[Adsorption properties of modified graphene for methylene blue removal from wastewater]

In this study, cetyltrimethylammonium bromide (CTAB) was chosen to modify graphene, which was applied to remove methylene blue (MB) from aqueous solutions. The characteristics of graphene and modified graphene were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), thermal gravimetric analyzer (TGA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The effects of factors including pH, contact time, temperature, and dosage on the adsorption properties of MB onto graphene and modified graphene were investigated. The results revealed that the addition of CTAB in preparation could obviously increase the specific surface area and improve the efficiency of removal. The adsorption processes were rapid within the first 15 min and reached equilibrium in about 120 min. The adsorption kinetics fitted well with the pseudo-second-order model. The optimal reaction temperature was 293 K, the optimal concentration of adsorbent dosage was 2 g x L(-1), and the initial pH value of the solution had little impact on the amount of adsorption. The adsorption capacity of MB on modified graphene inferred from the Langmuir model was 86.43 mg x g(-1) at 293 K, and the adsorption was an exothermic process.