Solubility of Squalene, Oleic Acid, Soya Oil, and Deep Sea Shark Liver Oil in Subcritical R134a from 303 to 353 K

Abstract

The solubilities of lipids typically found in marine oils and seed oil refining byproducts were measured in subcritical R134a to determine whether R134a could be a viable, low-pressure alternative to supercritical CO2. The solubilities of squalene, oleic acid, soya oil, and deep sea shark liver oil in subcritical R134a were measured in a countercurrent packed column apparatus over the temperature range 303 to 353 K at 60 bar. Solubility measurements were also made over the pressure range 40−200 bar at 343 K for shark liver oil and oleic acid. The solubilities of all solutes in R134a were low, ranging from 0.8 to 10 g of solute per kg of solvent. The solubilities increased almost linearly with increasing temperature at fixed pressure and increased logarithmically with increasing pressure at fixed temperature. The measurements show that R134a can be used as an alternative to supercritical CO2. The strong temperature dependence of the solubility allows for two-stage fractionation of extracts. Solubility as a function of individual solute type increased with decreasing polarity and decreasing molecular weight. The fractionation of deep sea shark liver oil and technical-grade oleic acid was observed in the solubility determinations. Lower-molecular-weight components were concentrated in the extract (R134a-rich phase), and high-molecular-weight components in the raffinate (lipid-rich phase). A linear solvation energy relationship approach was used to correlate the enhancement factors of the solutes as a function of the solvent polarity/dipolarizability factor. Linear relationships were obtained, but the dependence of the enhancement factor on other solute−solvent parameters could not be determined.