Treatment of textile dye wastewater by peroxymonosulfate activation using facilely prepared Fe3O4@TiO2 heterogeneous photocatalyst

In this study, Fe₃O₄@TiO₂ was synthesized by a facile precipitation–impregnation method and applied as a magnetic photocatalyst for degrading synthetic and actual textile dyeing wastewater in the presence of peroxymonosulfate (PMS). In Rhodamine B (RhB) degradation, the removal efficiency reached 99.86% (for RhB) and 93.67% (for color) under optimal operating conditions of 80 mg L^–1 RhB, 0.5 g L^–1 PMS, 0.5 g L^–1 Fe₃O₄@TiO₂, at pH 6, and after 30 min of UVA irradiation. The influence levels of anions on the RhB removal and decolorization were in the order of Cl⁻ < SO₄²⁻ < CO₃²⁻ < PO₄³⁻. In addition, the Fe₃O₄@TiO₂ composite exhibited good applicability for treating other dyes (e.g., 99.6% of tartrazine and 60.3% of methylene blue after 30 min) in water and actual textile dyeing wastewater with high color (70.3% after 5 min) and COD removal (71.4% after 120 min). The radical scavenging tests indicated the role of reactive oxygen species in the order of O₂^•− ∼ ¹O₂ > h⁺ > SO₄^•− > HO^• for RhB degradation but O₂^•− > h⁺ > ¹O₂ > SO₄^•− > HO^• for decolorization. These results suggest the potential application of PMS activation using Fe₃O₄@TiO₂ in the photocatalytic treatment of textile and dyeing wastewater with the dominant role of O₂^•−.