Synthesis And Properties Of MFe₂O₄(M=Mn, Zn, Co, Ni, Cu) With Different Morphologies

Spinel ferrites MFe2O4 (M=Mn, Zn, Ni et al.) have attached many attentions for their excellent physical and chemical properties. The nanoscale ferrites are applied widely in various fields with the development of nanotechnology. Since the structure and properties of ferrites can be affected by their morphologies, ferrites with different morphologies (nanorod, nanofibcr, olivary and pores) are synthesized by the routes of combining the suit growth method and simple hydrothermal/solid-state routes, without any template or active surfactant. The synthesis conditions, structures, morphologies, magnetic and adsorption properties are investigated. The formation mechanisms of NiFe2O4 nanofibers and 3D macroporous NiFe2O4 are studied. In addition, since the porous structure suit for adsorption, the porous ferrites are applied in the treatment of wastewater and the adsorption mechanism is studied by effect factors, adsorption kinetic and adsorption isothermal.The syntheses of complex oxides using binary oxide as raw materials by simple routes are realized by combining the seed growth method and traditional hydrothermal/solid-state method. The special shape ferrites are difficult to synthesize without template or active surfactant due to their complex structures. However, the nanorod, nanofiber and olivary spinel ferrites are synthesized by seed-hydrothermal and seed-solid-state routes in this work. And the morphologies can be controlled by synthesis conditions. During this synthesis process, simple oxide are synthesized by coprecipitation firstly, and then used as seed to fabricate the ferrites with nanofiber and olivary morphologies. In addition, the mechanism of synthesizing nanofiber ferrite by seed-solid-state route is studied.3D-macroporous ferrites are synthesized by sol-gel method with egg white as ligand. This realized the synthesis of 3D macroporous ferrites with simple route and by biologic raw materials. And find that the synthesis condition related to the pore size of porous ferrites. In addition, the mechanism of forming pores in the process of synthesizing spinel ferries by this route is pointed out.The porous ferrites are applied in the treatment of wastewater containing organic dyes and heavy metal ions. The results showed that all ferrites have obvious adsorption of organic dyes (MB and FR) and heavy metal ions (Cu (â…¡), Cr (VI) and Ni (â…¡)). The ferrites can be separated from solution after adsorption easily, due to their ferromagnetic properties. The separated ferrites can be reused many times keeping high adsorption activities, and the rates of adsorption in the reused cycles are even higher than that in the first cycle. The best adsorption conditions are investigated by the studies of the effect factors of organic dyes adsorption on ferrites.In addition, the adsorption mechanism of organic dyes on ferrites is studied by FT-IR analysis, adsorption kinetic and adsorption isothermal. Results showed that the Fe-O bond of ferrite is responsible for good adsorption, the adsorptions of MB and FR fit pseudo-second-order kinetic model, Langmuir isotherm equation well.The effects of ions substitution on ferrites'structure, morphologies, magnetic and adsorption properties are studied. Results showed that the ions substitution can change ferrites'structure and morphologies, and reasonable substitution can enhance their magnetic and adsorption properties.