Synthesis of monodisperse Fe3O4@silica core-shell microspheres and their application for removal of heavy metal ions from water

Monodisperse Fe3O4@silica core-shell microspheres have been successfully prepared by using a two step method. Due to their exceptional properties, these composite microspheres can be removed conveniently from water via an external magnet. These composite microspheres can be applied to remove heavy metal ions from industrial wastewater because the surface of the microspheres is covered with SiO2, and the SiO2 is inactive and can adsorb heavy metal ions (such as Hg2+, Pb2+). Furthermore, the interaction between SiO2 and heavy metal ions is reversible, which means that the adsorbed ions can be removed from SiO2 in weak acidic deionized water with the assistance of ultrasound radiation. It is noteworthy that the adsorption ability of the composite microspheres is so strong that any further modification of the composite microspheres is unnecessary. On the basis of the above points, we consider that the synthesized Fe3O4@silica composite microspheres can be used as a useful recyclable tool for heavy metal ion removal. This work provides a potential and unique technique for heavy metal ion removal from industrial wastewater. (c) 2009 Elsevier B.V. All rights reserved.