Highly efficient extraction separation of lanthanides using a diglycolamic acid extractant.

Area of Science:

• Inorganic Chemistry
• Separation Science
• Coordination Chemistry

Background:

• Lanthanide ion (Ln(3+)) separation is crucial for various industrial applications.
• Developing efficient and selective extractants for Ln(3+) remains a significant challenge.
• N,N-dioctyldiglycolamic acid (DODGAA) is a novel ligand with potential for Ln(3+) extraction.

Purpose of the Study:

• To investigate the liquid-liquid extraction of Ln(3+) using DODGAA.
• To characterize the extracted Ln(3+)-DODGAA complexes.
• To evaluate the separation performance of DODGAA for lanthanides.

Main Methods:

• Liquid-liquid extraction experiments.
• Fluorescence spectroscopy for complex characterization.
• Slope analysis and loading tests for mechanism determination.
• Electrospray ionization mass spectrometry (ESI-MS).
• Time-resolved laser-induced fluorescence spectroscopy.

Main Results:

• DODGAA quantitatively extracts all Ln(3+) ions from moderately acidic solutions.
• DODGAA exhibits selectivity for heavier lanthanides and superior separation performance over carboxylic acids.
• Mutual separation of light lanthanides by DODGAA surpasses organophosphorus extractants.
• Proton-exchange mechanism confirmed, forming a 1:3 complex (Ln(DODGAA)3).
• Successful stripping of Ln(3+) under acidic conditions.
• Extracted Eu(3+) ions are completely dehydrated upon complexation.

Conclusions:

• DODGAA is a highly effective extractant for lanthanide ions, offering excellent separation factors.
• The 1:3 complexation mechanism and complete dehydration of extracted ions highlight DODGAA's unique properties.
• DODGAA presents a promising alternative to existing extractants for lanthanide separation technologies.