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