Effect of diluent on the extraction of europium(iii) and americium(iii) with N, N, N', N'-tetraoctyl diglycolamide (TODGA)

Ivan Kajan; Markéta Florianová; Christian Ekberg; Artem V Matyskin

doi:10.1039/d1ra07534a

Effect of diluent on the extraction of europium(iii) and americium(iii) with N, N, N', N'-tetraoctyl diglycolamide (TODGA)

RSC Adv. 2021 Nov 16;11(58):36707-36718. doi: 10.1039/d1ra07534a. eCollection 2021 Nov 10.

Authors

Ivan Kajan¹, Markéta Florianová², Christian Ekberg³, Artem V Matyskin³

Affiliations

¹ Laboratory of Radiochemistry, Paul Scherrer Institute 5232 Villigen Switzerland ivan.kajan@psi.ch.
² Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University Brehova 7 11519 Prague 1 Czech Republic.
³ Nuclear Chemistry and Industrial Material Recycling Group, Department of Chemistry and Chemical Engineering, Chalmers University of Technology 41296 Gothenburg Sweden.

Abstract

Solvent extraction of Eu³⁺ and Am³⁺ via N,N,N',N'-tetraoctyl diglycolamide (TODGA) dissolved in different molecular diluents was studied. The diluent types used in this work were primary and secondary alcohols, secondary ketones and alkanes. Effects of concentration of extracting agent, temperature, diluent type and its carbon chain length on the extractions were determined. Distribution ratios of Eu³⁺ and Am³⁺ showed high dependence on the diluent type as well as the carbon chain length within the same type of diluent. The highest distribution ratios for both Eu³⁺ and Am³⁺ as well as the separation factors of Eu³⁺ over Am³⁺ were observed in the alkane diluents. Unexpectedly high distribution ratios for Eu³⁺ and Am³⁺ were observed in polar diluents with 5 carbon atoms in the chain, clearly standing out against the general trends. It was found that Eu³⁺ and Am³⁺ extraction via TODGA is enthalpy driven in all the studied diluents and that extraction is more exothermic in alkane diluents. Analysis of the stoichiometry of the extracted complexes shows that the average ligand number of TODGA molecules in the extracted complex is lower for Am³⁺ compared to Eu³⁺ except for with alkane diluents.