Study on micromechanical mechanism of ionic environment affecting adsorption behavior between graphene and benzene

As the ion concentration increased, the adsorption of benzene on graphene was initially slightly enhanced, but then significantly inhibited. At the same ion concentration, higher ionic valence was more favorable to adsorption than lower ionic valence. Comparative analysis demonstrated that ion concentration exerts a greater influence on the adsorption behavior than ionic valence. • Single-bond forces at different ion environment were obtained by AFM experiments. • Ions will change ESP charge and preempt adsorption sites on the graphene surface. • Ion concentration first promoted and then inhibited graphene adsorbing benzene. • Higher ion valence was more favorable to adsorption than lower ion valence. • The influence of ion concentration on adsorption is greater than that of ion valence. Graphene, an adsorbent material with excellent recyclability and large specific surface area, can effectively adsorb or desorb benzene-containing pollutant molecules in wastewater. In this study, we employed a combination of theoretical analysis, molecular dynamics simulations and atomic force microscopy experiments to elucidate the micromechanical mechanisms by which the ionic environment affects the π-π interactions between benzene and graphene. The results reveal that as the ion concentration increases, the adsorption behavior of graphene toward benzene rings is initially slightly enhanced but subsequently significantly inhibited. At the same ion concentration, higher ion valence promotes adsorption more effectively than lower ion valence. Comparative analysis demonstrates that ion concentration exerts a stronger influence on adsorption or desorption behavior than ion valence. The two primary mechanisms driving these phenomena are the impact of ions on the electrostatic potential charge distribution across the graphene surface and their competitive occupation of adsorption sites on graphene. These findings suggest that the amount of aromatic pollutant in wastewater can be precisely controlled by modulating the ionic environment. This study underscores graphene’s potential as a highly recyclable adsorbent material with significant promise for practical applications.