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Preparation And Characterization Of Magnetic Mesoporous Silica Nanoparticles (Fe3O4@SiO2) With A Core-Shell Structure

Posted on:2013-01-13Degree:MasterType:Thesis
Country:ChinaCandidate:X BaiFull Text:PDF
GTID:2231330395986840Subject:Chemical processes
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Magnetic mesoporous silica nanoparticles have shown extensive applicationprospects in medicine, catalysis, and chemical industries for their goodbiocompatibility and unique magnetic properties. Magnetic mesoporous silicananoparticles with small and uniform pore size have recently been subject toextensive research for their advantages of biological functions. The preparationof the magnetic mesoporous silica composite nanoparticles with uniform particlesize distribution, high chemical stability, and good dispersion state in liquidphase has been researched largely as a hot topic in magnetism field.Core-shell structural magnetic mesoporous silica nanoparticles with Fe3O4as core and uniform pore canal of SiO2as shell were prepared by a sol-gelhomogeneous coprecipitation process, using Fe3O4that were prepared byhydrothermal-co-precipitation method as core, diethanolamine (DEA) ashomogeneous precipitating agent, tetraethoxysilane (TEOS) as the silicamaterials, cetyltrimethylammonium bromide (CTAB) as surfactant. DEA presentsthe dual nature of ammonia and alcohol, which can be partially ionized inaqueous solution to change the pH of the solution system and control the reactionrate effectively. Moreover, the hydroxyl (-OH) from DEA can combine withsilicon hydroxyl in the form of hydrogen bonds, which partially terminate thepolycondensation reaction of TEOS itself. Such conditions are beneficial for theformation of mesoporous structure.Through the comparing experiments at different reaction conditions on themagnetic nanoparticles and magnetic composite nanoparticles, the results showedthat, when pH=8, the reaction temperature of120°C, the surfactant molepercentage of0.003mol·L-1, Fe3O4nanoparticles were purity and small with average particle size of60nm. When pH=10, the reaction temperature of90°C,reaction time of6h, TEOS of1mL, CTAB mole percentage of0.002mol·L-1, themagnetic composite nanoparticles own uniform particle size and monodispersity.The composite nanoparticles were characterized by X-ray powderdiffraction (XRD), scanning electron microscopy (SEM), transmission electronmicroscope (TEM), laser particle size analyzer and nitrogen adsorption-desorption isotherm. The results indicate that the surface of Fe3O4nanoparticleswas successfully coated by the silica. The size of the nanoparticles was uniformwith an average diameter of120nm, surface area of768.5m2·g-1, average poresize of2.32nm and pore volume of0.23cm3·g-1. The magnetic mesoporousnanoparticles were of spherical in shape and monodispersed in appearance.
Keywords/Search Tags:mesopore, silica nanoparticles, Fe3O4, core-shell structure, magneticproperty
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