High pressure vapor-liquid equilibrium for the ternary system ethanol/(±)-menthol/carbon dioxide

In this work the phase behavior of the ternary system ethanol/(±)- menthol/CO₂ was studied at the temperatures of 313 and 323 K, in the pressure range 8-10 MPa. Experiments were performed using a high pressure phase equilibrium apparatus with a visual cell. CO₂ is more selective toward ethanol, separation factors ranging from 1.6 to 7.6 at the conditions tested. The pTxy data obtained were correlated with the Peng-Robinson equation of state combined with the Mathias-Klotz-Prausnitz mixing rule. The model gave a good fitting to the data, with a total average absolute deviation of 3.7%, and was able to predict the occurrence of a three-phase region observed experimentally at 313 K and 9 MPa.