Acid-base-coupled extractants

Eyal, A. M. Kogan, L. Bressler, E. Extraction of metal salts by mixtures of water-immiscible amines and organic acids (acid-base couple extractants). 2. Theoretical treatment and analysis. Ind. Eng. Chem. Res. 1994, 33, 1076-1085. 

ACID EXTRACTION BY ACID-BASE-COUPLED EXTRACTANTS... 

Acid-base-coupled extractants seem to be very attractive for many industrial applications. They allow recovery of acids from waste streams instead of neutralization. Acid and base consumption is thereby reduced, as is the amount of waste to be disposed of. Being also excellent extractants for metal salts, ABC extractants provide for sequential recovery of acids and their salts from waste streams. The extractant composition can be adjusted so that a single extractant can extract first the acid and then the salt at high efficiency, selectivity, and reversibility. Because of this high reversibility, these components are recovered by back-extraction with water, at concentrations approaching those in the feed stream and in some cases even higher. 

E. Bressler and A. M. Eyal, Extraction of ZnSO by acid base couple extractants, Proceedings of Int. Solv. Extr. Conf, 1993, Vol. 1, pp. 549—556. 

Acid-base-coupled extractants (i.e., mixed liquid cation and anion exchangers) promise to be very versatile reagents for the extraction of metal salts, mineral and organic acids, and even amino acids. The extractants are based on ideas presented by Grinstead and coworkers some 30 years ago,... 

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