The Partitioning of Americium and the Lanthanides Using Tetrabutyldiglycolamide (TBDGA) in Octanol and in Ionic Liquid Solution

Abstract

Separations among the lanthanides and the separation of Am from the lanthanides remain challenging, and research in this area continues to expand. The separation of adjacent lanthanides is of interest to high-tech industries because individual lanthanides have specialized uses and are in short supply. In nuclear fuel cycle applications Am would be incorporated into fast-reactor fuels, yet the lanthanides are not desired. In this work, the diglycolamide N,N,N′,N′-tetrabutyldiglycolamide (TBDGA) was investigated as a ligand for lanthanide and Am solvent extraction in both molecular and room-temperature-ionic-liquid (RTIL) diluents.The RTIL [C₄MIM][Tf₂N] showed very high extraction efficiency for these trivalent metals from low nitric acid concentrations, while the molecular diluent 1-octanol showed high extraction efficiency at high acid concentrations. This was attributed to the extraction of ionic nitrate complexes by the RTIL, whereas 1-octanol extracted neutral nitrate complexes. TBDGA in RTIL did not provide adequate separation factors for Am/lanthanide partitioning, but 1-octanol did show reasonable separation possibilities. Lanthanide intergroup separations appeared to be feasible in both diluents, but with higher separation factors from 1-octanol.

Keywords:

• Americium
• lanthanides
• ionic liquids
• diglycolamides

ACKNOWLEDGMENTS

This work was partially supported by DOE-NEUP grant (TO 00058), and the work was performed under DOE Idaho Operations Office Contract DE-AC07-05ID14517. The authors thank D. Peterman for helpful discussions.