For the thermodynamic approach, it's noticeable that the models using NRTL and UNIQUAC had a better performance, with RMSEs mostly below 1K (Table ). This was expected because the binary interaction parameters of these two models were fitted to the experimental data, so the deviation tends to be minimized. Moreover, Tables and show that the models using UNIFAC resulted in reasonable prediction. The accuracy was not as good as the UNIQUAC or NRTL, but the results were also satisfactory for a predictive activity coefficient model. Finally, the model considering the mixtures as ideal was the worst of the thermodynamic approaches; the only situation in which the deviation was not significant was when the butanol molar fraction was close to 0 or 1, where the mixture behaved like a pure component.