Separation of Am (III) by solvent extraction using water-soluble H4tpaen derivatives

Abstract

The water-soluble ligand N,N,N′,N′-tetrakis[(6-carboxypyridin-2-yl)methyl]ethylenediamine (H4tpaen) and its derivatives were synthesized and evaluated for Am/Cm separation by solvent extraction. In this context, different ligands were studied for their possible use as selective back-extraction agents of actinides, especially americium, from an organic TPH phase. The solvent consisted of different extractants mixtures (DMDOHEMA/HDEHP or TODGA/TBP systems) and was preliminarily loaded with trivalent lanthanide and actinide cations. The aim of these new water-soluble agents was to strip americium or curium in an aqueous acidic phase in order to perform their mutual separation while maintaining other cations in the organic phase. A specific ligand bearing n-alkoxy groups connected to the pyridyl rings of H4tpaen showed water solubility slightly enhanced associated with efficient back-extraction properties with the possibility to perform simultaneously inter-group separation of Am (III) from Eu (III), and intra-group separation of Am(III) from Cm(III).