| Magnetite(Fe3O4)nanoparticles were widely applied in applications including information memory,signal sensor,microwave absorption and biomedicine due to their high chemical stability and excellent biocompatibility and magnetic proporty.Magnetite as a functional material with magnetic,has been widely used,and the magnetite can be covered with other materials to form nano magnetite particles.The nanocomposite balls exhibit more powerful applications,and play an irreplaceable role in chemistry and biomedicine.Therefore,the properties in the visible light photocatalytic degradation of organic wastewater and removal of organic contaminants have attracted great attention of researchers.Currently,researchers have successfully synthesized of Fe3O4 nanomaterials with different morphologies and found that the photocatalytic property of nanomaterials coated with TiO2 film is improved greatly through hydrothermal method.This paper synthesized Fe3O4 particles with good monodisperse,high crystallinity,a high saturation magnetization and low coercivity,through solvothermal method.And reveals that surface modification on these nanomaterials have important theoretical and practical value for improving its visible light photocatalytic properties.The main idea is as follows:(1)In this study,the Fe3O4 nanoclusters were synthesized using a solvothermal method with FeCl3·6H2O as iron precursor,ethylene glycol as solvent and reducing agent,anhydrous sodium acetate as ligand salt,and sodium citrate as stabilizing agent.The prepared Fe3O4 nano-clusters were characterized by X-ray powder diffraction(XRD),field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM)and vibrating sample magnetometer(VSM).The results showed that Fe3O4 nano-clusters are uniform spheres with 268 nm in diameter and the distribution of size is very narrow.They displayed a typical super para-magnetism at room temperature and the saturation magnetizaition intensity is 65 A-m2/kg.(2)The Fe3O4@TiO2 magnetic composite microsphere with core-shell structure was synthesized with Fe3O4 nanoparticles as cores and TiO2 as its outer layer which were synthesized using a Sol-gel method.Then,the samples were modified by hydrothermal method to obtain the mesoporous composite microspheres with strong magnetism and excellent photocatalytic efficiency.The structure and morphology of the prepared Fe3O4@mTiO2 magnetic composite microspheres were characterized to analyze.The photocatalytic property was tested under xenon lamp irradiation using MB degradation as the model reaction,the influence of heat treatment on light catalyst were analyzed.The results showed that the prepared Fe3O4@TiO2 magnetic microspheres possess spherical shape,uniform distribution of particle size,and smooth crustose TiO2 film.Three shape Fe3O4 typical diffraction peaks and TiO2 anatase type diffraction peak were observed in the XRD patterns of Fe3O4@mTiO2 magnetic microspheres,which indicated that the coating process did not destroy the crystal structure of Fe3O4.The saturation magnetizaition intensity of Fe3O4@TiO2 without overheating treatment is 33 A·m2/kg,and that of Fe3O4@mTiO2 after heat treatment is increased to 55 A_m2/kg.In addition,photocatalytic results showed that Fe3O4@TiO2 prepared by Sol-gel method possess the highest photocatalytic activity.The degradation rate of MB reaches 79%,is higher than that of the pure TiO2.At the same time,the Fe3O4@TiO2 prepared by Sol-gel possess stronger stability,higher cycle efficiency and recovery rate which make it more convenient to recyed and thus meets well the demands of pratical applications in environmental protection.(3)The Fe3O4@SiO2 magnetic core-shell composite microspheres were synthesized by the hydrolysis of silicon alkoxides catalyzed by ammonia using modified Stober method in ethanol/water solution,in which Fe3O4 nanoparticles acted as cores which were synthesized using a solvothermal method and tetraethyl orthosilicate(TEOS)served as precursor.The morphology,structure and magnetic properties of Fe3O4@SiO2 magnetic composite microspheres were characterized and tested.The results showed that the as-prepared Fe3O4@SiO2 magnetic microspheres exhibited spherical shape and uniform particle size distribution.Moreover,SiO2 shells were round and smooth and their thickness was round 4O-70nm.XRD pattern showed Fe3O4@SiO2 magnetic microspheres possessed sharp Fe3O4 characteristic diffraction peaks,indicating that the coating process did not destroy the crystal structure of Fe3O4.They also displayed discrete diffraction peaks of Fe3O4 and typical super para-magnetism at room temperature and the specific saturation magnetization intensity was 30A·m2/kg. |
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