Phase equilibria for the carbon dioxide-ethanol system and the carbon dioxide-ethanol-water system were measured to provide the thermodynamic base for the extraction of ethanol from its aqueous solutions using near-critical carbon dioxide as solvent. The experiments were carried out at 283 K–298 K and 5–7 MPa, including extraction conditions and solvent-recovery conditions in a wide range of ethanol concentration.
An empirical mixing rule for the Helmholtz function with ternary as well as binary non-randomness parameters was proposed based on the density-dependent local composition concept. A correlation model was derived by a combination of the mixing rule with the Helmholtz function obtained from the Patel-Teja equation of state. The model successfully correlated the phase equilibria of the carbon dioxide-ethanol-water system.