Molecular simulation of adsorption of methylene blue and rhodamine B on graphene and graphene oxide for water purification

Adsorption of methylene blue (MB) and rhodamine B (RB) on pristine graphene and graphene oxide (GO) were investigated using molecular dynamics (MD) and Monte Carlo adsorption locator simulations. To study the nature of various interactions involved for adsorption of dye molecules on graphene oxide sheet, GO with different oxidation densities were simulated. Equilibrium configurations obtained from MD simulations and Monte Carlo adsorption locator confirmed the predominant interactions are π-πelectron coupling and electrostatic. MB molecule prefers to have configurations that facilitates the π-πinteraction, which is evident from the planar orientation of MB towards GO with less oxidation sites. RB prefers to attach at the highly oxidized sites of the GO sheet. The adsorption mechanism of dye molecules on graphene and GO surfaces explored using MD and Monte Carlo adsorption locator will assist in designing potential water purifying membranes.