Selective crystallization of dysprosium complex from neodymium/dysprosium mixture enabled by cooperation of coordination and crystallization

Masuya-Suzuki, Atsuko; Hosobori, Koji; Sawamura, Ryota; Abe, Y.; Karashimada, Ryunosuke; Iki, Nobuhiko

doi:10.1039/d1cc06174g

Cited by 7 publications

(13 citation statements)

References 42 publications

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“…Overall, this apparently small structural difference between the Nd and Dy complexes led to a significant solubility difference between complexes [Nd(Trensal p ‑OMe )(H 2 O)] and [Dy(Trensal p ‑OMe )] in acetone. The separation capabilities achieved with the use of the Trensal p ‑OMe ligand in a one-pot reaction and very mild conditions are good and confirmed the effectiveness previously demonstrated on similar systems . Optimization steps are nevertheless required to improve the metal separations for a potential scale-up process.…”

Section: Discussionsupporting

confidence: 73%

“…Treatment of the spectral data using the HypSpec2014 software allowed us to determine the values of the logarithms of the formation constants ( K ) of the 1:1 Nd/L and Dy/L complexes, which were 7.0(2) and 7.3(2), respectively. These values are 1 to 2 log units higher than those determined by Masuya-Suzuki et al, who reported the formation constants in dimethyl sulfoxide for Dy and Nd complexes with Trensal p ‑Me . Indeed, acetone exhibits a weaker solvation effect toward the metals with respect to dimethyl sulfoxide, thus explaining the larger values of K in acetone.…”

Section: Resultscontrasting

confidence: 60%

“…We have interpreted these changes with hydrolysis of the Shiff base groups and have excluded water as a possible solvent for further studies of these systems. Accordingly, previous studies by Masuya-Suzuki et al on Trensal p ‑Me were performed in dried DMSO/isopropyl alcohol mixtures . From a screening of various organic solvents, acetone was selected for the separation experiments because all of the ligands were highly soluble in it, and the stock solutions were stable for at least up to a month in a nondry environment (Figure S13).…”

Section: Resultsmentioning

confidence: 99%

“…These features allow for a slight, but significant, ability to adapt to the metal requirements (ion size and geometry) while preserving its full coordination properties. In a previous work, the effective Nd/Dy separation was investigated by using Trensal p ‑Me as a chelating ligand . The slight difference in the stability constants between the Nd and Dy complexes was assessed as a reasonable explanation for their separation.…”

Section: Introductionmentioning

confidence: 99%

“…In a previous work, the effective Nd/Dy separation was investigated by using Trensal p -Me as a chelating ligand. 53 The slight difference in the stability constants between the Nd and Dy complexes was assessed as a reasonable explanation for their separation. However, the cited work did not report detailed structural information about the nature of the complexes, as it assumed (rightly, considering the nature of the ligand) the same isostructural seven-coordinated complexes for both metals.…”

Section: Introductionmentioning

confidence: 99%

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Semirigid Ligands Enhance Different Coordination Behavior of Nd and Dy Relevant to Their Separation and Recovery in a Non-aqueous Environment

et al. 2022

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Rare-earth elements are widely used in high-end technologies, the production of permanent magnets (PMs) being one of the sectors with the greatest current demand and likely greater future demand. The combination of Nd and Dy in NdFeB PMs enhances their magnetic properties but makes their recycling more challenging. Due to the similar chemical properties of Nd and Dy, their separation is expensive and currently limited to the small scale. It is therefore crucially important to devise efficient and selective methods that can recover and then reuse those critical metals. To address these issues, a series of heptadentate Trensalbased ligands were used for the complexation of Dy 3+ and Nd 3+ ions, with the goal of indicating the role of coordination and solubility equilibria in the selective precipitation of Ln 3+ −metal complexes from multimetal non-water solutions. Specifically, for a 1:1 Nd/Dy mixture, a selective and fast precipitation of the Dy complex occurred in acetone with the Trensal p-OMe ligand at room temperature, with a concomitant enrichment of Nd in the solution phase. In acetone, complexes of Nd and Dy with Trensal p-OMe were characterized by very similar formation constants of 7.0(2) and 7.3(2), respectively. From the structural analysis of an array of Dy and Nd complexes with Trensal R ligands, we showed that Dy invariably provided complexes with coordination number (cn) of 7, whereas the larger Nd experienced an expansion of the coordination sphere by recruiting additional solvent molecules and giving a cn of >7. The significant structural differences have been identified as the main premises upon which a suitable separation strategy can be devised with these kind of ligands, as well as other preorganized polydentate ligands that can exploit the small differences in Ln 3+ coordination requirements.

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Section: Discussionsupporting

confidence: 73%

Section: Resultscontrasting

confidence: 60%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Semirigid Ligands Enhance Different Coordination Behavior of Nd and Dy Relevant to Their Separation and Recovery in a Non-aqueous Environment

et al. 2022

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Tailoring the Use of 8‐Hydroxyquinolines for the Facile Separation of Iron, Dysprosium and Neodymium

Melegari,

Neri,

Falco

et al. 2024

ChemSusChem

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Permanent magnets (PMs) containing rare earth elements (REEs) can generate energy in a sustainable manner. With an anticipated tenfold increase in REEs demand by 2050, one of the crucial strategies to meet the demand is developing of efficient recycling methods. NdFeB PMs are the most widely employed, however, the similar chemical properties of Nd (20‐30% wt.) and Dy (0‐10% wt.) make their recycling challenging, but possible using appropriate ligands. In this work, we investigated commercially available 8‐hydroxyquinolines (HQs) as potential Fe/Nd/Dy complexing agents enabling metal separation by selective precipitation playing on specific structure/property (solubility) relationship. Specifically, test ethanolic solutions of nitrate salts, prepared to mimic the main components of a PM leachate, were treated with functionalized HQs. We demonstrated that Fe3+ can be separated as insoluble [Fe(QCl,I)3] from soluble [REE(QCl,I)4]‐ complexes (QCl,I‐: 5‐Cl‐7‐I‐8‐hydoxyquinolinate). Following that, QCl‐ (5‐Cl‐8‐hydroxyquinolinate) formed insoluble [Nd3(QCl)9] and soluble (Bu4N)[Dy(QCl)4]. The process ultimately gave a solution phase containing Dy with only traces of Nd. In a preliminary attempt to assess the potentiality of a low environmental impact process, REEs were recovered as oxalates, while the ligands as well as Bu4N+ ions, were regenerated and internally reused, thus contributing to the sustainability of a possible metal recovery process.

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Changes in nitrate binding with lanthanides in BLPhen complexes

Reddy

Ivanov

Driscoll

et al. 2023

Journal of Molecular Liquids

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Selective crystallization of dysprosium complex from neodymium/dysprosium mixture enabled by cooperation of coordination and crystallization

Abstract: Designing a molecular-level Ln3+ separation system remains a challenge for developing next-generation separation methodologies. Herein, we report crystallization-based Nd3+/Dy3+ separation using a tripodal Schiff base ligand. Highly selective crystallization of...

Cited by 7 publications

References 42 publications

Semirigid Ligands Enhance Different Coordination Behavior of Nd and Dy Relevant to Their Separation and Recovery in a Non-aqueous Environment

Semirigid Ligands Enhance Different Coordination Behavior of Nd and Dy Relevant to Their Separation and Recovery in a Non-aqueous Environment

Tailoring the Use of 8‐Hydroxyquinolines for the Facile Separation of Iron, Dysprosium and Neodymium

Changes in nitrate binding with lanthanides in BLPhen complexes

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