Preparation and Evaluation of a Photo-Fenton Heterogeneous Catalyst: Spinel-typed ZnFe2O4

In this study, spinel-typed ZnFe2O4 was synthesized through Sol-Gel method, using fresh egg white as a complexing agent, and characterized by XRD and SEM. Then, the synthesized sample was used as the photo-Fenton heterogeneous catalyst for the discoloration of methyl orange (MO) in solution. The XRD results show that the synthesized sample was pure, only with the spinel structure, when the volume ratio of the fresh egg white/ferric nitrate/zinc nitrate was 2:2:1. And the lowest sintered temperature to obtain the single-phase ZnFe2O4 was 500 degrees C. The SEM results reveal that the ZnFe2O4 crystalline grains presented irregular shapes and desultorily aggregated together, with a average diameter of 150-250nm. The experimental results show that MO could be efficiently discolored in photo-Fenton system of ZnFe2O4 and H2O2, under UV irradiation. MO discoloration ratio increased as H2O2 dosage increasing. The optimum dosage of ZnFe2O4 was 1g/L in this study. With the MO initial concentration increasing, MO discoloration ratio decreased. The ZnFe2O4 sample obtained at 500 degrees C exhibited the optimum MO discoloration ratio. Finally, the mechanism for MO discoloration in the photo-Fenton system was discussed.