Extraction by solvation:

How the extraction of a metal ion in the organic phase is possible. In this context, the extraction equilibria of some typical extraction systems are discussed. These systems include extraction of metal complexes, extraction by solvation, extraction by ion pair formation and extraction by synergism. The role of different aqueous and organic phase parameters has been explained. Taking a clue from the discussion, one gets into a position as to be able to identify the factors influencing extraction. The role of the different parameters has been elaborated by taking some appropriate examples. Once these factors are identified, it becomes possible to usefully employ them for separations. A section is devoted to illustrate some of the approaches which are generally adopted to achieve separations of metal ions. The discussion is supported by citing examples from extraction systems which have been exemplified earlier in this unit. It has been pointed out that solvent extraction has a wide variety of utility for industrial applications. Particularly, in this context, the choice of organic phase becomes very critical. The unit concludes with general criteria for the choice of the organic phase.