| Magnetic nanoparticles, owing to their specific superparamagnetic property, have been widely used in information storage, biomedicine, environmental remediation and other fields. For many applications, the controlled synthesis of magnetic nanoparticles with high magnetic response, narrow size distribution and aqueous stability is of primary importance. Graphene, a 2-dimensional nanomaterial found in 2004, has gained rapid development in recent years due to its excellent electronic, thermal, optical and mechanical properties. Integration of magnetic nanoparticles and graphene oxide into composite mateiral may find potential applications in materials, chemical and biological fields. This thesis report controllable assembly of Fe3O4 magnetic nanoparticles on the surface of graphene oxide (GO), and explored preliminarily application of this nanocomposite material in the removal of aromatic contaminants from waste water.In Chapter 2, high temperature decomposition approach was employed to synthesize monodisperse Fe3O4 magnetic nanoparticles with size of 3 nm,5 nm,6 nm, and 18 nm, respectively. The ligand-exchange method was used to modify the nanoparticles with amino and carboxy groups. The structure and magnetic properties of the magnetic nanoparticles were characterized. The results show that the we have successfully prepared monodisperse Fe3O4 nanoparticles with high magnetic response. The amino and carboxy group containing ligand modified magnetic nanoparticles are very stable in water.Chaper 3 describes preparation of Fe3O4 nanoparticle-GO composites by chemically binding carboxylic acid-modified Fe3O4 nanoparticles to polyethylenimine-functionalized GO. The structure, morphology and magnetic properties of the composites were characterized by transmission electron microscopy, atomic force microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis and vibrating sample magnetometry. We show that the Fe3O4 nanoparticle content in the MGO composites can be easily controlled by changing the ratio of Fe3O4 nanoparticles to GO in the reaction mixture. The composites obtained are superparamagnetic with high saturation magnetization, which can potentially be applied in magnetic targeted drug delivery, magnetic resonance imaging, bioseparation, magnetic guided removal of aromatic contaminants in waste water and in other fields.In Chapter 4, We describe a facile approach to controllable assembly of monodisperse Fe3O4 nanoparticles (NPs) on chemically reduced graphene oxide (rGO). First, reduction and functionalization of GO by polyetheylenimine (PEI) were achieved simultaneously by simply heating of PEI and GO mixture at 60℃for 12 h. The process is environment friendly and convenient compared with previously reported methods. Meso-2,3-dimercaptosuccinnic acid (DMSA)-modified Fe3O4 NPs were then conjugated to the PEI moiety which is located on the periphery of the GO sheets via formation of amide bond between COOH groups of DMSA molecules bound on the surface of the Fe3O4 NPs and amine groups of PEI. The magnetic GO composites are characterized by means of TEM, AFM, UV-vis, FTIR, Raman, TGA, and VSM measurement. Finally, preliminary result of using the Fe3O4-rGO composites for efficient removal of tetracycline, a widely existed antibiotic contaminant in environment, is reported.In conclusion, the current work deveolped convenient and efficient approaches for controlled assembly of Fe3O4 nanoparticles onto the surface of graphene oxide. The obtained nanocomposites exhibit tunable magnetic response, which may facilitates their widespread applications. |
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