This study proposed a new model based on the solvation phenomena. The ionic activity coefficients of individual ions of some 1:1 and 1:2 salts were correlated successfully. Comparison was made between the results of the present model and those of Khoshkbarchi–Vera (KV), Pitzer, and Lin–Lee models. The average relative errors for cation and anion were 3.03, 3.53, 3.45 and 1.24, 1.14, 1.38, respectively, in Lin–Lee, KV, Pitzer models, whereas they are 1.81 and 0.66 in the proposed model. These results show that the proposed model improved the correlation of the individual ionic activity coefficients. Contrary to arguments found in the literature, it is also demonstrated that the short-range solvation contribution is a linear function of ionic strength.
