In this article we present a new model for correlating dynamic viscosity of binary strong electrolyte solutions. The proposed model is based on Eyring's absolute rate theory and the Debye−Hückel model for calculating the excess (electrostatic) free energy of activation of the viscous flow. In the present model we consider that the free energy of activation of the viscous flow as being the same as the appropriate thermodynamic free energy used for calculating equilibrium properties of the electrolyte solution. Modifications of Eyring's absolute rate theory must be performed to take into account the solvent as a continuous medium, as considered in the Debye−Hückel theory. This is accomplished by means of the osmotic-pressure framework for solutions. In this framework one adopts a thermodynamic free energy, which is considered as a function of the absolute temperature, pressure, number of moles of the solute species, and chemical potential of the solvent. The proposed model contains two adjustable parameters that have been fitted by means of experimental viscosity data of the literature. The total number of 21 binary electrolyte systems (at 0.1 MPa and 25 °C) with different solvents (water, methanol, ethanol, and 1-butanol) have been studied. The calculated viscosity values are in good agreement with the experimental ones. The overall average mean relative standard deviation is 0.52%.

In the present article, a recently published model (Esteves, M. J. C.; Cardoso, M. J. E. de M.; Barcia, O. E. Ind. Eng. Chem. Res. 2001, 40, 5021) for calculating the viscosity of binary strong electrolyte solutions, at 25 °C and 0.1 MPa, has been extended for calculating the viscosity of binary strong electrolyte solutions at different temperatures. A temperature dependence has been introduced into the two adjustable parameters of the original model. The empirical expression originally proposed by Silvester and Pitzer (J. Phys. Chem. 1977, 81, 1822) to take into account the temperature dependence of thermodynamic properties of aqueous electrolyte solutions has been adopted. The proposed model contains a total of five adjustable parameters that have been fitted by means of experimental viscosity data in the literature. The total number of 20 binary electrolyte systems (at 0.1 MPa and in the temperature range of −35 to 55 °C) with two different solvents (water and methanol) have been studied. The overall average mean relative standard deviation is 0.98%

Viscosities and densities have been determined for some binary strong electrolyte solutionsKI + methanol, NH4I + methanol and NH4I + ethanolat (298.15, 303.15, 308.15, and 313.15) K and 0.1 MPa. The viscosity data have been analyzed using the three-parameter Jones−Dole equation (Kaminsky, M. Ion−solvent interaction and the viscosity of strong electrolyte solutions. Discuss. Faraday Soc. 1957, 24, 171−179), and the A, B, and D parameters have been calculated. A Debye−Hückel model for calculating the viscosity proposed by Esteves et al. (Esteves, M.; Cardoso, M.; Barcia, O. A Debye−Hückel model for calculating the viscosity of binary strong electrolyte solutions. Ind. Eng. Chem. Res. 2001, 40, 5021−5028. Esteves, M.; Cardoso, M.; Barcia, O. A Debye−Hückel Model for Calculating the Viscosity of Binary Strong Electrolyte Solutions at Different Temperatures. Ind. Eng. Chem. Res. 2002, 41, 5109−5113) has been used to correlate the experimental data.

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