Density Measurements of CO₂-Expanded Liquids

Abstract

Novel experimental data of density for mixtures containing CO2 + ethanol, CO2 + ethyl lactate, CO2 + glycerol + ethanol, and CO2 + glycerol + ethyl lactate at low/moderate temperatures (308 and 323 K), pressures between 5 and 30 MPa, and high amounts of the organic solvent (molar fraction x = 0.5–0.9) are presented. The chosen organic solvents (ethanol, ethyl lactate, and glycerol) are green and applicable in food industry and present different polarizabilities. The density of CO2 + ethanol increased with the increment in the molar fraction of CO2, and the opposite was observed for the mixtures of CO2 + ethyl lactate. By adding a small amount of glycerol to the mixture of CO2 + ethanol and CO2 + ethyl lactate, it was possible to increase the density even a little further. The experimental data of density were well-correlated using the Peng–Robinson equation of state (PR-EOS) combined with Péneloux volume translation.