Fabrication of Fe3O4/SiO2 core/shell nanoparticles attached to graphene oxide and its use as an adsorbent

Amino-functionalized Fe3O4/SiO2 core/shell nanoparticles were synthesized by reacting Fe3O4 nanoparticles with tetraethyl orthosilicate and (3-aminopropyl) triethoxysilane to introduce amino groups on the surface. The amino groups on the Fe3O4/SiO2 were reacted with the carboxylic groups of graphene oxide (GO) with the aid of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinnimide to form Fe3O4/SiO2-GO nanoparticles. The structural, surface, and magnetic characteristics of the material were investigated by scanning and transmission electron microscopy, energy-dispersive X-ray spectrometry, powder X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Adsorption equilibrium and kinetics of methylene blue on the Fe3O4/SiO2-GO were studied in a batch system. The maximum adsorption capacities were found to be 97.0, 102.6, and 111.1 mg g(-1) at 25, 45, and 60 degrees C, respectively. A second-order kinetic equation could best describe the sorption kinetics. Thermodynamic parameters indicated that the adsorption of methylene blue onto the material was thermodynamically feasible and could occur spontaneously. (C) 2012 Elsevier Inc. All rights reserved.