Sequestration of tetravalent neptunium from acidic feeds using diglycolamide-functionalized dendrimers in a room temperature ionic liquid: extraction, spectroscopic and electrochemical studies

Abstract

Quantitative extraction of Np(IV) was achieved using a room temperature ionic liquid containing submillimolar concentrations of two poly(propyleneimine) based dendrimer ligands with four (LI) and eight diglycolamide (DGA) moieties (LII)...

Extraction of Np(IV/VI) from nitric acid medium using three different tripodal diglycolamide ligands in ionic liquid: Batch extraction, spectroscopic and electrochemical investigations

“…The decrease in the D Np(IV) -value with the aqueous feed acidity up to 1 M HNO 3 for L I suggests a 'cation-exchange' mechanism for Np(IV) extraction in the 0.5 to 1 M HNO 3 acidity range. This was also observed by Verma et al for a DGA dendrimer in C 4 mimNTf 2 in the 0.5 to 4 M HNO 3 acidity range [24].…”

“…Out of the various ligands employed for Np separation from acidic feeds, those involving diglycolamides (DGA) have been found to be quite efficient [14,[18][19][20][21][22][23][24]. In a subsequent development, multiple-DGA ligands were found to be significantly more promising than the commonly employed simple DGA ligands such as TODGA (N,N,N',N'-tetra-n-octyl diglycolamide).…”

“…In a subsequent development, multiple-DGA ligands were found to be significantly more promising than the commonly employed simple DGA ligands such as TODGA (N,N,N',N'-tetra-n-octyl diglycolamide). Though there are several classes of multiple-DGA ligands such as those anchored onto calix [4]arene [21,25,26], pillar [5]arene [27] and dendritic [24,28,29] scaffolds, the tripodals have been really interesting as they can afford nine donor atoms from the six amidic and three etheric 'O' atoms, which can easily satisfy the coordination numbers of the trivalent / tetravalent actinide ions. We have employed several multiple DGA ligands for the extraction of Np from acidic feed solutions [21,22,24,28,30,31] out of which the tripodal DGA ligands (Fig.…”

“…Np tracer ($10 -12 M) was prepared by a standard method reported before [24,36]. For this purpose, about 2 mg of solid UO 2 (-NO 3 ) 2 was irradiated in the Dhruva reactor at a neutron flux of 5 Â 10 13 n/cm 2 /s for about 5 days and the activated product ( 239 Np) was separated using the reported TTA (2-thenoyl trifluoroacetone) extraction method [21,40].…”

Sequestration of Np(IV) and Pu(IV) with Hexa-n-octyl nitrilotriacetamide (HONTA) in an Ionic Liquid: Unusual Species vis-à-vis a Molecular Diluent

“…Cyclic voltammetry (CV) studies were conducted in a three-electrode system consisting of two Pt-disk electrodes (2 mm diameter each) as the working and the reference electrodes, respectively, while a Pt-wire was used as the counter electrode at room temperature (298 K) using the AUTOLAB electrochemical setup by Metrohm. The choice of the working, reference, and counter electrodes was based on our previous studies with similar systems. − The organic extract of 237 Np­(IV) was obtained by equilibrating it in a 0.5 M HNO 3 + 2.5 M NaNO 3 aqueous mixture with 1 mM HONTA in C 4 mim·NTf 2 . Since the electrochemical measurements required a relatively large concentration of the metal ion, we used 237 Np ( t 1/2 = 2.1 × 10 6 y) for this work.…”