Supercritical carbon dioxide fractionation of the model mixture squalene/oleic acid in a membrane contactor

Six different membranes were tested at 18.0 MPa and 313 K for their performance to fractionate a model mixture of squalene/oleic acid with supercritical carbon dioxide. A significant enrichment of squalene in the permeate side was achieved with a 10 μm-coating layer polydimethyl siloxane (PDMS) membrane at the tested conditions although with the drawback of a lower total permeate flux. Additional fractionation experiments of the same model mixture were carried out in a countercurrent packed column at 18.0 MPa of pressure and 313 and 323 K of temperature. At a solvent-to-feed mass flow ratio of ca. 40 an extraction efficiency of 88% of the total mass of squalene fed to the column was obtained at 18.0 MPa/313 K. The raffinate and extract streams obtained at these conditions had a squalene content of 10 and 63.5 wt%, respectively. An optimized combination of supercritical extraction and membrane separation could be used to increase the purity of the extract stream in squalene.