Correlation of phase equilibria of liquid fatty acids and their esters in supercritical carbon dioxide

Binary phase equilibria of fatty acids and their methyl/ethyl esters in supercritical carbon dioxide were well-correlated using the Peng-Robinson equation of state with the functional form for alpha(T) proposed by Sheng and Lu. The substances investigated include five fatty acids (lauric, palmitic, oleic, Linoleic, and arachidic), five methyl esters (myristate, palmitate, stearate, oleate, and linoleate), and five ethyl esters (stearate, oleate, linoleate, eicosapentaenoate (EPA), and docosahexenoate (DHA)). Specific general constants were obtained in the alpha(T) function for the three families of compounds. In addition, the remaining coefficients were well-correlated in terms of the number of carbon atoms and the number of double bonds in the fatty acid portion of the compounds.