Removal of Pb(II) Ion Using PAMAM Dendrimer Grafted Graphene and Graphene Oxide Surfaces: A Molecular Dynamics Study

The dendrimer polyamidoamine (PAMAM) has been widely applied in environmental applications as adsorbents for wastewater treatment. In this work, molecular dynamics simulations are conducted to understand the effect of dendrimer grafted graphene and graphene oxide on the structural and dynamical properties of the Pb²⁺ ion. The adsorption capacity of the metal ion is improved significantly, over 60%, using carboxyl terminal groups of a dendrimer molecule grafted on a graphene oxide surface. We examine the self-diffusion coefficient and residence time of Pb²⁺ ion near graphene and graphene oxide surfaces grafted with PAMAM dendrimers using terminal groups, -COO^- and -OH. Further, the potential of mean force is analyzed to understand the role of different surface groups in enhancing the adsorption of the metal ion.