AN NRTL MODEL FOR REPRESENTATION AND PREDICTION OF DEVIATION FROM IDEALITY IN ELECTROLYTE-SOLUTIONS COMPARED TO THE MODELS OF CHEN (1982) AND PITZER (1973)

A new method of representation of electrolyte solution nonideality is derived, on the basis of similar assumptions, from a model applied by J. L. Cruz and H. Renon to binary electrolyte solutions. In order to test the validity of the model for representation of strong electrolyte properties, parameters were fitted to osmotic coefficients data for single, completely dissociated salts in aqueous solutions and were used to calculate osmotic coefficients of mixed aqueous electrolytes. The average standard deviations for single electrolytes are within 1% in the case of 1-1 salts for the three models, and within 2% in the other cases, except for C. C. Chen's model (5%). As for predicted results, both local-composition models yield standard deviations of less than 2%, while the accuracy given by the K. S. Pitzer model is better than 1. 5%.