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

Insight into the Complexation of Actinides and Lanthanides with Diglycolamide Derivatives: Experimental and Density Functional Theoretical Studies

Extraction of actinide (Pu⁴⁺, UO₂²⁺, Am³⁺) and lanthanide (Eu³⁺) ions was carried out using different diglycolamide (DGA) ligands with systematic increase in the alkyl chain length from <i>n</i>-pentyl to <i>n</i>-dodecyl. The results show a monotonous reduction in the metal ion extraction efficiency with increasing alkyl chain length and this reduction becomes even more prominent in case of the branched alkyl (2-ethylhexyl) substituted DGA (T2EHDGA) for all the metal ions studied. Steric hindrance provided by the alkyl groups has a strong influence in controlling the extraction behavior of the DGAs. The distribution ratio reduction factor, defined as the ratio of the distribution ratio values of different DGAs to that of T2EHDGA, in <i>n</i>-dodecane follows the order UO₂²⁺ > Pu⁴⁺ > Eu³⁺ > Am³⁺. Complexation of Nd³⁺ was carried out with the DGAs in methanol by carrying out UV–vis spectrophotometric titrations. The results indicate a significant enhancement in the complexation constants upon going from methyl to <i>n</i>-pentyl substituted DGAs. They decreased significantly for DGAs containing alkyl substituents beyond the <i>n</i>-pentyl group, which corresponds to the observed trend from the solvent extraction studies. DFT-based calculations were performed on the free and the Nd³⁺ complexes of the DGAs both in the gas and the solvent (methanol) phase and the results were compared the experimental observations. Luminescence spectroscopic investigations were carried out to understand the complexation of Eu³⁺ with the DGA ligands and to correlate the nature of the alkyl substituents on the photophysical properties of the Eu­(III)-DGA complexes. The monoexponential nature of the decay profiles of the complex revealed the predominant presence of single species, while no water molecules were present in the inner coordination sphere of the Eu³⁺ ion

First Report on the Separation of Trivalent Lanthanides from Trivalent Actinides Using an Aqueous Soluble Multiple N‑Donor Ligand, 2,6-bis(1<i>H</i>‑tetrazol-5-yl)pyridine: Extraction, Spectroscopic, Structural, and Computational Studies

A terdentate multiple N donor ligand, 2,6-bis­(1<i>H</i>-tetrazol-5-yl)­pyridine (H₂BTzP), was synthesized, and its complexation with trivalent americium, neodymium, and europium was studied using single-crystal X-ray diffraction, attenuated total reflectance-fourrier transform infrared spectroscopy, time-resolved fluorescence spectroscopy, UV–vis absorption spectrophotometry. Higher complexation strength of BTzP toward trivalent actinide over lanthanides as observed from UV–vis spectrophotometric study resulted in an effective separation of Am³⁺ and Eu³⁺ in liquid–liquid extraction studies employing <i>N,N,<i>N</i>′,N′</i>-tetra-<i>n</i>-octyl diglycolamide in the presence of BTzP as the aqueous complexant. The selectivity of BTzP toward Am³⁺ over Eu³⁺ was further investigated by DFT computations, which indicated higher metal–ligand overlap in the Am³⁺ complex as indicated from the metal–nitrogen bond order and frontier molecular orbital analysis of the BTzP complexes of Am³⁺ and Eu³⁺

Highly Efficient Extraction Chromatography Resin Containing Hexa‑<i>n</i>‑Octyl Nitrilotriacetamide (HONTA) for Selective Recovery of Plutonium from Acidic Feeds

An extraction chromatography resin was prepared by impregnating hexa-n-octyl nitrilotriacetamide (HONTA) on chromosorb-W. This resin shows very efficient performance for selective separation of Pu4+ over other actinides like uranium and americium. The distribution coefficient for Pu4+ (at 3 M HNO3) was on the order of 104 mL/g, with separation factors of >103 for other actinides. The extraction kinetics for Pu4+ was slow and took 20 min of shaking for reaching the equilibrium conditions and followed both the film diffusion and the intraparticle diffusion kinetic models. The Pu4+ sorption on the resin followed the Langmuir monolayer model with a sorption energy of 11.2 kJ/mol. The maximum Pu4+ loading capacity on the resin was 58.2 mg/g resin, which corresponds to 1:1 Pu/ligand complex formation. Excellent column performance was observed for selective separation of Pu4+ from a mixture of Pu, Am, and U in a 3 M HNO3 solution