Extraction Mechanism of Rare Earth Metals in the Presence of Diethylenetriaminepentaacetic Acid in Aqueous Phase

Abstract

The extraction rates of Er³⁺ and Y³⁺ from an aqueous phase containing diethylenetriaminepentaacetic acid (DTPA) to an organic phase containing di(2,4,4-trimethylpentyl) phosphinic acid in n-heptane were experimentally determined with both a transfer cell having a constant interface area and an agitated vessel in which organic phase was dispersed finely. The selectivity obtained was about 5.5, which was much larger than that by the usual solvent extraction: The selectivities for the various cases were studied in detail. The extraction rates and selectivity were quantitatively analyzed by taking account of the dissociation reactions of the rare earth metal DTPA complexes in the aqueous stagnant layer.