Unusual Reversal in Pu and U Extraction in an Ionic Liquid Using Two Tripodal Diglycolamide Ligands: Experimental and DFT Studies

The extraction of UO2 2+ and Pu4+ ions was studied from nitric acid medium using three diglycolamide (DGA) extractants, viz. TODGA (N,N,N′,N′-tetra-n-octyldiglycolamide), T-DGA (tripodal diglycolamide), and TREN-DGA (N-pivot tripodal diglycolamide) in a molecular diluent mixture (9:1 mixture of n-dodecane and iso-decanol) and an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C4mim][Tf2N]). Using 1.0 × 10–3 M solutions of the ligands in [C4mim][Tf2N], T-DGA yielded an exceptionally high extraction of Pu4+ ion (DPu > 3.2 × 103) from 3 M HNO3 as compared to DPu values of 4 and 17 obtained with TREN-DGA and TODGA, respectively. Similarly, while the extraction of UO2 2+ ion was significantly lower than that of Am3+ ion for all the three DGA ligands in the molecular diluent and with TODGA and TREN-DGA in [C4mim][Tf2N], a reversal in the extraction trend was found in the case of T-DGA. Density Functional Theory (DFT) computational studies were carried out to understand the structures of the extracted complexes. PuL2(NO3)n (4–n)+ species with n = 2, 3, or 4 were considered for the geometry optimization. DFT data indicated longer M–O bonds with the etheric ‘O’ atom as compared to the carbonyl ‘O’ atom. The metal-ligand bond length and bond order analysis indicated the extraction of neutral complexes of the type PuL2(NO3)4 as compared to cationic species of the type PuL2(NO3)2 2+ and PuL2(NO3)3 + for all the three types of ligands (TODGA, TREN-DGA, and T-DGA)

Glycolamide-functionalized ionic liquid: Synthesis and actinide ion extraction studies

<p>A glycolamide-functionalized ionic liquid (G-FIL) was synthesized for the first time and was evaluated for the extraction of actinide ions such as Am³⁺, Pu⁴⁺ and UO₂²⁺ and fission product element ions such as Eu³⁺, Sr²⁺ and Cs⁺. The extraction of the trivalent metal ions was found to be exceptionally high at low acid concentrations, which rapidly decreased with increasing acidity. In view of the high viscosity of the G-FIL, the studies were carried out using its diluted solution in a commercial ionic liquid, <i>viz</i>. 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C₄mim][Tf₂N]).</p

Complexation of trivalent lanthanides and actinides with several novel diglycolamide-functionalized calix[4]arenes: solvent extraction, luminescence and theoretical studies

Several diglycolamide-functionalized calix[4]arenes (DGA–Calix) were evaluated for actinide extraction from acidic feeds. The ligands with four diglycolamide (DGA) pendent arms are significantly more effective extractants than those with two DGA pendent arms. The ligands have a preference for the extraction of Eu3+, a representative trivalent lanthanide ion, as compared to Am3+, a commonly encountered trivalent actinide ion. The role of organic diluents on the metal ion extraction was investigated and the results were compared with the widely studied DGA-based extractant TODGA (N,N,N′,N′-tetra-n-octyl diglycolamide). Time resolved laser fluorescence spectroscopy (TRLFS) studies showed a strong complexation with no inner-sphere water molecules in the Eu(III)–DGA–Calix complexes and the complex formation constants (log β) were calculated. Ab initio density functional calculations were carried out to explain the higher stability of the Eu-complex of the DGA–Calix ligand with four pendent arms as compared to the one with two pendent arms

Complexation of trivalent lanthanides and actinides with several novel diglycolamide-functionalized calix[4]arenes: solvent extraction, luminescence and theoretical studies

Several diglycolamide-functionalized calix[4]arenes (DGA–Calix) were evaluated for actinide extraction from acidic feeds. The ligands with four diglycolamide (DGA) pendent arms are significantly more effective extractants than those with two DGA pendent arms. The ligands have a preference for the extraction of Eu3+, a representative trivalent lanthanide ion, as compared to Am3+, a commonly encountered trivalent actinide ion. The role of organic diluents on the metal ion extraction was investigated and the results were compared with the widely studied DGA-based extractant TODGA (N,N,N′,N′-tetra-n-octyl diglycolamide). Time resolved laser fluorescence spectroscopy (TRLFS) studies showed a strong complexation with no inner-sphere water molecules in the Eu(III)–DGA–Calix complexes and the complex formation constants (log β) were calculated. Ab initio density functional calculations were carried out to explain the higher stability of the Eu-complex of the DGA–Calix ligand with four pendent arms as compared to the one with two pendent arms