S-doped NiFe-based catalyst for fast degradation of methylene blue by heterogeneous photo-Fenton reaction

S-doped NiFe-based particles were prepared by a solvothermal method and used to degrade methylene blue (MB) aqueous solutions with visible light in a heterogeneous Fenton reaction. The obtained solid samples were characterized by XRD, SEM, TEM, and XPS. It was found that 0.2 g L −1 NiFe 2 S 4 can degrade 99.8% MB solution within 6 min in the presence of 5 mM H 2 O 2 and natural pH. The recycle experiments results indicate that the NiFe 2 S 4 catalyst possessed better stability than NiFe 2 O 4 . Furthermore, NiFe 2 S 4 particles can be easily separated from contaminant solution by using a magnet due to their excellent ferromagnetism. COD analysis experiments indicated that the COD removal rate of NiFe 2 S 4 is 73.1% in 30 min. A possible mechanism was proposed, and the degradation products were measured by LC-MS.