Selection of solvent extraction reagent for the separation of europium(III) and gadolinium(III)

This work has been aimed at identifying suitable conditions for the separation of europium/gadolinium mixture, with a high Gd content and without previous europium reduction, into a phase of high-purity Gd and a Eu-enriched mixture. Acid and basic extractants have been evaluated in a number of experimental conditions. Two acid extractants were investigated, DEHPA and (HEH(EHP)), the latter in its natural and saponified forms. Also, a series of basic extractants, Primene JM-T®, Primene 81R®, Alamine 336® and Aliquat 336® was evaluated. The Aliquat 336® was employed in chloride and nitrate forms. The experiments with acid extractants were carried out in hydrochloric medium, while the basic extractants were investigated in nitric and sulfuric medium. The selectivity achieved with Aliquat 336® (separation factor of 2.0) was superior to those obtained with the acid extractants (separation factors of 1.48 for DEHPA and 1.59 for HEH(EHP)).