Competition between Redlich-Kister and improved Herraez equations of correlation viscosities in 1,4-dioxane +water binary mixtures at different temperatures

Viscosity deviation has been investigated by using density and kinematic viscosity measurements for dioxane + water mixtures over the entire range of mole fractions at atmospheric pressure and in five temperatures (293.15, 298.15, 302.15, 306.15 and 309.15 K). This system exhibited very large positive values of [image omitted] due to increased hydrogen bounding interactions between unlike molecules in the cluster formation region and to very large differences between the molar volumes of the pure components. The results were fitted with the Redlich-Kister equations and the recently proposed Herraez equation. This last model was improved by fixing the first constant of the corresponding exponential function. Competition between the two models at different parameter numbers is discussed. We note that, in this system, where the viscosity versus molar fraction of dioxane presents a maximum, experimental data are in agreement with the two models when more than three parameters are employed.