Yt. Wu et al., PREDICTION OF LIQUID-LIQUID EQUILIBRIA OF POLYMER-SALT AQUEOUS 2-PHASE SYSTEMS BY A MODIFIED PITZERS VIRIAL EQUATION, Fluid phase equilibria, 124(1-2), 1996, pp. 67-79
A modified Fitter's virial equation, which combines the long-range ele
ctrostatic contribution from Fowler and Guggenheim with the short-rang
e virial equation, is presented for the excess Gibbs free energy of so
me special kinds of systems. The model is used to predict the liquid-l
iquid equilibrium (LLE) at 298.15 K of three polymer-uni-bivalent salt
-aqueous two-phase systems: polyethylene glycol(PEG)-(NH4)(2)SO4, PEG-
Na2SO4, PEG-Na2CO3 by correlating the parameters from the correspondin
g vapor-liquid equilibrium (VLE) data. The results show that the model
can give excellent representation of the VLE data of PEG solutions, e
ither binary or ternary, the model parameters being independent of the
chain lengths of the polymers. The comparison between the predicted a
nd experimental phase diagrams shows that the suggested model has good
prediction ability for PEG-uni-bivalent salt systems.