Solubility of fatty acids in supercritical carbon dioxide

Abstract

The solubilities of lauric, linoleic, myristic, oleic, palmitic and stearic acid in supercritical carbon dioxide (SC‐CO2) at different pressures and temperatures were measured. The solubility values obtained in this work were compared with previously published data, and possible causes for observed discrepancies were discussed. The solubilities of the six fatty acids were modeled by Chrastil’s equation, and estimated model parameters were used to plot the solubility isotherms of fatty acids at 313, 323 and 333°K (40, 50 and 60°C) as a function of SC‐CO2 density. The comparison of solubility isotherms of fatty acids and vegetable oil suggests that separation of fatty acids from triglycerides might be possible by using SC‐CO2 at densities less than 700 kg/m3. From the effect of temperature on fatty‐acid and vegetable‐oil solubility, it seems that the extraction yield could be increased without sacrificing the selectivity of SC‐CO2 for fatty acids by choosing a higher operating temperature. The data also suggest that fractionation of certain fatty acids might be possible by manipulating the processing conditions. Given the values of the constants, Chrastil’s equation could serve as a guideline for choosing appropriate processing conditions and predicting the effect of pressure and temperature of SC‐CO2 on solute solubility.