1H NMR Diffusion Studies of Water Self-Diffusion in Supercooled Aqueous Sodium Chloride Solutions

The physical properties of aqueous sodium chloride solutions have been studied theoretically, but so far no experimental diffusion data have been obtained under supercooled conditions. Here the results of H-1 NMR translational diffusion measurements of water in sodium chloride solutions in the temperature range 230 to 300 K and sodium chloride concentrations up to 4.2 mol/kg are presented. It was found that the diffusion data were well-described by the Vogel-Tamman-Fulcher relationship with concentration-dependent parameters D-0, B, and T-0. The results indicate that under supercooled conditions the influence of sodium chloride on water diffusion is much smaller than predicted by molecular dynamics simulations.