MODEL PREDICTION OF SUPERCRITICAL FLUID-LIQUID EQUILIBRIA FOR CARBON-DIOXIDE AND FISH-OIL RELATED-COMPOUNDS

The goal of this work is to provide a purely predictive method for the computation of phase equilibria of mixtures involving fish oil and su percritical carbon dioxide. For this purpose, the Huron-Vidal first-or der (MHV1) and second-order (MHV2) mixing rules have been investigated in order to combine the Soave-Redlich-Kwong equation of state with di fferent excess Gibbs energy based models, such as the linear UNIFAC/UN IQUAC, the modified UNIFAC/UNIQUAC, and the Van Laar models. For the m ixture b parameter of the equation of state, a linear and a van der Wa als like quadratic expression have been considered. The approach that has yielded the most satisfactory results over a wide temperature and pressure range is the MHV1 mixing rule used together with the modified UNIFAC model and a quadratic expression for the mixture b parameter w ith a universal constant for all investigated systems (saturated and p olyunsaturated free fatty acids/fatty acid methyl or ethyl esters in s upercritical carbon dioxide). The UNIFAC group interaction parameters involving carbon dioxide and fish oil related compound groups have bee n estimated using binary vapor-liquid equilibrium data. For the invest igated systems, the MHV1 and MHV2 mixing rules were found to give sati sfactory predictions considering the quality of the experimental data.