(387a) Interfacial Aqueous Systems: Ion-Ion Correlations and the Electric Double Layer

Aqueous electrolyte solutions at interfaces have generated, and continue to generate, significant research interest due to their importance in numerous phenomena for a wide range of applications. Molecular dynamics simulations have been employed to study structural and dynamic properties of aqueous electrolyte solutions near free standing silica-based surfaces. This study focuses on the properties of various monovalent (Cl-, Na+, Cs+) and divalent ions (S2-, Ca2+, Sr2+) within a few molecular layers from solid-liquid interface. A wide range of ionic strengths was considered in our simulations to investigate the effect on the structure, dynamic properties and accumulation of ions at the solid interface. Two crystallographic faces of the cristobalite crystal with different degrees of hydroxylation were employed to assess the effect of surface roughness and charge density on the properties of interest. The SPC/E model was used to model water-water interactions. Density profiles, radial distribution functions, in-plane density distribution, residence time, and diffusion coefficients were calculated to study the effect of surface properties on the characteristics of confined water and on the formation of the electric double layer.