Density and Volumetric Properties of Aqueous Solutions of Trimethylamine<i>N</i>-Oxide in the Temperature Range from (278.15 to 323.15) K and at Pressures up to 100 MPa

Abstract

Densities of aqueous solutions of trimethylamine N-oxide (TMAO) were measured over the concentration range (0.0875 to 4.3251) mol·kg–1 at temperatures (278.15, 288.15, 298.15, 308.15, and 323.15) K and pressures (0.101, 10, 25, 50, 75, and 100) MPa. Volumetric properties such as apparent molar volume of TMAO, Vϕ,2, molar isothermal compression, KT,m, molar isobaric expansion, EP,m, and internal pressure, Pint, of its aqueous solutions were calculated depending on concentration, temperature, and pressure. The volumetric partial properties of TMAO at infinite dilution in water (V2∞, KT,2∞, and EP,2∞) were also determined. The results were discussed from the standpoint of solute–solute and solute–solvent interactions.