Fabrication of hollow spheres self-assembled by magnetic Co nanoparticles

A core-shell structure of stable cobalt (Co) nanosized particles (NPs) was synthesized, in which the core was hcp Co and the shell was amorphous Co. An anionic surfactant, sodium bis-2-ethylhexyl-sulfosuccinate (AOT), was used as a template. Hollow sphere-like structures were obtained. These structures were self-assembled by the core-shell structure of magnetic Co NPs. Magnetic properties of the sample were studied by using VSM. A novel result was obtained in which these hollow sphere-like structures with small surface areas exhibited excellent water treatment performance for organic dyes, such as methyl orange. The maximum adsorption capacity was calculated to be 193.3 mg/g, which is higher than that of the samples reported in our previous study with higher BET surface area. (C) 2012 Elsevier B.V. All rights reserved.