Strong Visible Light Photocatalytic Activity of Magnetically Recyclable Sol–Gel-Synthesized ZnFe2O4 for Rhodamine B Degradation

Visible light-responsive ZnFe2O4 photocatalyst with a spinel structure was synthesized via a sol-gel method. The visible light photocatalysis of ZnFe2O4 was investigated by decomposing Rhodamine B (RhB) solution. Under ∼30 min of visible light irradiation, the decomposition ratio of RhB is up to ∼97.4%. The excellent photocatalytic performance of ZnFe2O4 photocatalyst is attributed to the high effective oxidation–reduction reaction caused by light irradiation excitation. With the increase of decomposition time, the wavelength of the maximum absorption peak of RhB solutions shifts from 557 nm to 498 nm (“blue shift”), which is because of the N-deethylation and cleavage of the conjugated chromophore structure of RhB. ZnFe2O4 photocatalyst also exhibits a weak ferromagnetism performance. The decomposition ratio of RhB for the magnetically recycled ZnFe2O4 is ∼94.6%. Strong visible light photocatalysis and convenience of magnetic recycling make ZnFe2O4 promising for photocatalytic applications in dye wastewater treatment.