Self-diffusion coefficients obtained by the NMR spin-echo method are reported for water at temperatures below 0 °C and at pressures up to 350 MPa in the liquid region bounded by the ice I and ice III phases. The data are compared with other measurements in this region.
Data are reported for the intradiffusion coefficient of water (D w ) in aqueous solutions of 2-methyl-2-propanol (tert-butyl alcohol, TBA) as a function of pressure, temperature, and composition. In previous work (Harris and Newitt, J. Phys. Chem. B, 1998, 102, 8874), we have shown that for this system at mole fraction x TBA ∼ 0.025 and low temperatures, D w shows a maximum with increasing pressure to a greater relative extent than does the self-diffusion coefficient in pure water under the same conditions. It was concluded that this is consistent with the concept that the water is more structured in the TBA solution at this composition. Our present results confirm this at other concentrations below x TBA ∼ 0.06. This is also consistent with a previous, but unpublished, study of TBA intradiffusion by Woznyj, and the NMR relaxation and chemical shift results of Yoshida et al. (J. Chem. Phys., 1998, 108,1360. At higher concentrations, the normal behavior of a diminution of the diffusion coefficient with increasing pressure occurs. This is not consistent with ordering of hydration water suggested by certain models based on the presence of clathrate-like hydrates in solution.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.