MODELING BINARY PHASE-BEHAVIOR OF SUPERCRITICAL CARBON-DIOXIDE AND FATTY-ACID ESTERS

Regular solution theory was applied for the modeling of binary vapor-l iquid equilibria of SC CO2 and eicosapentaenoic acid (EPA) and docosah exaenoic acid (DHA) ethyl esters. The mathematical relationship betwee n the critical phase solubility of both esters and solubility paramete r for SC CO2 was determined to be logarithmic. Correlations were prese nted to describe solubility isotherms at 40, 50, and 60-degrees-C. In order to make the model rigorous, equilibrium distribution coefficient s (K) of EPA and DHA ethyl esters in critical and liquid phases were e stimated using the theory and compared with literature data. The model predicted the increasing trend in K values as a function of pressure for all investigated isotherms. Estimations of the model were in agree ment with the experimental K values at conditions away from the critic al point.