Fabrication of graphene oxide/bentonite composites with excellent adsorption performances for toluidine blue removal from aqueous solution

Abstract

The graphene oxide/bentonite (BG) composites are prepared through graphene oxide (GO) nanosheets successfully intercalated into acid-treated bentonite interlayer and deposited onto external surface. The BG composites exhibit a higher uptake capacity of toluidine blue (TB) dye from water solutions than normal bentonite owing to the synergistic effect between bentonite and GO. The as-prepared composites are characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and N2-sorption analysis. The process parameters affecting the adsorption behaviors such as initial pH, temperature, contact time and initial concentration of dye are systematically investigated. The Langmuir isotherm model fit well with the equilibrium adsorption isotherm data and the maximum adsorption capacity is 458.7 mg·g−1 at pH 8 for BG composites modified using 1% GO. The pseudo-second-order kinetic model well describes the adsorption process of TB onto BG composites. The TB adsorption on BG composites is mainly attributed to ion exchange, electrostatic interaction and intermolecular interactions. The outstanding adsorption performances of composites for the removal of TB dye from water demonstrate its significant potential for environmental applications.