CORRELATION OF LIQUID-LIQUID PHASE-EQUILIBRIA USING THE SAFT EQUATION OF STATE

An equation of state (EOS) derived from the statistical associating fluid theory (the SAFT equation of state (EOS), Chapman et al., 1990) is applied to liquid-liquid equilibrium (LLE) calculations of mixtures including self-associating components. The SAFT EOS is employed in this study on 41 binary and eight ternary mixtures which include alkanol, water, carboxylic acid, amine and n-alkane compounds. The temperature dependence of the SAFT EOS behaves satisfactorily in predicting the binodal curves. The binary interaction parameters of the SAFT EOS are found to be a function of molecular weight for families of binary systems. The accuracy of LLE calculations using the SAFT EOS is reported and is compared with that of the UNIFAC model or the Peng-Robinson EOS with van der Waals mixing rules. The SAFT EOS with generalized binary parameters yields superior results to those from other methods.