A modified mean spherical approximation model for prediction of mean ionic activity coefficient in mixed electrolyte solution at different temperatures

In this work, the Dehghani–Modarress mean spherical approximation model has been modified and extended for prediction of the mean ionic activity coefficient in mixed aqueous electrolyte solutions at different temperatures. In the DM-MSA model the cationic diameter as well as the dielectric constant of water are considered to be concentration dependent. In order to make the DM-MSA model applicable in engineering applications, a binary interaction parameter has been introduced. Using these parameters, the mean ionic activity coefficient of electrolytes can be predicted applying a linear mixing rule. To calculate the activity coefficient of single electrolytes at different temperatures, a temperature dependency has been considered for cationic size as well as dielectric constant. Utilizing the obtained parameters for single electrolytes at different temperatures, the mean ionic activity coefficients of mixed electrolytes have been predicted. The accuracy of the model is also compared with those results produced by extended UNIQUAC model. In order to have a fair judgment, the same experimental data and minimization algorithm have been used for comparison.

► Modification on MSA model for application in mixed electrolyte solutions.
► Prediction of activity coefficients in mixed electrolyte solutions using single electrolyte activity coefficients.
► Prediction of activity coefficients in mixed electrolyte solutions at different temperatures.