Further studies of the rate affected synergic solvent extraction of Fe(III)-TTA—II: The effect of tributyl phosphate on the solvent extraction of iron(II) with 2-thenoyltrifluoroacetone

Abstract

The extraction of iron(III) from aqueous perchloroc acid into a solution of 2-thenoyltrifluoroacetone (TTA) in benzene is known to be very slow. The system does not reach equilibrium within a practical contact time of the two phases. The rate and percent of iron(III) extraction was found to increase considerably upon the addition of tributyl phosphate (TBP). An increase in temperature of 10°C results in further increase in the rate and percent of iron(III) extraction by a factor of 1·5. From the results of detailed investigation, the reason for this effect is considered to be the replacement of a slow step (the direct formation of the iron(III)-TTA complex in the aqueous phase) by a series of fast reactions (the formation of an iron(III) TBP complex in the aqueous phase, the extraction of the iron-(III)-TBP complex to the organic phase, and the replacement of TBP by TTA in the organic phase). All the observations in this system are readily explained by the previously demonstrated kinetic effect.