Effects of La3+ doping on the structure, properties and application of Mn–Zn ferrite

Abstract

In this study, the La doped Mn–Zn nanoferrites were synthesized through hydrothermal method, and then were used to activate persulfate for degrading azo dye the Direct Blue 15 (DB15). The structure and morphology of the as-prepared sample were characterized by X-ray Diffraction (XRD), Fourier Transformed Infrared Spectrometer (FTIR), Transmission Electron Microscopy (TEM) and Energy Dispersive Spectrometer (EDS). The results indicated that the La doped Mn–Zn ferrite was successfully synthesized in this study. Four absorption bands were observed in FTIR spectra and assigned to the corresponding site bonds. Mn0.6Zn0.4LaxFe2-xO4 was chosen as catalysts to activate persulfate (PS/Mn0.6Zn0.4LaxFe2-xO4) to decolorize the DB15. It was found that the DB15 was degraded effectively by PS/Mn0.6Zn0.4LaxFe2-xO4 systems. Furthermore, the influences of synthesized conditions (such as the temperature, holding time and doping content of La) of Mn0.6Zn0.4LaxFe2-xO4 on the DB15 decolorization were analyzed. The results indicated that the doping of La can significantly improve the DB15 degradation, 100% degradation of DB15 can be obtained by PS/Mn0.6Zn0.4La0.09Fe1.91O4 within 15 min. The enhancement of synthesized holding time of Mn0.6Zn0.4LaxFe2-xO4 at 160 °C can also increase the DB15 decolorization, and the degradation rate of the DB15 reached almost 100% within 25 min when using Mn0.6Zn0.4La0.05Fe1.95O4 synthesized at 160 °C for 13 h as catalyst.