Convergence of Tie Lines in Ternary Liquid Systems and its Application to Liquid Extraction

Abstract

Most ternary systems of interest for liquid-liquid extraction work contain one pair of immiscible liquids and are such that the two liquid phases are formed over a wide range of concentrations. Usually the literature gives only limited information on the tie lines of these systems. Therefore, interpolation is necessary to obtain further data. One of the methods used for interpolation is based on the observation that tie lines appear to converge to a point on the extension of the base of the representative triangle. This convergence of tie lines, first reported by Tarasenkov and Pologentzeva (1) in 1932, has since been a source of discussion among phase diagram investigators (2,3). For most systems insufficient accuracy of the present tie-line data makes it impossible to determine whether tie lines intercept the extension of the base of the triangle at one focus point; however, in many cases the intercepts are spread over a very narrow distance, and the assumption that there is a common point is at least a useful approximation for interpolation of the data.