A Simple yet Efficient Hydrophilic Phenanthroline-Based Ligand for Selective Am(III) Separation under High Acidity

Area of Science:

• Nuclear Chemistry
• Materials Science
• Separation Science

Background:

• Liquid-liquid extraction (LLE) for lanthanide (Ln(III)) and actinide (An(III)) separation traditionally relies heavily on hazardous organic solvents.
• Existing hydrophilic ligands often exhibit poor performance, limited structural diversity, and low acid tolerance, hindering efficient separation processes.

Purpose of the Study:

• To develop a novel hydrophilic ligand with enhanced selectivity and acid resistance for Ln(III)/An(III) separation.
• To investigate the structural basis for the ligand's superior separation capabilities and acid tolerance.

Main Methods:

• Synthesis of a carboxylic group modified phenanthroline-diimide ligand.
• Evaluation of the ligand's performance in liquid-liquid extraction of Ln(III) and An(III) under high acidity (1.5 M HNO3).
• Crystallographic analysis of lanthanide complexes to elucidate structural features.

Main Results:

• The novel ligand demonstrated unexpected high selectivity for Lns(III)/Ans(III) and Ans(III)/Ans(III) separation in 1.5 M HNO3.
• Unique dimeric architectures of Europium(III) complexes were observed, correlating with enhanced selectivity and acid resistance.
• The ligand overcomes limitations of previously reported hydrophilic extractants.

Conclusions:

• A simple, efficient carboxylic group modified phenanthroline-diimide ligand offers a promising solution for selective Ln(III)/An(III) separation under harsh acidic conditions.
• The observed dimeric structures highlight the potential of crystal engineering in designing advanced separation ligands.
• This approach could revitalize the search for new functional groups and coordination strategies for high-acid-tolerance separation applications.