Fractionation of Lipid Mixtures by Subcritical R134a in a Packed Column

Abstract

Deep-sea shark liver oil was fractionated by subcritical R134a in a pilot-scale continuous packed column with the aim of evaluating the potential of R134a as a near-critical solvent for extracting valuable substances from lipid mixtures. Fractionation was carried out at 6.0 MPa and in the temperature range of 333−353 K. The solvent-to-oil flow ratio was varied in the range 25−100, and its influence on the fractionation efficiency was evaluated. A high separation factor between squalene and the triglyceride fraction was achieved. The R134a solvent was regenerated in two consecutive separation vessels, held at the same pressure but different temperatures, which gave a relative enrichment in squalene content in the second separation product. A model mixture of oleic acid and squalene was also fractionated by subcritical R134a at 6.0 MPa and in the temperature range of 333−353 K. Minimal separation was achieved between these two compounds, which correlates with the almost identical solubilities of the two pure substances in subcritical R134a. Mass transfer models with different hydrodynamic considerations were used to model the shark liver oil fractionation behavior in the pilot-scale column. Both models overpredicted the mass transfer coefficients as compared with the experimental values. A model based on laminar film flow of the dispersed phase gave the closest agreement to the experimental mass transfer coefficients and holdups.