An ionic liquid-based extraction system using diglycolamide functionalized macrocyclic platforms for the extraction...

Area of Science:

• Coordination Chemistry
• Separation Science
• Materials Chemistry

Background:

• Lanthanides are critical for advanced technologies, but their separation is challenging.
• Macrocyclic ligands offer tailored properties for selective metal ion complexation.
• Ionic liquids provide unique solvent properties for extraction processes.

Purpose of the Study:

• To investigate the solvent extraction of lanthanides using resorcin[4]arene- and calix[4]arene-based diglycolamide ligands.
• To evaluate the influence of ligand structure and acidity on extraction efficiency and selectivity.
• To assess the potential for selective lanthanide recovery from complex mixtures, including magnet waste.

Main Methods:

• Synthesis and characterization of resorcin[4]arene-triazole-DODGA (CR4-TZ-DODGA) and t-butylcalix[4]arene-triazole-DODGA (C4-TZ-DODGA) ligands.
• Solvent extraction experiments using N-octyl-N-ethylpiperidinium bis(trifluoromethylsulfonyl)imide ([EOPip]NTf2) as the ionic liquid phase.
• Analysis of extraction parameters using the slope method and thermodynamic studies.
• Investigation of selective extraction from a simulated rare-earth magnet leaching solution.

Main Results:

• Both CR4-TZ-DODGA and C4-TZ-DODGA effectively extracted lanthanides(III).
• Extraction efficiency varied across the lanthanide series, with a notable selectivity for Ytterbium(III) over Lanthanum(III) and Europium(III).
• Ligand concentration and acidity significantly impacted extraction performance.
• Successful selective extraction and recovery of lanthanides from a simulated magnet leaching solution were demonstrated.

Conclusions:

• The developed macrocyclic cavitand-triazole-diglycolamide ligands are effective for lanthanide extraction in ionic liquids.
• These ligands exhibit promising selectivity for heavier lanthanides, enabling potential applications in rare-earth element separation and recycling.
• The study highlights the utility of functionalized macrocycles in ionic liquid systems for critical metal recovery.