Modeling Viscosity of Multicomponent Electrolyte Solutions

A comprehensive model for calculating the viscosity of aqueous electrolyte solutions has been developed. The model includes a long-range electrostatic interaction term, contributions of individual ions, and a contribution of specific interactions between ions or neutral species. The long-range electrostatic term is obtained from the Onsager-Fuoss theory, whereas the individual ionic contributions are calculated using the Jones-Dole B coefficients. A technique for predicting the temperature dependence of the B coefficients has been developed on the basis of the concept of structure-breaking and structure-making ions. The contribution of specific interactions between species, which is dominant for concentrated solutions, has been found to be a function of the ionic strength. The model reproduces the viscosity of aqueous systems ranging from dilute to concentrated solutions (up to ca. 30m) at temperatures up to 573 K with an accuracy that is appropriate for modeling industrially important systems. In particular, the viscosity of multicomponent systems can be accurately predicted using parameters obtained from single-solute systems.