Liquid-Liquid Equilibrium of Associating Fluid Mixtures Using Perturbed-Hard-Sphere-Chain Equation of State Combined with the Association Model

Perturbed-hard-sphere-chain-association (PHSC-AS) equation of state, which is defined by incorporating the association term of the statistical associating fluid theory (SAFT) model into the PHSC equation of state with van der Waals-type dispersion term, is used to calculate the liquidliquid equilibrium (LLE) for complex associating mixtures such as alcohol/alkane, water/alkane, acetic acid/alkane, alcohol/water, and carboxylic acid/water systems. In this work, the PHSC-AS models with two different chain terms have been investigated. One is the original model proposed by Song et al. [ Macromolecules 1994, 27 (2), 441-448], and the other is the modified model whose chain term was replaced with that of the SAFT model. The calculated results of LLE for associating mixtures are compared with those by the purturbed-chain-SAFT (PC-SAFT) model as well. The results with PHSC-AS and PC-SAFT equation of state are in acceptable agreement with the experimental data. Despite the simple dispersion equation with van der Waals-type, PHSC-AS models show a reasonable calculation performance for LLE of associating fluid mixture.