Correlation of solubilities and entrainer effects for fatty acids and higher alcohols in supercritical carbon dioxide using SRK equation of state with association model

The solubilities of fatty acids, i.e., myristic acid, palmitic acid, and stearic acid, and higher alcohols, e.g., cetyl alcohol, arachidyl alcohol, and stearyl alcohol, in supercritical CO₂, and the entrainer effect (ethanol or octane) on their solubilities, were correlated by the Soave-Redlich-Kwong EOS with an association model. The system was assumed to consist of supercritical CO₂, solute monomer, solute dimer, hydrogen bonding species between solute monomer and entrainer, and entrainer. The mole fractions of these species were obtained by the equilibrium constants for dimerization of palmitic acid, and those for hydrogen bonding species between palmitic acid and ethanol determined from FTIR spectroscopic study. The computed results agreed with the experimental data.