The Kinetics of Metal Solvent Extraction

I. EXTRACTING REAGENTS

In the present review, dealing with the kinetics of solvent extraction of metal species, we will consider biphasic systems consisting of:

1. An aqueous electrolyte solution containing a metal cation which, according to the nature and composition of the electrolyte, can exist either as a free (hydrated) ion or as neutral, positively or negatively charged complex species

2. An organic phase which is a solution, in a water-immiscible organic diluent, of an organic molecule called extractant; only organic diluent not exhibiting appreciable extraction properties by themselves will be considered; the extractant will instead be a molecule capable of reacting with the aqueous metal species, transferring them into the organic phase; this reactivity is conferred to the extractant by the presence of a functional group which has binding properties with respect to the metal species; the only purpose of the diluent will then be that of dissolving the extractant and possibly to improve its physical properties