High-pressure phase equilibria and thermodynamic modelling for the binary systems CO2+lemon oil and C2H6+lemon oil

The solubility of ethane and carbon dioxide in lemon oil at elevated pressures has been measured using a variable volume cell, in the temperature range of 298–308 and 303–313 K, respectively, and at pressures from 0.44 to 8.75 MPa. At the studied concentration levels no liquid–liquid immiscibility was observed. The results are compared with data from the literature. The molar densities of the saturated liquid mixtures are also reported. The Soave–Redlich–Kwong equation of state was used to fit experimental vapor–liquid equilibria of near critical light component — lemon oil mixtures. An appropriate representation of the experimental data was obtained by using a binary interaction parameter in the combining rule for the cross energy parameter aij. The application of a quadratic mixing rule for the co-volume b with a binary interaction coefficient lij does not improve greatly the performance of the model. It seems that the unlike intermolecular effects are more important that the size-ordering effects, for both mixtures CO2–lemon oil and ethane–lemon oil.