| With the development of nano-technology, magnetic ferric oxide nanoparticles are widely studied for their application in biomedical field such as cell separation, enzyme immobilization, immunoassay, drug delivery, DNA separation and so on.In addition, magnetic ferric oxide nanoparticles are also widely used as magnetic materials for information storage, catalyst, magnetic fluids, microwave absorbent et al.with the research to the depth and interdisciplinary cross-infiltration, the research on multi-functional magnetic ferric oxide nanoparticles applied to fields of biomedicine and biological Engineering such as drug delivery, separation of biological macromolecules, biosensors and immobilized enzyme becomes hot.The dissertation focuses on the preparation,surface modification and application of magnetic particles.It refers to the size-controlled synthesis of monodisperse Fe3O4 submicrospheres, the preparation of magnetic carboxymethyl chitosan-Fe3O4 particles and the adsorption behaviors of magnetic carboxymethyl chitosan-Fe3O4 particles in removing heavy metal ions, Pb2+ and Cd2+.The main content of the thesis is as follows:Size-controlled Synthesis and Characterization of Monodisperse Fe3O4 Submicrospheres:Fe3O4 submicrospheres were synthesized by the solvothermal synthesis at 200℃,using FeCl3·6H2O and ethylene glycol as reactants.The size of as-prepared Fe3O4 submicrospheres could be controlled in the range of 115-435 nm in diameter by adjusting some growth parameters.The structure, size, morphology and composition of the as-prepared Fe3O4 submicrospheres were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy(SEM).The results showed that the Fe3O4 submicrospheres were of inverse spinel structure. Magnetic property of 330 nm Fe3O4 submicrospheres has been detected by a vibrating sample magnetometer at room temperature. The coercive force, saturation magnetization and remanent magnetization of 330 nm Fe3O4 submicrospheres are about 83.5 Oe,81.2 emu/g and 14.6 emu/g, respectively. The influence of ethylene glycol,concentration of NaOH, and reaction time on the morphology development was experimentally investigated.It was found that ethylene glycol molecules have a significant effect on the formation of Fe3O4 submicrospheres.A possible mechanism was also proposed to account for the growth of these Fe3O4 submicrospheres.Preparation and characterization of magnetic carboxymethyl chitosan-Fe3O4 particles:Chitosan was carboxymethylated and was bound onto the surface of Fe3O4 particles, and then the magnetic carboxymethyl chitosan-Fe3O4 particles (Fe3O/4CMC) were gained. The obtained magnetic carboxymethyl chitosan-Fe3O4 particles (Fe3O4/CMC) were characterized by the images of TEM,XRD, Fourier transform infrared (FT-IR) and magnetometer measurements.TEM showed that the magnetic iron oxide particles were encapsulated by carboxymethyl chitosan. The particle size of Fe3O4/CMC was about 118 nm. XRD indicated that the composite magnetic particles were validated as the binding of chitosan on Fe3O4. FT-IR spectra confirmed the carboxylmethyl reaction of chitosan.The saturated magnetization of Fe3O4/CMC can reach 66.1 emu/g.Meanwhile, the particles showed high stability of magnetization.Adsorption behaviors of magnetic carboxymethyl chitosan-Fe3O4 particles in removing heavy metal ions, Pb2+and Cd2+:The magnetic carboxymethyl chitosan-Fe3O4 particles (Fe3O4/CMC) were used as a magnetic adsorbent, and the adsorption of heavy metal ions, Pb2+ and Cd2+, onto the magnetic carboxymethyl chitosan-Fe3O4 particles (Fe3O4/CMC) was studied.The results showed that the adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of Pb2+ 86.2 mg/g,Cd2+ 38.6 mg/g and a Langmuir adsorption equilibrium constant of Pb2+ 0.0291 L/mg,Cd2+ 0.0314 L/mg at 25℃.Adsorption rates were high, and adsorption equilibria were reached in about 50 min. Under non-competitive and competitive conditions the affinity order of ions was Pb2+>Cd2+.Desorption of heavy metal ions was achieved using 0.1 mol/L HNO3.It was observed that heavy metal ions could be repeatedly adsorbed and desorbed without significant loss in adsorption capacity.It would be used to remove heavy metal ions in wastewater. |
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