Improved synthesis of graphene/β-cyclodextrin composite for highly efficient dye adsorption and removal

Graphene/beta-cyclodextrin (GNS/β-CD) composite was prepared by an improved method, and its adsorption performance for phenolphthalein was investigated. This improved method could enhance the stability of GNS/β-CD due to the covalent bond link between β-CD and GNS, and achieve the synergistic adsorption of organic dye compound on β-CD and GNS in GNS/β-CD composite because of the remove of some oxygen-containing groups on the surface of GO in GNS/β-CD. The adsorption of Php on GNS/β-CD was hardly influenced by ionic strength. The adsorption equilibrium was achieved within 20 min. The adsorption kinetics followed the pseudo-second-order model and the adsorption isotherms were well fitted by the Langmuir model. Thermodynamic analysis suggested that the adsorption of Php on GNS/β-CD was spontaneous and exothermic. The GNS/β-CD composite could be regenerated several times based on its adsorption/desorption cycles, with a slight loss in its adsorption. For the actual dyes, the saturated adsorption capacities of methyl blue, methyl orange and basic fuchsin on GNS/β-CD were 580.4, 328.2 and 425.8 mg/g, respectively, higher than many currently reported. The obtained results indicated that GNS/β-CD could be rapid and high effective adsorbent to remove dyes from water.