NEW SCREENING TECHNIQUE AND CLASSIFICATION OF SALTS FOR THE SALT DISTILLATION OF CLOSE-BOILING AND AZEOTROPIC SOLVENT MIXTURES.

Abstract

A basis for classifying dissolved salts in solvent mixture according to their vapour pressure-temperature relationships and the ratio of their salt-solvent interaction parameters has been proposed. The system of classification provides a simple and rapid screening method for a suitable salt for the separation of close-boiling and azeotropic solvent mixtures by salt distillation. Altogether six classes of salts can be identified and their characteristics are described and discussed with respect to the salting-in or salting-out of the solvent component by the salt in a given solvent mixture. The basis and procedure for the classification are applied to 39 alcohol-water-salt systems. The results confirm the validity of such a system of classification. This study therefore provides a unique and rapid screening method for selection of a salt for a salt distillation process.