An Evaluation of Four Electrolyte Models for the Prediction of Thermodynamic Properties of Aqueous Electrolyte Solutions

In this work, the performance of four electrolyte models for the prediction of the osmotic and activity coefficients of different aqueous salt solutions at a temperature of 298 K, at atmospheric pressure, and in a wide range of concentrations is evaluated. In two of these models, namely electrolyte non-random two-liquid (e-NRTL) and mean spherical approximation non-random two-liquid (MSA-NRTL), the association between ions of the opposite charges for simplification purposes is ignored, but in the other two ones, namely associative mean spherical approximation non-random two-liquid (AMSA-NRTL) and binding mean spherical approximation (BiMSA), association and solvation effects are considered. The predictions of these four models for the osmotic and activity coefficients of electrolyte solutions at a temperature of 298 K and at atmospheric pressure are compared with the experimental data reported in the literature. This comparison is performed for 28 different aqueous salt solutions, including thio-cyanates, perchlorates, nitrates, hydroxides, quaternary ammonium salts, and others. The results show that the performance of the models which consider association effects is better than the others, especially for higher salt concentrations. However, the best performance belongs to the BiMSA model, which has some parameters with physical meaning.

Keywords:

Electrolyte Models , Osmotic Coefficient , Activity Coefficient , Thermodynamic Properties