Preparation of novel cobalt ferrite/chitosan grafted with graphene composite as effective adsorbents for mercury ions

In this study, a novel, amino-functionalized magnetic composite of CoFe2O4-chitosan-graphene (MCGS) had been successfully synthesized. The crystal phase, surface morphology and structure of the MCGS were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), zeta potential measurement, and Brunauer Emmett Teller (BET) surface area. The adsorptive characteristics of the MCGS which was intended for removal of Hg(II) from aqueous solutions were deeply studied. The results showed that the adsorption efficiency increased with the increasing of pH and reached the highest point at pH 7.0. The Hg(II) adsorption kinetics on MCGS was consistent with the pseudo second-order process. Langmuir and Freundlich isotherm models were employed to analyze the experimental data, and the Langmuir model was fitted better with a maximum adsorption capacity of 361.0 mg/g at pH 7.0 and 323 K. Thermodynamic studies illustrated that the adsorption process was endothermic and spontaneous. (C) 2014 Elsevier B.V. All rights reserved.