Controllable Fabrication Of Cobalt Ferrtie Magnetic Hollow Spheres And Studies On Their Applications

In the present work,monodispersed magnetic hollow spheres are prepared using a template-assisted method,which is facile and eco-friendly route for the fabrication of magnetic hollow spheres to meet different demands.In addition,the adsorption property of magnetic hollow spheres for bovine serum albumin and their extended applications in photocatalysis are also primarily investigated.The main content and novelty of this thesis are detailed as follows:Monodispersed cobalt ferrite magnetic hollow spheres are prepared by a simple co-precipitation of ferric chloride and cobalt nitrate over polystyrene spheres in the presence of aqueous NaOH solution followed calcinations.XRD,FT-IR,TG-DTA,SEM,TEM,BET and VSM techniques are used to investigate the influences of template sizes and pH conditions upon composition,magnetic properties and morphology of the magnetic hollow spheres.The results show that the pH value is a key point in regulating the composition of magnetic hollow spheres.The as-prepared magnetic hollow spheres,whose saturation magnetization values fall in 22.7-43.8 emu/g,are mainly composed of cobalt ferrite phase.Moreover,it is firstly observed that the cobalt ferrite nanoparticles constructing the hollow spheres wall present prominently different shape and stacking mode depending on the template size.The adsorption properties of the cobalt ferrite magnetic hollow spheres with different sizes for bovine serum albumin(BSA) are firstly investigated.The results show that the adsorption amount of bovine serum albumin on magnetic hollow spheres is 75.0-104.7mg/g.The maxium adsorption amount is observed on the middle-sized magnetic hollow sphere(～600nm),which is probably originated from the matchable size of the pore diameters of the magnetic hollow spheres and the BSA molecules.Using magnetic hollow spheres as substrates,photoactive titania are coated on their surface via a sol-gel method,in order to fabricate the photoactive titania modified magnetic hollow spheres.The obtained titania modified magnetic hollow spheres are mainly composed of anatase and cobalt ferrite,showing ferromagnetic,and considerable photocatalytic degradation activity for methyl orange(k = 1.5x10^-3 min^-1, which is comparable with that of the solid core-shell structured nanoparticles).Taking into account the low density and good dispersion in water,it can be expected that magnetic hollow spheres may have greater potential in applications.