Adsorption of methylene blue from aqueous solution by graphene

Graphene was prepared using a modified Hummers’ method. The physico-chemical properties of graphene were characterized by TEM, BET specific surface area, FTIR, Raman and XRD measurements. The effect factors including pH, contact time, temperature and dosage on the adsorption properties of methylene blue onto graphene were investigated. The experimental data of isotherm followed the Langmuir isotherm model better than the Freundlich model. The maximum adsorption capacity obtained from Langmuir isotherm equation at 293 K was 153.85 mg/g, indicating graphene is a good adsorbent for the adsorption of MB. The kinetic study illustrated that the adsorption of methylene blue onto graphene fit the pseudo second-order model. The thermodynamic parameters indicated that the adsorption of methylene blue onto graphene was an endothermic and spontaneous process.

This figure shows the effect of temperature on the adsorption of methylene blue onto graphene. The methylene blue adsorption capacities increase from153.85 to 204.08 mg/g with the increase in temperature from 293 to 333 K. The results demonstrate that the adsorption of MB onto graphene is an endothermic process.Figure optionsDownload as PowerPoint slideHighlights
► Graphene is a good adsorbent for the adsorption of methylene blue.
► Graphene prepared in this work was characterized by TEM, BET, FTIR and Raman.
► The removal efficiency of methylene blue was high even at a low pH.
► The adsorption of MB onto graphene was an endothermic and spontaneous process.