Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

In this study experimental P T x y equilibrium data for four binary mixtures over a wide range of pressure (10.44 23.54MPa) were determined at 313K and 333 K. Liquid and vapor densities of carbon dioxide + four fatty acid ester systems, including oleic acid methyl ester, linoleic acid methyl ester, eicosapentaenoic acid ethyl ester, and docosahexaenoic acid ethyl ester were measured by using two circulating systems consisting of two vibrating tube densitometers. The vapor-phase densitywas observed to increase more significantly with pressure than the liquid-phase density at constant temperature. Experimental equilibrium constants of oleic acid methyl ester and linoleic acid methyl ester were found to be larger than those of eicosapentaenoic acid ethyl ester, docosahaxaenoic acid ethyl ester, linoleic acid, triolein, and tocopherol. This indicates that the two methylated fatty acidswould be extracted easier than the other compounds in a separation process using supercritical CO2 extraction. The equilibrium data were successfully correlated using the Peng Robinson and modified Soave Redlich Kwong equations of state with quadratic (two parameters), Panagiotopoulos Reid (three parameters), and Adachi Sugie (three parameters) mixing rules. In general, the Soave Redlich Kwong equation of state with the Panagiotopoulos Reid mixing rules and the quadratic mixing rules give the best correlation for methylated fatty acids and ethylated fatty acids, respectively.