Phase equilibrium of the system supercritical carbon dioxide–lemon essential oil: New experimental data and thermodynamic modelling

New experimental phase equilibrium data on the system supercritical CO2–lemon oil are provided at 50 °C and 70 °C, for pressures in the range 8.6–10.1 MPa and 9.7–13.5 MPa, respectively. Additional phase equilibrium data on the binary sub-system CO2–limonene are also provided. The measurements were carried out in a double-chamber isothermal apparatus of 340 cm3. Both the mass fraction of CO2 in the two phases and in the overall system was measured. The composition of the two phases on CO2-free basis was also measured. A thermodynamic model based on the Peng–Robinson equation of state was developed in order to represent the behaviour of the system supercritical CO2–lemon oil. The model uses only regression parameters calculated from binary sub-systems, thus being predictive with respect to the multicomponent mixture. A good representation of the phase equilibrium data is obtained with the proposed thermodynamic model.