EXTRACTION OF CARBOXYLIC-ACIDS WITH AMINE EXTRACTANTS .1. EQUILIBRIA AND LAW OF MASS-ACTION MODELING

Studies have been made of the extraction of acetic, lactic, succinic, malonic, fumaric, and maleic acids by Alamine 336, an aliphatic, tertiary amine extractant, dissolved in various diluents. The results were interpreted by a “chemical modeling” approach, in which the stoichiometries of acid-amine complexes and corresponding equilibrium constants which best represent the experimental results were determined. The acids studied differed in pKaand in the presence or absence of functional groups other than the primary carboxyl group. Diluents were chosen from different chemical classes—electron donating, electron accepting, polar, and nonpolar—so as to examine the effects of diluent-complex interactions. These interactions were found to affect both the stoichiometry of reaction and the magnitudes of the corresponding equilibrium constants. The conclusions reached from these data are compared with those from previous studies. © 1990, American Chemical Society. All rights reserved.