In this article we present a model for correlating dynamic and kinematic viscosities of liquid
mixtures, which is based on Eyring's absolute rate theory for liquid viscosity and the UNIQUAC
equation. The proposed model involves the concept of ideal viscosity and uses the UNIQUAC
equation to represent the deviation from ideal behavior. The expression adopted to describe the
ideal term viscosity has been chosen after a thorough investigation of the performance of different
equations previously proposed in the literature. The correlation results have shown a strong
dependence on the expression used to account for the ideal viscosity contribution. Besides size
and shape parameters, for each pure component, the model requires only two adjustable
parameters per binary system. The binary interaction parameters have been determined by
fitting literature viscosity data. More than 350 binary systems, 4619 viscosity data points at
0.1 MPa, have been correlated using this model. The binary systems investigated are
representative of different types of intermolecular interactions (e.g., nonpolar/nonpolar, nonpolar/polar, and polar/polar). The calculated values are in good agreement with the experimental ones.
The overall average mean relative standard deviation of the correlations is 1.20%, which is
comparable with those of other correlation models available in the literature.
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%.
The calculation of the viscosity of 51 multicomponent (48 ternary and 3 quaternary) nonelectrolyte liquid systems has been performed by means of a model based on Eyring's theory of viscous flow and the UNIQUAC equation. More than 1000 viscosity data points, under 0.1 MPa and in the temperature range of 283.15-323.15 K, have been calculated. The model is based on purecomponent viscosities, pure-component molar volumes, and pure-component size and shape parameters, as well as two interaction parameters per binary system. The model binary interaction parameters were determined previously by correlation of experimental literature data on the viscosity of binary systems. A rather good agreement between experimental and calculated viscosities of ternary and quaternary liquid mixtures has been achieved. The overall mean relative standard deviation of the calculation is 2.95%. The results show that the model is adequate for estimating liquid mixture viscosities for different types of mixtures containing polar and nonpolar components.
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