Preparation Of Mn-zn Ferrite From Spent Zn-Mn Batteries Using Bioleaching Liquor As Precursor And Its Application In Water Treatment

Synthesis of wide-application Zn-Mn ferrite soft magnetic materials using spent Zn-Mn batteries as starting raw materials has attained growing attentions in recent years. The multi-step series processes of reductive acid leaching and oxidative co-precipitation and high temperature calcination or hydrothermal reaction were generally utilized to carry out the conversion. In this work, a novel multi-step process of bioleaching and co-precipitation and boiling reflux, which was characteristic of low cost, environmental friendliness and energy saving, was attempted to accomplish the conversion using the pilot-scale device for the first time.X-ray diffraction(XRD), scanning electron microscopy(SEM), Transmission electron microscope(TEM), vibrating Sample magnetometer(VSM) and BET were used to characterize the structure, morphology and magnetism of the synthesized Mn-Zn ferrtie. The result indicates that the as-prepared Mn0.6Zn0.4Fe2O4 particles with average size of 20-50 nm, 19.346 m2/g of specific surface area and 97.86 emu/g of magnetization, are regularly dispersed. Their XRD pattern can be indexed to a pure cubic spinel structure. The as-prepared Mn0.6Zn0.4Fe2O4 can be easily magnetic separated when it is used as absorbent and photocatalyst.The absorption ability was investigated through the absorption of Cd(II)、As(III)and Pb(II) using Mn0.6Zn0.4Fe2O4 as absorbent. The result indicates that Mn0.6Zn0.4Fe2O4 is a kind of competitive absorbent that is sensitive to the operating condition such as pH, temperature and density. It is proved that the reaction follows the pseudo-second-order reaction kinetics and Langmuir isotherm equation.The photocatalytic activities of the as-prepared Mn0.6Zn0.4Fe2O4 are investigated through the photo-electrodegradation of methylene blue solution under visible light irradiation. It was found that over 97% of methylene blue was degraded with the Mn0.6Zn0.4Fe2O4 as photocatalyst. The related mechanism was further investigated to show that apart form the OH·generated by H2O2 through Mn0.6Zn0.4Fe2O4 catalyzed,which is main reason of the degradation of methylene blue, Fenton like reaction was also found during this process. In addition, photocrrosion occurred inevitably.