Fractionation of edible oil model mixtures by supercritical carbon dioxide in a packed column. Part I: Experimental results

The design of countercurrent packed columns operating under high-pressure conditions requires knowledge of their hydrodynamic and mass transfer behavior. A laboratory-scale continuous supercritical fluid extraction apparatus was developed with the purpose of obtaining data needed for such designs. The current work is part of a study to assess the feasibility of supercritical carbon dioxide in fractionating a mixture of squalene and methyl oleate. This mixture partly emulates the residues obtained from the olive oil refining process. Phase equilibrium data were previously measured to evaluate the best operating conditions. Here, we examine the continuous fractionation of two different feeds, with 40 and 70 wt % of squalene, under various extraction conditions. An extraction yield as high as 90 wt % of squalene in the raffinate phase was achieved. The selectivity and extraction efficiency were determined as functions of the oil-to-carbon dioxide flow ratio as well as the reflux ratio. In a subsequent paper (Part II), the measured hold-up and mass transfer coefficients will be compared with mass transfer correlations from the literature, and a model will be developed.