Synthesis Of Iron Oxide Nanoparticles And Study Of Their Composite Materials

α-Fe2O3 and Fe3O4 are two important kinds of iron oxides.Forα-Fe2O3,because of its unique excellent properties, it is widely used as gas sensors,catalyst,pigment, electrode material,et.For Fe3O4,because of its magnetic property and biocompatibility, it is widely used in various fields,such as high-density magnetic recording media, ferrofluids,drug delivery,medical diagnosis,etc.Recent years,people become interested in the surface modification of Fe3O4,the composite nanoparticles not only keep the magnetic properties,but also have some new properties.In this dissertation, we have focused on the synthesis ofα-Fe2O3 and Fe3O4 nanoparticles,and doing some modification on the surface of Fe3O4. The detailed researches of the thesis are as follows:1.Synthesis ofα-Fe2O3 nanorods and nanocubes and their propertiesWe choosed FeCl3,CO(NH4)2 and soduim dodecyl benzene sulfonate(DBS) as raw materials,at first,α-FeOOH nanorods were synthesized,on one hand,α-Fe2O3 nanorods were obtained by calcination ofα-FeOOH nanorods,in this process,the product inherited the rod-like morphology;on the other hand,by controlling the amount of DBS in the hydrothermal system,we observed the direct transformation fromα-FeOOH toα-Fe2O3,what's more,the structure developed to nanocubes.We deeply investigated the role of the surfactant in the phase and morphology,proposed a possible mechanism.The optical and magnetic properties of theα-Fe2O3 nanorods and nanocubes were also studied.2.Synthesis of Fe3O4 nanoparticles and their propertiesIn this article we adopted a simple,controllable and easy solution-phase approach, using FeSO4 and (NH4)2CO3 as raw materials, water as solvent, Fe3O4 nanoparticles were prepared by refluxing method.The effect of reaction temperature and time on the formation of the products had been described in detail using X-ray power diffraction (XRD) and scanning electron microscopy (SEM).When the reaction temperature reached 80℃and the time reached 8h, quasi-octahedral crystal Fe3O4 nanoparticles were successfully prepared.The nanoparticles were proved to be stable enough by thermogravimetry(TGA).Vibrating sample magnetrometer(VSM) was employed to investigate their magnetic properties,their saturated magnetization reached as high as 81.24 emu/g.3. Synthesis of Fe3O4/SiO2/Chitosan composite nanoparticles and their propertiesChitosan has special physiological activity,nontoxicity,biodegradability, biocompatibility,etc.It has abundant chemical groups and it is an ideal modification of nanoparticles.In this article,we first coated silica on the surface of Fe3O4 composite nanoparticles,then combied with chitosan.The prepared Fe3O4/SiO2/Chitosan nanoparticles had some magnetic property and they were easy to separate.Heavy metal ions(Cr6+) acted as contamination model,we investigated the adsorption efficiency of the prepared nanoparticles,the rusult showed that the efficiency reached 72.6% and they would have optical application in sewage disposal.4.Synthesis of Fe3O4/polyaniline composite nanoparticles and their propertiesIn this article,we modified the surface of Fe3O4 with polyaniline by using solution polymerization,prepared Fe2O4/polyaniline composite nanoparticles, the morphology, structure and properties of the products were investigated. We proved that Fe3O4 and polyaniline were not mechanically mixed by XRD and FTIR.The effects of the amount of Fe3O4 on the magnetic property, thermal stability and microwave absorption property were studied,we discovered that when the amount of the Fe3O4 reached 4.76%, the nanoparticles had excellent microwave adsorption property, they were eager to be one kind of ideal microwave adsorption materials.