Design, Synthesis And Applications Of Magnetic Metal-Organic Framework Composites With Core-Shell Structure

As a new class of porous materials, Metal-Organic Frameworks (MOFs) represent a new class of hybrid organic-inorganic surpramolecular materials comprised of ordered networks formed from organic bridging ligands and inorganic metal cations. They have attracted significant research interest in recent years, not only for their fundamental scientific interest,but also for many attractive applications in catalysis, selective adsorption and separation, gas storage, and drug delivery. However, these traditional photocatalysts and the MOF-type materials are difficult to separate from large volumes of reaction solutions when applied to adsorption and catalysis. Therefore, the development of a novel multifunctional magnetic core@MOF shell microspheres which can offer the provision to the advantages of a porous shell and magnetic responsiveness is needed, The magnetic core@MOF shell materials have potential applications in recyclable catalysts, magnetic separation and targeted drug delivery.In this work, we describe novel multifunctional magnetic Fe3O4@MIL-100(Fe) core-shell microspheres, by a versatile layer-by-layer strategy and hydrothermal synthesis method, respectively, and demonstrate the functionlization of these core-shell microspheres in the degradation of organic dye. The main contents of this thesis are as follows:1. we successfully synthesized hierarchically structured MIL-100(Fe) MOFs as a new photocatalyst to treat methylene blue (MB) dye. The structures of MIL-100(Fe) were confirmed by PXRD, SEM, and nitrogen adsorption-desorption isotherms at77K. It was found that MIL-100(Fe) exhibited photocatalytic activity for MB dye degradation under both UV-vis and visible light irradiation, The results of photocatalytic degradation MB show this kind of material provides an efficient platform for MB photodegradation, which also provided an opportunity to design a new convenient photocatalytic material.2. A novel multifunctional magnetic Fe3O4@MIL-100(Fe) core-shell microspheres, with a much more controllable manner were fabricated by a versatile layer-by-layer strategy. The microspheres were characterized by Powder X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and transmission electron microscopy (TEM). The representative SEM and TEM images clearly show that magnetite particles are individually coated with a uniform MIL-100(Fe) shell, and the shell thickness could be easily tuned by varying layer number coated on the magnetic core. Magnetic tests show that the magnetic Fe3O4@MIL-100(Fe) core-shell microspheres composites have excellent magnetic properties. The results of photocatalytic degradation MB show that the Fe3O4@MIL-100(Fe) photocatalyst exhibited remarkable photocatalytic activity for MB decolorization comparison with typical photocatalysts, such as TiO2, C3N4and N-TiO2. Moreover, the as-synthesized material exhibited good magnetic characteristics, which making it an excellent candidate for designing and synthesizing a novel kind of highly active photocatalyst for the decolorization of organic pollutants.3. We report for the first time the rapid fabrication of magnetically separable Fe3O4@MIL-100(Fe)core-shell microspheres with different proportions of Fe3O4and MIL-100(Fe) by the hydrothermal method. The size of the Fe3O4@MIL-100(Fe) could be easily tuned by varying the proportions of MIL-100(Fe). In this work, the adsorption of the methyl orange (MO) from aqueous solution on magnetic Fe3O4@MIL-100(Fe) core-shell microspheres was studied in view of the adsorption isotherm, kinetics, and regeneration of the sorbent. Based on the experimental results, the sample shows good adsorption capacity in MO adsorption Furthermore, the magnetic Fe3O4@MIL-100(Fe) core-shell microspheres are reusable after adsorption in water and could be effectively and easily separated by applying a magnetic field after adsorption.