Influence of the Local Structure on the Photocatalytic Properties of Zinc Spinel Ferrite Nanoparticles

The correlation between iron distribution in octahedral or tetrahedral sites in synthetic magnetite and zinc spinel ferrites and their catalytic properties were investigated in this work. The zinc-doped nanomagnetites were prepared by co-precipitation method and annealed at 420 degrees C. X-ray diffraction, UV-Vis, X-ray absorption and Fe-57 Mossbauer spectroscopies were used to identify iron sites. The obtained results showed that Zn-II replaces the relatively smaller Fe-III cation in the tetrahedral sites, increasing the cubic lattice dimension, and this replacement remarkably enhances the catalytic effectiveness of the Zn-spinel ferrite towards the indigo carmine degradation compared to undoped magnetite. The indigo carmine degradation experiments were carried out using photo-Fenton method in which 50 mL of indigo carmine dye aqueous solutions (20 mg L-1, pH 3.0), 20 mg ZnxFe(3-x)O4, and 2.0 mL H2O2 (aqueous solution at 0.028 mol L-1) were placed under UV light at 25 degrees C. Under these experimental conditions the degradation rate of indigo carmine was superior to 98%.