Viscosity Modeling and Prediction of Aqueous Mixed Electrolyte Solutions

Viscosity values of the ternary aqueous mixed electrolyte solutions have been correlated with models based on the Eyring's absolute rate theory and the electrolyte NRTL, modified NRTL, and Wilson theories for calculating the excess Gibbs energy of activation of the viscous flow. Utilization of the mixing rule assumption in the viscosity parameter of Einstein's relation has made it possible to use the binary parameters of the local composition models in extending of these equations to the ternary electrolyte systems. Performance of the investigated models in the con-elation of the viscosity data of the ternary mixed electrolytes + H2O systems is good. A new semiempirical equation has also satisfactorily been used to correlate the viscosity of the ternary aqueous multielectrolyte solutions. The quality fitting of this semiempirical equation is much better than the aforementioned local composition models. A simple exponential equation with consideration of the temperature dependency has also been used to correlate the viscosity values of solute. Usage of calculated solute viscosity in the suitable mixing rule made it possible to predict the viscosity of aqueous mixed electrolyte solutions. The agreement between the predicted and experimental viscosity values of aqueous multielectrolyte solutions is excellent over the entire composition and temperature range.