Revising concepts on liquid–liquid extraction: data treatment and data reliability

The intention of this article is to clarify some concepts and relevant aspects of the experimental determination and treatment of liquid–liquid equilibrium data for ternary systems. Distinction is made between solubility curve and binodal curve, setting the stability limit which is defined by the spinodal curve. In addition, it is recommended to carry out the equilibrium data correlation using semiempirical models with a thermodynamic base, over the use of empirical equations. Moreover, the misuse of these empirical equations (Hand, Bachman, Othmer-Tobias, etc.) as proof of data quality or consistency is clarifiedA.A. and O.R. acknowledge financial support from Xunta de Galicia, project Consolidación e estruturación 2020 ED431B 2020/21S