Preparation of Magnetically Separable Mesoporous Silica Microspheres with Open Pore Systems in Supercritical Carbon Dioxide

Magnetically separable mesoporous silica microspheres with open pore systems have been synthesized in supercritical carbon dioxide (SC-CO2). In the experiments, using the excellent transport properties of supercritical carbon dioxide, an acetone solution containing iron(III) acetylacetonate [Fe(acac)(3)] was easily infiltrated into the mesopores of the microspheres. After thermal decomposition, the Fe(acac)3 was easily transformed into Fe3O4 nanoparticles. A comparison experiment verified that the carrying effect of Fe(acac)(3) using SC-CO2 was better than that observed for the common method. The magnetic microspheres were characterized by transmission electron microscopy, energy-dispersive X-ray analysis (EDAX), powder X-ray diffraction, and nitrogen adsorption-desorption. The magnetically separable property of the microspheres was also tested.