Preparation, Modification And Application Of Fe₃O₄ Nanomaterials

In this paper, magnetic nanoparticles have been prepared by precipitation from partial oxidation of Fe2+ using oxygen in the air as natural oxidant, which are superparamagnetic and have high stablity. Besides, through the esterification of hydroxyl on the surface of Fe3O4 and oleate sodium, core-shell Fe3O4@oleic has been synthesized which has excellent hydrophobicity and can form magnetic fluid when dispersed in organic solvent. Furthermore, we have also prepared Fe3O4/Polystyrene (Fe3O4/PS) nanocomposites by micro-emulsion method. The properties and formation mechanisms of the products have also been investigated.The main contents are summarized as follows:Superparamagnetic Fe3O4 nanoparticles were synthesized using a simple and rapid method by precipitation from partial oxidation of Fe2+ under mild conditions, without any additional agent and inert gas. With pH, reaction temperature and time as main parameters, we have designed orthogonal experiments and studied the characterization and property in the optimum conditions.The result shows that products with octaheral, quasi-sphere and plate morphologies are obtained from various alkali source. We not only provided a simple and feasible method for other similar preparation of nanomaterials, but also provided a valid reference for those who want to get different shapes through changing the reactants.Magnetic nanoparticles of octaheral and quasi-sphere morphologies have been dispersed in double-distilled water, then an appropriate amount of sodium oleate is added. Through the esterification of hydroxyl on the surface of Fe3O4 and sodium oleate, we have synthesized Fe3O4@oleic core-shell materials which are superparamagnetic. It is proved that the content of oleic acid is just several percent by TGA. After modification, although thickness of the shell is very thin, we have realized the conversion from the original hydrophilic surface to hrdrophobic surface successfully. Furthermore, the nanoparticles prepared by this experiment can be dispersed in organic solvents to form magnetic fluid which has excellent magnetic response and stability, and has potential applications in the fields of magnetic fluid sealing and mineral porcess.Fe3O4@oleic core-shell nanomaterials are first dispersed in styrene. Then surfactant SDS is added, and in situ polymerization of styrene will happen on the surface of Fe3O4. Finally, Fe3O4 /PS nanocomposites are prepared by this method. Furthermore, the properties are characterized and the influence of morphology and surfcant have been studied.