Highly Promising Method for the Decontamination of Europium from Americium Using an Extraction Chromatography Resin Containing a Tripodal Diglycolamide and SO₃Ph-BTP as Eluent

Abstract

Separation of Am3+ from Eu3+ was demonstrated by extraction column chromatography using a tripodal diglycolamide ligand (T-DGA). A clean separation was achieved by selective complexation of Am3+ in the feed with 2,6-bis­(5,6-di­(sulfophenyl)-1,2,4-triazin-3-yl)­pyridine (SO3Ph-BTP) with a separation factor of about 2000. The extraction chromatography resin material with particle size in the range of 175–250 μm contained only 7.4% T-DGA ligand (53 μmol/g) and is one of the most efficient materials used for this purpose until date. Parameters such as feed acidity and SO3Ph-BTP concentration were varied, while keeping the other parameters constant for getting the best optimized condition for the separation of Am3+ from Eu3+ ions. The optimized feed condition was 0.1 M HNO3 containing 10 mM SO3Ph-BTP for the clean separation of Am3+ from the Eu3+ fraction. In the feed solution containing Eu3+ and Am3+, the latter was complexed with SO3Ph-BTP and, therefore, was not retained on the column, whereas the uncomplexed Eu3+ could be efficiently held onto the column. Finally, the loaded Eu3+ from the column was eluted with 0.1 M HEDTA (N-(2-hydroxyethyl)­ethylenediamine-N,N′,N′-triacetic acid), giving a sharp and narrow elution curve. The radiation stability of the resin was excellent up to 1000 KGy gamma dose, and an identical separation efficiency of the resin was noted with the irradiated resin column, as was obtained with the pristine resin.

First Report on a 1-Cycle Solid-Phase Extraction Method for Selective Separation of Am3+ and Eu3+: Use of BTP-Grafted Silica Decorated on Activated Carbon

“…The K d values for Am 3+ decreased continuously with increasing feed acidity, which is typical for the BTP-based ligands. − The BTP based on ligands has higher basicity due to the presence of nitrogen donor atoms; therefore, at higher acidity, these ligands are protonated and lose their coordination efficiency. For this reason, the BTP class of ligands is preferentially used at lower acidities . Additionally, due to the preferential affinity of BTP ligands for the trivalent actinides over their lanthanide counterparts, the material used in this work also showed preferential extraction of Am 3+ over Eu 3+ .…”

“…The optimized aqueous-phase condition was 0.2 M HNO 3 , and therefore, all subsequent studies were performed at this feed acidity. We have recently used the SO 3 PhBTP ligand for the selective stripping of Am 3+ from an extraction chromatography resin containing T-DGA (a tripodal multiple diglycolamide ligand), and the optimized feed was 0.01 M HNO 3 + 0.01 M SO 3 Ph-BTP, which is in good agreement with the present results.…”

“…However, the 241 Am fraction showed very marginal contamination with the 152 Eu activity, as confirmed by gamma-ray spectrometry (Figure ). A similar clean separation of Am and Eu was reported recently by us using a T-DGA-based extraction chromatography column onto which both the metal ions were loaded initially, followed by elution of Am by the SO 3 PhBTP solution in 0.1 M HNO 3 . This suggests the great potential of BTP as a complexing agent for either selective loading (as in the present case) or elution of Am from a mixture containing Am + Eu.…”

“…The results showed the highest selectivity in 0.2 M HNO 3 with an SF value >100 for Am 3+ over Eu 3+ , which is one of the very good reports for this purpose using a solid-phase material. The advantage of the method is a 1-cycle separation compared to the 2-cycle separation reported previously with an extraction chromatography resin containing a tripodal diglycolamide ligand . Fitting of the adsorption isotherm of Eu 3+ on this solid material showed that it follows the Langmuir model of sorption.…”

“…As represented in Figure , the aim of the present work is to selectively load Am 3+ onto the AC–Si–BTP composite material making it a direct 1-cycle separation process with the BTP-based compound in the same way Cyanex 301-based solid-phase extraction materials reported in the literature . The only BTP-based solid-phase extraction method for Ln–An separation was extraction chromatography using a tripodal diglycolamide (T-DGA), which used an aqueous soluble BTP (SO 3 PhBTP) as the complexing eluent, making it a 2-cycle separation process …”