Solubility determination and model prediction of olive husk oil in supercritical carbon dioxide and cosolvents

Solubility of olive husk oil in supercritical carbon dioxide and cosolvents was determined using a dynamic flow method. The aim of the work was to determine the best processing conditions leading to maximum solubility and to obtain an empirical correlation to predict these data for further scale-up applications. The effect of pressure (15-35 MPa) and temperature (313-353 K) on the solubility showed that the solubility increases as the density increases. The cosolvent effect was studied in a range close to maximum solubility (30-35 MPa and 328-338 K). The cosolvents selected were methanol and ethanol in 1 and 5% (v/v) concentrations. In this case, the solubility enhancement was mainly caused by the formation of interactions between solute and cosolvent molecules. In the experimental range, the classical empirical models cannot be used properly because they are only based on the relation between the solubility and fluid density. A modification of the empirical correlations has been proposed introducing a new term that considers the cosolvent percentage. These modified correlations can be used to estimate olive husk oil solubilities when working using CO2 or CO2-cosolvent mixtures.