High degradation efficiency of sulfamethazine with the dual-reaction-center Fe–Mn–SiO2 Fenton-like nanocatalyst in a wide pH range

Abstract

The development of a heterogeneous Fenton-like catalyst, possessing a high degradation efficiency in a wide pH range, is crucial for wastewater treatment. An Fe–Mn–SiO₂ catalyst was designed and prepared by a hydrothermal method. Density functional theory (DFT) calculations demonstrated that the dual reaction centers were produced around the Fe and Mn atoms, due to valence-electron density distribution. The Fe–Mn–SiO₂ catalyst with dual reaction centers was applied for sulfamethazine (SMT) degradation in the Fenton-like process at a pH value of 4.0–8.6. Almost 100% SMT degradation efficiency was achieved under neutral pH at room temperature within 180 min. Moreover, the Fe–Mn–SiO₂/H₂O₂ system showed a high degradation efficiency (60–100%) for removing a wide range of aromatic pollutants, including bisphenol A, phenol, 4-chlorophenol, phenytoin, and ibuprofen. Besides, this process showed strong resistance to interference of inorganic anions (Cl⁻, SO₄²⁻, NO₃⁻ and HCO₃⁻). Electron paramagnetic resonance and radical scavenger experiments confirmed that the generated ¹O₂ and O₂˙⁻/HO₂˙ played an important role in the degradation of organic pollutants. In the Fe–Mn–SiO₂/H₂O₂ system, the electron-rich center around Fe was responsible for the reduction of H₂O₂ to ¹O₂, O₂˙⁻/HO₂˙ and ˙OH radicals, and then the electron-poor center around Mn adsorbed pollutants and transferred electrons to the electron-rich center around Fe via the Fe–O–Mn bridge.