Prediction and experimental verification of the salt effect on the vapour-liquid equilibrium of water-ethanol-2-propanol mixture

Abstract

Experimental vapour-liquid equilibria of water-ethanol-2-propanol saturated with NaNO3, NaCl, KCl and containing 0.05mol CH 3COOK/mol total solvent compared well with those predicted by Tan-Wilson and Tan-non-random two liquid (NRTL) models for multicomponent solvent-solute mixture using a set of solvent-solvent interaction parameters obtained from the regression of the vapour-liquid equilibrium of the solvent mixture without the dissolved solute and a set of solute-solvent interaction parameters calculated from the bubble points of the individual solvent components saturated or containing the same molar ratio of solute/total solvents as the mixture. The results also showed that a solvent component i is salted-in or out of the liquid phase relatively more than solvent component j would depend on whether Asj/Asi (Tan-Wilson model) or exp(τis-τjs) (Tan-NRTL model) is less or greater than 1. This is consistent with earlier publications on the effect of dissolved solutes (electrolytes and non-electrolytes) on the binary solvents mixtures. These findings confirmed that Tan-Wilson and Tan-NRTL models for multicomponent solvent-solute system can provide an accurate and rapid screening of electrolytes and non-electrolytes for their suitability in facilitating solvent separation by salt distillation of ternary solvent mixtures simply by determining the relative ratios of the solute-solvent interaction parameters from the respective bubble points of the solvent components containing the dissolved solute. The results also suggest that this may also be extended to other multicomponent solvent mixtures. © 2003 Elsevier B.V. All rights reserved.