literatures, which might provide a reference for further study of heterogeneous catalysis.