Mutual Separation of Ln and an Using TODGA and DTBA with High Organic Acid Concentrations

ABSTRACT Developing the conventional separation method by which minor actinides (MA) such as Am and Cm are separated from lanthanides is important with respect to their recovery and isolation from high-level radioactive waste (HLW). Owing to the chemical behavior of trivalent lanthanide and actinide ions with similar ionic radii, realizing this separation is still challenging. All lanthanides, Am, and Cm can be extracted using diglycolamide (DGA) extractants, and relatively high An/Ln separation efficiencies have been obtained using diethylenetriamine-N,N’,N”-triacetic acid-N,N”-bis(diethylacetamide) (DTBA). Referring to our previous study, where a good separation and a MA recovery of approximately 95% with the co-existence of 5% Nd in the aqueous phase were observed. To improve these results as well as the separation conditions, under modified conditions by adding lactic acid to stabilize pH, the recovery rates observed were as follows: 97.1% for average Ln metals with the co-existence of 1.59% Am in the organic phase and 98.4% for Am with the co-existence of 2.95% Ln in the aqueous phase.