Thermodynamic modeling of the vapor–liquid equilibrium of the water/ethanol/CO2 system

The Cubic Plus Association Equation of State (CPA EoS) developed in this laboratory is applied here in the correlation of the binary vapor–liquid equilibrium (VLE) and in the prediction of the ternary VLE of the water/ethanol/carbon dioxide system at various temperatures and pressures. Carbon dioxide is treated in three different ways: (a) as a non-associating molecule, (b) as an only cross-associating molecule (not self-associating), and (c) as a both self- and cross-associating molecule. The results obtained from the CPA EoS are in good agreement with the experimental data for the binary and ternary systems, when carbon dioxide is considered either as a self-associating or only a cross-associating molecule with the first approach to give better results. Furthermore, the comparison with the results obtained from SAFT EoS indicates that CPA performs overall better than SAFT.