APPLICATION OF PREFERENTIAL SOLVATION CONCEPT FOR INTERPRETATION OF THE MECHANISMS OF SOLVENT EXTRACTION. I. ACID SOLVENT EXTRACTION BY AMINES. II. METAL SOLVENT EXTRACTION BY ACIDIC EXTRACTANTS

摘要

A novel competitive complexation/solvation modeling approach is introduced to explain the mechanisms of solvent extraction. The theory is based on the modified competitive preferential solvation theory, the concept of amphoteric properties of extractants and the concept of different aggregation structures' formation at increasing extractant loading. Four possible stages of extraction behavior, interacting mechanisms and aggregate structures formation, depending on solute-solvent affinity constant ratios and solvent concentrations, are discussed. Extractants are considered amphoteric and may perform as acids (electron acceptors) or bases (electron donors). A mathematical description for quantification of the results is also introduced. Based on the presented theory, analysis of different acid-amine and metal ion-organic acid extraction systems are presented. It gives a key for preliminary quantitative prediction of suitable extraction systems.