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Analysis of the UNIFAC-Type Group-Contribution Models at the Highly Dilute Region. 1. Limitations of the Combinatorial and Residual Expressions

1997; American Chemical Society; Volume: 36; Issue: 11 Linguagem: Inglês

10.1021/ie960770c

1520-5045

Epaminondas Voutsas, Dimitrios P. Tassios,

Advanced Chemical Physics Studies

An analysis of the behavior of UNIFAC-type group-contribution models at the infinite-dilution region is presented. It is shown that the modified UNIFAC and Entropic-FV combinatorial expressions account satisfactorily for the combinatorial effects, but not the Flory−Huggins and original UNIFAC ones. It is also shown that available residual terms fail to account sufficiently for the residual effects, performing actually better when combined with the aforementioned poorer Flory−Huggins and original UNIFAC combinatorial expressions. The ensuing implications of these limitations of the residual terms on the accuracy of infinite-dilution activity coefficient correlation are then demonstrated.