(12a) Consistent Modeling of Phase Behavior and Liquid Viscosity of Non-Ideal Solutions

A previously developed Eyring's theory model [1] proved to give an accurate description of viscosity behavior of highly non-ideal liquid solutions within wide ranges of temperature and pressure. In doing so, the model uses a cubic equation of state (CEoS) along with modern mixing rules of the Wong-Sandler type to reasonably compute volumetric properties and the excess activation energy of flow for the liquid mixture of interest. However, the excellent performance of the viscosity model was achieved at the expense of adversely affecting phase behavior calculations since the excess Gibbs energy of the mixture obtained from the CEoS was manipulated to match the experimental excess activation energy of flow. To remedy this inconsistency, in this work we propose a new modeling approach by introducing a residual term of the excess activation energy in such a way to keep the same accuracy in viscosity calculations without altering the phase behavior computed from the CEoS. Various binary mixtures including non-aqueous and aqueous solutions were considered to confirm the goodness of the present modeling approach.

[1] Macías-Salinas et al., Fluid Phase Equilibria, 210, 319 (2003).