Kinetic studies of the solvent extraction of metal complexes—III: The rate of extraction and back-extraction of gallium(III) thenoyltrifluoroacetonate chelate in aqueous perchlorate solution-chloroform systems

Abstract

The rate of forward extraction of Ga 3+ from 0·1 M aqueous perchlorate solutions into chloroform with TTA (thenoyltrifluoroacetone, denoted by HA) and of backward extraction of the tris-TTA chelate, GaA 3, have been determined under various conditions. The distribution equilibria in the same systems have also been measured. The rate of forward extraction is proportional to [Ga 3+], [HA] org, and [H +] −2, whereas that of backward extraction is proportional to [GaA 3] org, [HA] org −2, and [H +]. On the basis of these results, the rate determining step in the forward extraction is believed to involve an association of the GaOH 2+ species with A − in the aqueous phase and that in the backward extraction to be the reverse reaction of this. The constants for both the rate controlling steps have been determined and the extraction constant computed from these values is found to agree with that computed from the equilibrium data.