(217ak) Modeling of Dielectric Properties of Complex Fluids With the Electrolyte CPA Equation of State

Maribo-Mogensen, B., Technical University of Denmark
Kontogeorgis, G., Center for Energy Resources Engineering (CERE), Technical University of Denmark
Thomsen, K., Technical University of Denmark

The static permittivity is a key property for describing solutions containing polar and hydrogen-bonding compounds, and is the single most important physical property for describing the ion-ion interactions in mixtures containing electrolyte [1,2]. The static permittivity has commonly been described through empirical or semi-empirical correlations for the pure compounds [3] or mixtures [4]. In a recent publication we show that it is possible to simultaneously calculate thermodynamic and dielectric properties of complex mixtures [2], by combining the Onsager / Kirkwood / Fröhlich framework for dipolar fluctuations with a simple geometrical model for the dipolar correlations and an advanced equation of state (CPA - Cubic Plus Association) that takes into account molecular association through the Wertheim TPT1 perturbation theory. The model is extended to include the effect of ion-solvent association on dielectric properties in electrolyte mixtures from the ion coordination number fitted to volumetric data.

We show how the model is used to correlate the volumetric, dielectric, and thermodynamic properties over wide ranges of temperature and pressure for pure compounds and subsequently predict the properties for binary and ternary mixtures. 

[1] B. Maribo-Mogensen, G. M. Kontogeorgis, K. Thomsen, Comparison of the Debye–Hückel and the Mean Spherical Approximation Theories for Electrolyte Solutions, Ind. Eng. Chem. Res. (2012), 51, 5353–5363

[2] B. Maribo-Mogensen, G. M. Kontogeorgis, K. Thomsen, Modeling of Dielectric Properties of Complex Fluids with an Equation of State, J. Phys. Chem. B (2013), 117 (12), p. 3389-3397

[3] Fernández, D. P., Mulev, Y., Goodwin, A. R. H., & Sengers, J. L, A database for the static dielectric constant of water and steam, J. Phys. Chem. Ref. Data, (1995) 24, 33.

 [4] Harvey, A. H., & Prausnitz, J. M., Dielectric constants of fluid mixtures over a wide range of temperature and density, J. Sol. Chem. (1987),16(10), 857-869.