Molecular dynamics simulations of the structure and dynamics of aqueous NaCl solutions on extended quartz surfaces

Abstract

Corrosion of silica surfaces by solutions of sodium chloride (NaCl) occurs often; the aggregation of ions and water molecules on the silica surface represents the first step. In this work, the structure and dynamics of ions and water molecules at the silica-solution interface were studied by molecular dynamics simulations. The influence of different NaCl concentrations was explored. With an increase in the NaCl concentration, the hydrogen bonds among water molecules are broken gradually. Meanwhile, more and more water molecules were involved in ionic hydration. Furthermore, the aggregation of ions observed at the silica-liquid interface layer was due to ion hydration. At high NaCl concentrations, self-diffusion of Na+ and Cl− slowed due to the enhanced Coulombic effect and fewer water molecules surrounding an ion during ionic hydration. This work provides a fundamental understanding of the salt solution behavior on a silica surface.