Effect of Diglycolamide Ligands Structure on Extraction Performance of Heavy Rare Earth Ions

Du, Huihui; Peng, Xiujing; Cui, Yu; Sun, Guoxin

doi:10.15261/serdj.27.81

Cited by 8 publications

(7 citation statements)

References 24 publications

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“…These variables include better defining the role of the phase transfer catalysts, the impact of metal contaminants present in solution on 241 Am extraction, extraction capacity for the CMPO , and DGA , extraction resins, etc. This study, and those preceding in the literature, ,,,,− ,− will hopefully inspire innovative research in the future that improves our general understanding of extraction chromatography. If successful, further optimizing large-scale separations for 241 Am recovery, and for processing other important analytes, will be more easily realized.…”

Section: Discussionmentioning

confidence: 70%

Characterizing Extraction Chromatography for Large-Scale Americium-241 Processing

Arko

Dan

Adelman

et al. 2021

Ind. Eng. Chem. Res.

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The americium-241 ( 241 Am) radioisotope has valuable nuclear properties that find broad industrial usage. Ensuring stable supplies of 241 Am is critical for supporting (and expanding) the existing 241 Am-application space and enabling emerging 241 Amtechnologies that are important for economic growth, energy, and national security. Unfortunately, the United States halted 241 Am production in 1984 and the existing inventory was depleted in the early 2000s. This situation recently changed when the U.S. Department of Energy Isotope Program established 241 Am recovery at Los Alamos National Laboratory. Today, large-scale quantities of 241 Am are now obtained using the Chloride Extraction and Actinide Recovery (CLEAR) process. This method uses a resin that has the di-(4-t-butylphenyl)-N,N-di-iso-butylcarbamoylmethylphosphine oxide (m-CMPO) extractant adsorbed on a resin bead to harvest 241 Am from plutonium-containing waste streams. To maintain and improve CLEAR processing of 241 Am, we have evaluated the extraction of 241 Am by m-CMPO as a function of three important processing relevant variables: (1) HCl concentration, (2) metal contaminant concentration, and (3) contact time. The performance of the m-CMPO resin was additionally compared against commercially available resins, namely, rare earth (RE) resin and a selected series of diglycolamide (DGA) resins. Our results suggested that the m-CMPO resin outperformed most of the commercially available alternatives. However, tetraoctyl-DGA (TODGA) and tetraethyl-hexyl-DGA (TEHDGA) prevailed on several fronts. The TODGA and TEHDGA resins quantitatively released 241 Am at low HCl concentrations (<0.5 M), were less susceptible to deleterious side effects from metal contaminants in the mobile phase and bound 241 Am faster. Based on these results, we concluded that 241 Am recovery yields have the potential to improve if TODGA or TEHDGA is used in place of m-CMPO for large-scale CLEAR processing of 241 Am.

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Section: Discussionmentioning

confidence: 70%

Characterizing Extraction Chromatography for Large-Scale Americium-241 Processing

Arko

Dan

Adelman

et al. 2021

Ind. Eng. Chem. Res.

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“…The signal intensity increased with increasing concentration of the metal ions from 10 –3 to 10 2 mM. Based on the band position and structure of the DGA ligand, the signals at ∼1630 cm –1 can be attributed mainly to the CO stretching vibration . The positive and negative signals correspond to the absorption of the DGA complexes and uncomplexed DGA, respectively.…”

Section: Results and Discussionmentioning

confidence: 96%

“…Based on the band position and structure of the DGA ligand, the signals at ∼1630 cm −1 can be attributed mainly to the C�O stretching vibration. 20 The positive and negative signals correspond to the absorption of the DGA complexes and uncomplexed DGA, respectively. The positive band was found on the low-frequency side of the negative one, indicating the red shift of the C�O stretching band of DGA upon complex formation with the M 3+ ions.…”

Section: Resultsmentioning

confidence: 99%

“…Similar results of red shifts upon complex formation were reported for the complexes of DGA derivatives with heavy metal ions in solution. 20 However, these IR spectra were observed only for Yb 3+ , and it was unclear whether IR spectroscopy could distinguish between the ions captured by organic ligands. The SEIRA results in this study clearly demonstrate the usefulness of IR spectroscopy for investigating the structures of ion complexes based on the coordination ability of the ligands.…”

Section: Resultsmentioning

confidence: 99%

“…To efficiently separate Ln and An, organic ligands used in solvent extraction should have a higher selectivity toward either Ln or An. However, the ionic radii of Ln and An are similar and hence make efficient separation substantially difficult. , In the last three decades, numerous efforts have been devoted to the development of effective extractants for separating Ln and An ions. ,− In these studies, the affinity of the extractants toward Ln and An was evaluated mainly by the extraction equilibrium constant from the aqueous to organic phases during solvent extraction; however, the origin of this high coordination ability was not discussed from a molecular science point of view. Previous reports on the separation of Ln and An suggest that O-donor ligands, such as N , N , N′ , N′ -tetraalkyldiglycolamide (TADGA) and Cyanex-272, preferentially bind with Ln over An, whereas N-donor ligands such as N , N , N′ , N′ -tetrakis(2-methylpyridyl)ethylenediamine (TPEN) bind predominantly with An. ,− The electrostatic interactions between organic ligands and the Ln/An ions could be similar owing to their similar ionic radii .…”

Section: Introductionmentioning

confidence: 99%

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Lanthanide and Actinide Ion Complexes Containing Organic Ligands Investigated by Surface-Enhanced Infrared Absorption Spectroscopy

et al. 2022

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A new technique, surface-enhanced infrared absorption (SEIRA) spectroscopy, was used for the structural investigation of lanthanide (Ln) and actinide (An) complexes containing organic ligands. We synthesized thiol derivatives of organic ligands with coordination sites similar to those of 2-[N-methyl-N-hexanethiol-amino]-2-oxoethoxy-[N′,N′-diethyl]-acetamide [diglycolamide (DGA)], Cyanex-272, and N,N,N′,N′-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN), which have been used for separating Ln and An through solvent extraction. These ligands were attached on a gold surface deposited on an Si prism through S–Au covalent bonds; the gold surface enhanced the IR absorption intensity of the ligands. Aqueous solutions of Ln (Eu3+, Gd3+, and Tb3+) and An (Am3+) ions were loaded onto the gold surface to form ion complexes. The IR spectra of the ion complexes were obtained using Fourier transform infrared spectroscopy in the attenuated total reflection mode. In this study, we developed a new sample preparation method for SEIRA spectroscopy that enabled us to obtain the IR spectra of the complexes with a small amount of ion solution (5 μL). This is a significant advantage for the IR measurement of radiotoxic Am3+ complexes. In the IR spectra of DGA, the band attributed to CO stretching vibrations at ∼1630 cm–1 shifted to a lower wavenumber by ∼20 cm–1 upon complexation with Ln and An ions. Moreover, the amount of the red shift was inversely proportional to the extraction equilibrium constant reported in previous studies on solvent extraction. The coordination ability of DGA toward Ln and An ions could be assessed using the band position of the CO band. The Cyanex-272- and TPEN-like ligands synthesized in this report also showed noticeable SEIRA signals for Ln and An complexes. This study indicates that SEIRA spectroscopy can be used for the structural investigation of ion complexes and provides a microscopic understanding of selective extraction of Ln and An.

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Elucidating the speciation of extracted lanthanides by diglycolamides

Peroutka

Galley

Shafer

2023

Coordination Chemistry Reviews

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Effect of Diglycolamide Ligands Structure on Extraction Performance of Heavy Rare Earth Ions

Cited by 8 publications

References 24 publications

Characterizing Extraction Chromatography for Large-Scale Americium-241 Processing

Characterizing Extraction Chromatography for Large-Scale Americium-241 Processing

Lanthanide and Actinide Ion Complexes Containing Organic Ligands Investigated by Surface-Enhanced Infrared Absorption Spectroscopy

Elucidating the speciation of extracted lanthanides by diglycolamides

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