Correlation of Solubilities and Entrainer Effects for Fatty Acids and Higher Alcohols in Supercritical Carbon Dioxide Using SRK Equation of State with Association Model.

Abstract

Solubilities of fatty acids (myristic acid, palmitic acid and stearic acid) and higher alcohols (cetyl alcohol, stearyl alcohol and arachidyl alcohol) in supercritical CO2, and the entrainer effect (ethanol or octane) on their solubilities, are correlated by the Soave-Redlich-Kwong equation of state with an association model. It is assumed that the system consists of supercritical CO2, solute monomer, solute dimer, hydrogen bonding species between solute monomer and entrainer, and entrainer. The mole fractions of these species are determined by the equilibrium constants for dimerization of palmitic acid, and those for hydrogen bonding species between palmitic acid and ethanol obtained from FTIR spectroscopic study. The calculated results agreed with the experimental data.