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, V ϕ,2, molar isothermal compression, K T,m, molar isobaric expansion, E P,m, and internal pressure, P int, of its aqueous solutions were calculated depending on concentration, temperature, and pressure. The volumetric partial properties of TMAO at infinite dilution in water ( V 2 ∞, K T,2 ∞, and E P,2 ∞ ) were also determined. The results were discussed from the standpoint of solute–solute and solute–solvent interactions.