Adsorption of Pb(II) and Hg(II) from aqueous solution using magnetic CoFe2O4-reduced graphene oxide

Magnetic cobalt ferrite (CoFe2O4)-reduced graphene oxide (rGO) nanocomposites (CoFe2O4-rGO) were developed as an adsorbent to remove Pb(II) and Hg(II) from aqueous solution. The CoFe2O4-rGO was prepared by a facile approach and characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area and Zeta potential measurement. In this work, contact time, adsorbent dose, and solution pH temperature were optimized. The sorption kinetics and isotherm model fitting studies, demonstrated that data fit well to pseudo-second order kinetics and Langmuir isotherm models. The highest adsorption equilibrium for Pb(II) were 299.4 mg/g at pH of 5.3 and 25 degrees C; while for Hg(II) were 157.9 mg/g at pH of 4.6 and 25 degrees C. Due to magnetic property, CoFe2O4-rGO could be simply recovered from water by magnetic separations at low magnetic field within 2 min. (C) 2013 Elsevier B.V. All rights reserved.