Competition between Redlich–Kister and adapted Herráez equations of correlation conductivities in isobutyric acid + water binary mixtures near and far away from the critical temperature

Abstract

Electrical conductivity deviation Δσ has been investigated by using electrical conductivity (σ) measurements for isobutyric acid + water (IBA + W) mixtures over the entire range of mole fractions at six different temperatures, both near and close to the critical temperature (0.055 < (T − T c)/K < 16.055). Knowledge of the conductivity of binary mixtures is of great importance in many industrial processes. Rarely can the conductivity of mixtures be obtained from the sum of the conductivities of the pure components. The theoretical study of the conductivity of mixtures is generally complicated. Numerous empirical correlation models have been proposed. The present study proposes a new empirical correlation equation, based on lineal behaviour. The results were also fitted with the Redlich–Kister polynomial equations and the recently proposed Herráez equation for viscosity correlation which is adapted for electrical conductivity in this work. The investigation of the Herráez equation shows that it exhibits a universal exponent as a physical magnitude feature. Competition between the two models at different temperatures and parameter numbers is discussed.