The Reliability of Published LLE Correlation Parameters in Phase Equilibria: A Continuing Challenge

Abstract

A few years ago, we conducted a study in which we detected a surprisingly high number of inconsistent liquid–liquid equilibrium (LLE) correlation results published in journals with high-quality reviewing processes. The main conclusion was the necessity of designing a strategy for validation of the parameters of the activity coefficient models prior to publication. In the present paper, a new survey of this problem has been carried out by means of the selection of 10 papers, which include experimental LLE data of a total of 26 ternary systems, some of them measured at different temperatures (52 LLE data sets), and all of them correlated using both NRTL and UNIQUAC models, resulting in 104 correlation results checked. The fulfillment of phase equilibrium criteria and the consistency of the parameters in all of the composition diagrams, including the totally miscible binary subsystems, have been the aspects inspected. A very worrying number of published correlation results have proven to be incorrect. Only in one of the selected papers were all of the correlations consistent. Regarding the number of correlations, 78 of a total of 104 correlations (75%) were inconsistent. New validated correlation results are presented for those systems inconsistently correlated in the literature.