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.

KEYWORDS:

• Lanthanide
• Am
• TODGA
• solvent extraction
• organic acid

Acknowledgments

The authors gratefully acknowledge Drs. M. Watanabe and R. Kusaka of the Research Group for Radiochemistry at JAEA for managing the laboratory and ensuring its safety, Drs. K. Morita, T. Matsutani, and Y. Ban at JAEA for providing useful discussion regarding the use of mixer-settlers, and Dr. Kosai and Ms. Kaneda at JAEA for the use of elemental analysis.

This study was partially supported by a Grant-in-Aid for Scientific Research (No. 18H03404) from Ministry of Education, Culture, Sports, Science and Technology, Japan.

Disclosure statement

No potential conflict of interest was reported by the author(s).

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