Approximate design method for reactive liquid extractors based on thermodynamic equilibrium correlations

Abstract

Approximate methods are suitable for rapid analysis of alternatives during the conceptual phase of a process design. Few approximate methods for liquid–liquid extraction have been published and few theoretical studies have been carried out in this field on reactive liquid extractors. The purpose of this study was to provide a simple, reliable and rapid approximate method for the design of separation columns for liquid mixtures that have reacted and are in a simultaneous equilibrium of reaction and phases. The developed design method involves two stages: (a) analysis of the liquid–liquid equilibrium correlations with no reaction and their extension to reactive systems and (b) coupling of the correlations with the stage by stage design method. Hand, Othmer–Tobias and Bachman–Brown correlations were used for the tie lines fit; whereas Hlavatý, log γ and β function were used for the solubility curves.The correlations, in terms of transformed variables, were applied to six reactive systems that presented adequate fits for the design of the reactive liquid extractors. The following cases were used to compare the results obtained with the approximate design method with those reported in the literature: (i) The hydrolysis of methyl octanoate, (ii) A theoretical system with five components and parallel reactions, and (iii) The esterification of acetic acid with n-propanol; a very good agreement was found.