Preparation and Adsorption Properties of Albino Modified Magnetic Mesoporous Microsphere Fe3O4@SiO2@mSiO2

The SiO2 encapsulated Fe3O4 composite magnetic microsphere was synthesized by a modified Stober method with Fe3O4 nanoparticles as cores. The structures and properties of the composite were characterized by XRD, SEM, TEM, N-2 absorption-desorption, FTIR and VSM. The results showed that the as-prepared magnetic microspheres exhibited a spherical shape and uniform particle size distribution. This material possessed a BET surface area of 413 m(2).g(-1) and saturation magnetization of 68.93 emu.g(-1), respectively. The particle morphology became more uniform with the increase of TEOS volumes when silica shell became thicker. The saturation magnetization of the nanocomposite particles decrease with the thickness of the silica shell increasing, the coercive force of particles was almost unchanged, and remained favorable to superparamagnetism. Based on the composite magnetic microsphere, the new magnetic nano-adsorbent Fe3O4@SiO2@mSiO(2)-NH2 was fabricated by coating silica from a covalent binding of amino (-NH2) onto the surface of Fe3O4@SiO2@mSiO(2) microsphere. And the adsorption properties of the adsorbent for Cr(VI) ions were investigated. The study on kinetics of CAD showed that the adsorption reaction could be considered as the pseudo-second-order kinetic model. The adsorption capability was significantly affected by the distributions of Cr(VI) species and -NH2. The adsorption mechanisms of Cr(Vl) including both ion exchange and electrostatic gravitation were also discussed.