Modeling the phase equilibrium of soybean oil deodorizer distillates plus supercritical carbon dioxide using the Peng-Robinson EOS

The Peng-Robinson EOS was used to predict vapor-liquid equilibrium (VLE) of the multicomponent mixture soybean oil deodorizer distillates (SODD)/CO2. The composition of SODD from the Cia. Riograndense (RS, Brazil) was used. SODD was treated as a mixture containing fatty acids (palmitic, oleic, and linoleic), sterols (stigmasterol), tocopherols (alpha -tocopherol), and squalene. The interaction parameters were obtained from solubility and/or VLE data available in the literature for the binary pairs of SODD compounds/carbon dioxide. For the binary systems SODD compound i/SODD compound j, the interaction parameters were set equal to zero. The results were compared with literature data using distribution coefficients and selectivities. The selectivity was calculated by reducing the mixture to a pseudo-binary system containing a light and a heavy compound. The modeling of the system SODD/CO2 using the Peng-Robinson EOS has proven to be a powerful tool for obtaining preliminary information of VLE of complex systems and for guiding experimental vapor-liquid equilibrium measurements.