Enhanced Adsorption of Methylene Blue on Graphene Oxide by Tuning the Oxidation Degree of Graphene Oxide

Enhanced Adsorption of Methylene Blue on Graphene Oxide by Tuning the Oxidation Degree of Graphene Oxide

Graphene oxides (GOs) with different oxidation degrees were prepared and characterized. The adsorption behavior was studied to clarify the correlation between the adsorption ability and the oxidation degree of GO by using methylene blue (MB) as a model compound. It was observed that the adsorption of MB on the oxidized graphene oxides (OGOs) followed the Langmuir isotherm model and that the adsorption kinetics fitted the pseudo second-order model. With increasing the oxidation degree of GO, the maximum adsorption capacity was initially increased and then decreased. By tuning the oxidation degree of GO, the maximum adsorption capacity at 298 K could be increased from 671.1 to 1449.3 mg g-1 by a factor of more than 200%. The significant increase of the adsorption capacity on OGO was attributed to the increased numbers of carboxyl groups on the surface of OGO, which enhanced electrostatic attractions between MB and the adsorbent.