Evaluation of selected solvent systems for the single-cycle separation of Am(III) from Eu(III) using aqueous soluble sulphonated bis-triazinylpyridine

Abstract

Abstract The process methods developed for partitioning of trivalent actinides from high-level liquid waste (HLLW) are being focussed on single-cycle processing approaches. This method involves the separation of trivalent actinides and chemically similar lanthanides, as a group, from HLLW followed by the mutual separation of lanthanides and actinides from the loaded organic phase using aqueous soluble complexing agents. The potential solvents identified for the group separation of trivalents from HLLW are 1) 0.2 M TODGA (N,N,N’N′-tetraoctyldiglycolamide) + 5% octanol / n-DD, 2) 0.2 M TODGA + 0.5 M TBP (tri-n-butylphosphate) / n-DD, 3) 0.1 M TODGA + 0.25 M HDEHP (di-(2-ethylhexyl)phosphoric acid) / n-DD, 4) 0.2 M TDDGA (N,N,N’N′-tetradecyldiglycolamide) / n-DD, 5) 0.2 M D3DODGA (N,N-didodecyl-N’N′-dioctyldiglycolamide) / n-DD, 6) 0.4 M DOHyA (N,N-dioctyl-2-hydroxyacetamide) / n-DD. The extraction behaviour of Am(III) and Eu(III) from dilute nitric acid solution (0.1 M to 1 M) containing aqueous soluble nitrogen-donor derivative, SO3-Ph-BTP, was studied in the above solvents. The separation factor (SF) of Eu(III) over Am(III) was determined. Among the different solvents investigated, the SF achieved in TDDGA and D3DODGA was quite higher than other solvents, and recommended for the single-cycle separation of trivalent actinides from HLLW.