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

Abstract

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 NiFe₂S₄ can degrade 99.8% MB solution within 6 min in the presence of 5 mM H₂O₂ and natural pH. The recycle experiments results indicate that the NiFe₂S₄ catalyst possessed better stability than NiFe₂O₄. Furthermore, NiFe₂S₄ 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 NiFe₂S₄ is 73.1% in 30 min. A possible mechanism was proposed, and the degradation products were measured by LC-MS.