Application of the GCA-EOS model to the supercritical processing of associating oil derivatives: fatty acids, alcohols and triglycerides

O. FERREIRA; S. PEREDA; S.B. BOTTINI

Versailles, France

Simposio; 6th International Symposium on Supercritical Fluids; 2003

International Society for Advancement of Supercritical Fluids (ISASF)

Supercritical processes are of interest in the fatty oil industry for a variety of applications: extraction and refining, removal of pollutants, recovery of specialties, hydrogenation of oils and derivatives, etc. Typical process mixtures include heavy compounds and gases at near-critical conditions. At high pressures these asymmetric systems present a complex multi-phase behavior, difficult to model. This complexity increases if some of the mixture components are able to self- and/or cross associate. Recently (Espinosa et al., J. of Supercritical Fluids, 23, 91, 2002) the group contribution equation of state GC-EOS (Skjold-Jorgensen, Fluid Phase Equilibria, 16, 317, 1984) has been successfully applied to model the phase behavior of mixtures of supercritical fluids with fatty oils and derivatives. In the present work an extended version of this model, the group contribution with association equation of state GCA-EOS (Gros et al., Fluid Phase Equilibria, 116, 535, 1996) is used to represent high pressure phase equilibria in mixtures of supercritical gases (carbon dioxide, propane, ethane, dimethyl ether) with fatty oil derivatives, such as mono- and di-glycerides, fatty acids, alcohols, water and esters. Self- and cross-association between the associating groups present in these mixtures are considered. Satisfactory correlation and prediction of equilibrium data are obtained. The capacity of the model to follow the behavior of the solutions towards the limit at infinite dilution of the associating components is of particular importance.