UNIQUAC model extended to ionic solutions

The extension of the UNIQUAC model to ionic solutions was first envisaged by Sander et al. in 1986. The basic idea is to think of the excess Gibbs energy of an ionic solution as being the siun of two contributions  

from the excess Gibbs energy of die solution, we write  

For a given species /, this relation results in a relation between the activity coefficients, given by  

Normally, the UNIQUAC model leads to the activity coefficients with the pure-substance reference In Jq switch to the activity coefficient for 

The munber of parameters needed for this model, therefore, is less than that needed for Pitzer s model. 

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