Biocompatible G-Fe3O4/CA nanocomposites for the removal of Methylene Blue

Novel graphene based composites were prepared by encapsulating magnetic graphene (G-Fe3O4) into calcium alginate (CA). The obtained graphene-Fe3O4/CA composites were further applied as adsorbent for the removal of Methylene Blue (MB). Adsorption of MB onto G-Fe3O4/CA was investigated with respect to pH, adsorption time, initial MB concentration and temperature. Kinetics data and adsorption isotherm obtained at pH 7 were better fitted by pseudo-second-order kinetic model and by Langmuir isotherm, respectively. The values of activation parameters such as free energy (Delta G, -3.88 to -7.64.kJ mol(-1)), enthalpy (Delta H, 51.24 kJ mol(-1)) and entropy (Delta S, 188.06 J mol(-1) K-1) were calculated, indicating that the adsorption was spontaneous, favorable and an endothermic process in nature. The results suggest that the G-Fe3O4/CA composites are potential and suitable materials in the preconcentration of organic dyes from large volumes of wastewater. (C) 2015 Elsevier B.V. All rights reserved.