High adsorption of methylene blue from water onto graphenic materials: Effect of degree of graphitization and analysis of kinetic models

摘要

The removal by adsorption of methylene blue dye from water using two-dimensional (2D) (graphene oxide and reduced graphene oxide) and three-dimensional (3D) (graphite and graphite oxide) carbon structures was studied. Two graphites with different degrees of graphitization were used to evaluate the significance of the carbon structural order in the adsorption efficiency, and therefore, the economic repercussions, because the degree of graphitization is related with the cost. Graphene oxides showed the best performance in methylene blue adsorption, with a removal of around 90%. The adsorption process was strongly influenced by the surface oxygenated groups, and electrostatic interaction was the main mechanism of adsorption. The degree of graphitization of the precursor does not have a strong influence on the adsorption results of methylene blue. Thus, graphene oxide with a lower degree of graphitization represents an economical and efficient adsorbent for the removal of methylene blue from water. The kinetic study was realized in pseudo-first order, pseudo-second order, and Elovich kinetic models in their linear and non-linear forms. According to the determination coefficient and the standard deviation, the experimental data were best fitted to the Elovich model in its non-linear form.