A decorated lattice model, ensemble-averaging the decorated lattice, was applied to predict the liquid-liquid equilibria of water-pyridine derivative systems exhibiting an asymmetric closed loop type of T-x diagrams.
The model consists of primary and decorated cells, constituting the partition function of the decorated bond in terms of intermolecular interactions between sites, and of configurations. In the comparative study with a solution model, i.e., UNIQUAC, this model was examined in the agreement of experimental data, the shape of closed loop, and the phase behavior in the vicinity of critical points including the loci of upper critical solution temperature(UCST) and lower critical solution temperature(LCST). Further some examples of water-pyridine derivative systems exhibiting closed loop type of T-x diagrams were demonstrated successfully with physicochemically sound directional interaction energies.
The model also provided a possibility in predicting the abnormal phase envelope, but still in progress for computational techniques.