Phase behavior of β-d galactose pentaacetate–carbon dioxide binary system

Phase behavior of β-d galactose pentaacetate–carbon dioxide binary system is investigated by dew-point and bubble-point measurements conducted in a high pressure variable volume sapphire cell. The phase envelope for solutions of β-d galactose pentaacetate in supercritical CO2 is obtained for β-d galactose pentaacetate concentrations between 2 and 26 wt%, and for the temperature range of 308–323 K. The system exhibits lower critical solution temperature (LCST) behavior and high solubility of β-d galactose pentaacetate is observed. The densities of the system are also measured, and liquid-like densities (near 1 g/cm3) are observed for single-phase solutions of β-d galactose pentaacetate in supercritical CO2 at concentrations of 18 wt% and higher. Viscosity is measured for solutions of 18 and 25 wt% β-d galactose pentaacetate in the single-phase region at 313 K and 17 MPa and the viscosity values, 0.095 and 0.103 cp, respectively, are similar in magnitude to the viscosity of pure carbon dioxide.