An efficient CuO-γFe2O3 composite activates persulfate for organic pollutants removal: Performance, advantages and...

CuO-γFe₂O₃ was fabricated as a novel and effective persulfate (PS) catalyst to remove bio-refractory organic pollutants. Characterization results showed that CuO-γFe₂O₃ possessed a relatively large surface area among transition metal oxides which provided favorable adsorption and activation sites for PS to degrade pollutants. There was an obvious synergy between CuO and γFe₂O₃ in the composite, which played 84.7% role in Acid orange 7 (AO7) removal. Under the optimal conditions (CuO-γFe₂O₃ dosage = 0.6 g L^-1, PS dosage = 0.8 g L^-1, unadjusted solution pH), almost complete AO7 was rapidly eliminated in 5 min. Moreover, the wide workable pH range (2-13), good stability (0.82 mg L^-1 Cu leached, almost no Fe leached) and reusability (4 times) were the significant virtues of CuO-γFe₂O₃ for wastewater treatment. Besides, the reaction mechanism mainly based on the interaction among Cu(II/III) and Fe(II/III) species for sulfate radical (SO₄^-) generation was emphatically elucidated by the analyses of radicals, PS utilization, TOC removal and metal chemical states. Finally, CuO-γFe₂O₃+PS system displayed desirable removal of multiple organic pollutants with different molecular structures. In light of the prominent advantages of CuO-γFe₂O₃+PS, this work extended activated PS process in treating refractory organic wastewater.