Adsorption of metal ions on graphene sheet for applications in environmental sensing and wastewater treatment

•Interaction of biographene with metal ions was studied experimentally by zeta potential titrations and absorption spectral data.•Metal ion binding to graphene nanosheets was computationally evaluated by density functional theory.•Comparison of the experimental data of biographene with computational data show that metal binding to biographene is dominated by charge transfer interactions between the graphene electron cloud and the metal ion.•Metal ion binding to graphene is dominated by electronegativity and ion charge density.