Should we trust all the published LLE correlation parameters in phase equilibria? Necessity of their assessment prior to publication

Abstract

The review of a representative number of papers published in recent years that include the correlation of experimental liquid-liquid equilibrium (LLE) data has been carried out, after detecting serious inconsistencies in some of the parameters recently published. The result of this analysis shows that surprisingly many published parameters and calculated LLE data are inconsistent for different reasons, for instance: a) some parameters predict a type of system different from the experimental one, b) calculated tie-lines with the published parameters do not satisfy the Gibbs stability criteria, and c) in other cases do not even satisfy the isoactivity LLE condition. In most of these papers, the erroneous common final conclusion was a good agreement between the experimental and calculated tie-lines using these inconsistent parameters. Because these problems were not detected by the authors (when preparing the manuscript) nor by reviewers (during the review process), the necessity of a strategy for the validation of parameters (and compositions) calculated in LLE data fitting became evident. Such procedure should be applied to all LLE data correlation papers, prior to their publication in order to ascertain their consistency and quality. In this paper we suggest some possible tools that could be useful for this assessment.