▎ 摘　　要

In this study, an effective bio-adsorbent of graphene immobilized cross-linked chitosan (GCCT) beads were successfully prepared by entrapping graphene in cross-linked chitosan. The adsorbents were characterized by scanning electron microscope, Fourier infrared spectroscopy and N-2 adsorption-desorption isotherms. Batch adsorption experiments were performed to remove cationic dye, methylene blue (MB), in aqueous solution using GCCT beads. The effect of initial MB concentration (10-90 mg/L) and temperature (25 degrees C-65 degrees C) on the adsorption removal of MB was evaluated. The adsorption kinetics, isotherm, mechanism and thermodynamics were also discussed. The results showed that the graphene immobilization over the chitosan significantly improved the specific surface area of chitosan beads. Thus, the GCCT beads presented a remarkable enhancement of adsorption capacity for the removal of MB from the aqueous solution. The kinetics of adsorption of MB followed the pseudo-second kinetics equation, and the equilibrium data were better analyzed by Freundlich isotherm model. At the temperature of 65 degrees C, the Freundlich maximum multilayer adsorption capacity of GCCT beads for 90 mg/L MB was 7.64 mg/g. Adsorption diffusion model stated that the present adsorption was not only controlled by the intraparticle diffusion. The thermodynamic parameters showed that the present adsorption was a spontaneous and endothermic process. Overall, the GCCT beads have proved a promising adsorbent for removal of dyes from aqueous solution.