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Preparation And Properties Of Unmodified And Modified Fe3O4 Particles

Posted on:2015-02-12Degree:MasterType:Thesis
Country:ChinaCandidate:N H HuangFull Text:PDF
GTID:2191330473952176Subject:Materials engineering
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Due to their high surface energy, large specific surface area, small particle size and other special properties, magnetic nanoparticles have a wide application in various fields. Compared with the conventional magnetic materials, it exibites advantages, such as small size effect, quantum size effect, macroscopic quantum tunneling effect and superparamagnetic effect. Many researchers have been attracted by the superiority of Fe3O4 magnetic particles in the varied preparation methods and readily availablity of raw materials and other marvelous properties. Particularly, lower toxicity, good biological compatibility and biodegradability in vivo exibit the potential and valuble application of Fe3O4 magnetic particles in the biomedical fields.Common Fe3O4 magnetic particles are black powder crystals with inverse spinel structure, which belongs to the cubic crystal system. In humid enviroment, Fe3O4 is easy to be oxidized into Fe2O3. There are many methods to prepare Fe3O4, including microemulsion method, sol-gel method, hydrolysis method, hydrothermal method, co-precipitation method, etc. However, all these methods have their own inherent drawbacks, so how to obtain Fe3O4 nanoparticles with high saturated magnetic intensity, small particle size, dispersity and stability in aqueous solution has been a research focus. Among them, because of its simple preparation process, easy accessibility of equipment and productbility in large scale, co-precipitation method becomes the most used way in the application. Co-precipitation method is used in this thesis to prepare Fe3O4 magnetic particles by adjusting reaction time, reaction temperature, concentration of ferric ion, molar ratio of ferric and ferrous salt, concentration of hydrochloric acid, concentration of ammonia, stirring speed, etc. Under the optimized condition,different compounds, such as dihydroxy and trihydroxy small molecular compounds( ethylene glycol and glycerol), varied molecular weight of double hydroxyl polymer(polyethylene glycol), multi-hydroxyl polymer(polyvinyl alcohol), single carboxyl polymer(oleic acid), multi-carboxyl polymer( polyacrylic acid) are separately used as the agents to modify the surface of Fe3O4 magnetic particles. The obtained particles are characterized by X-ray diffraction(XRD), dynamic laser light scattering(DLS), Fourier infrared spectroscopy(FTIR), scanning electron microscopy(SEM), and vibrating sample magnetometer(VSM).The results show that the optimized preparation conditions are as follows: NH3·H2O:Fe3+=15, Fe3+:Fe2+=1:2, 0.01mol/L of HCl, 0.58mol/L of ferrous and ferric salts, 1h of reaction time, 90℃, 1000r/min.When PEG400 is used as the modified agent, Fe3O4 magnetic particles with best properties are obtained. It is proved that the surface of Fe3O4 can be covered by PEG, which improves the stability and dispersity of particles in aqueous solution. After modified by PEG400, the obtained Fe3O4 magnetic particles display good crystallinity and magnetic performace as follows: 16.4nm of the grainsize, 142.1±3.3nm of diameter in the aqueous solution, 78.6emu/g of saturated magnetic intensity, 180.0Os of coercivity and 23.8emu/g of remanence.
Keywords/Search Tags:Fe3O4, magnetic particles, co-precipitation, surface modification, biomedical
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