Preparation and adsorption property of graphene oxide by using waste graphite from diamond synthesis industry

Abstract

Graphene oxides (GO) were prepared from waste graphite from diamond synthesis industry by using the modified Hummers method. The phase composition, microstructure, specific surface area and pore size distribution of the waste graphite and the as-prepared GO samples were characterized by X-ray diffraction, Fourier transformed infrared spectra, Ultraviolet visible spectroscopy, Raman spectroscopy, field-emission scanning electron microscopy and nitrogen adsorption-desorption tests. The adsorption property of GO to methylene blue (MB) was investigated. The results show that the as-prepared GO has few layers, specific surface area of 116.6 m2 g−1 and a little different structure from those prepared by using natural flake graphite. It exhibited excellent adsorption performance in MB aqueous solution. Adsorption time, GO dosage, initial concentration, and pH value of MB aqueous solution play important roles but the solution temperature had a little effect on the removal rate of MB and the adsorption capacity of GO. Under the condition of a GO dosage of 5.7 mg, room temperature, initial concentration of 12 mg L−1, pH value of 6.5 and adsorption for 40 min, the removal rate of MB and the adsorption capacity of GO reached 96.05% and 379.89 mg g−1, respectively. The adsorption process of MB onto GO met well with a pseudo-second-order kinetic model and Langmuir adsorption isotherm model. The adsorption reaction was spontaneous and purely based on endothermic process.