From the correlation of binary systems involving supercritical CO2 and fatty acid esters to the prediction of (CO2-fish oils) phase behavior

In this paper, a purely predictive model for the phase equilibria computation of mixtures involving fatty acid esters (FAE) and supercritical carbon dioxide is proposed. In a first step, the phase equilibria modeling of FAE/CO2 binary systems were performed using the Peng-Robinson equation of state. To obtain a purely predictive model, the critical properties (T-c, P-c,) and the acentric factor (omega) of the FAE were estimated with specific correlations. Moreover, the group contribution method developed by Abdoul et al., which allows the prediction of binary interaction parameters (k(ij)), was extended to ester compounds and an additional group (the ester function) was defined. Such an approach allowed us to correlate with quite good accuracy all the binary FAE/CO2 systems. In a second step, dew points of (CO2/fish oil) systems were measured and the previous model was used to check its capability in predicting these data. The fish oil under study contained 30 different fatty acid ethyl eaters, and the model was able to predict with very good accuracy the measured saturation pressures.