A new local composition model for predicting of activity coefficient and solubility of amino acids and peptides in water

The local composition models, such as M-Wilson, NRTL and M-NRTL models have been used to predict the activity coefficients of amino acids and simple peptides in water. In this study, the binary interaction parameters of the local composition models for water–amino acid and amino acid–water molecules have been calculated. The results obtained from the models have been compared with the experimental data of activity coefficients and the deviations of all those models have been reported, too. It is shown that M-NRTL model can more accurately predict the activity coefficients. The models have been also used to predict the solubility of amino acids in water. The results show that the M-Wilson model can accurately predict the solubility of amino acid at a wide range of temperatures. Finally, the values of Δh, Δs and Δg of the solutions have been calculated.