Density Measurements of CO₂-Expanded Liquids

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.