Investigation of Sr²⁺ Extraction from Aqueous Phase Using Novel Diglycolamide/Ionic Liquid System.

Area of Science:

• Nuclear Chemistry
• Radiochemistry
• Separation Science

Background:

• High-purity strontium-90 (Sr-90) is essential for the Sr-90/Y-90 generator, a key medical isotope source.
• Current methods for recovering Sr-90 from high-level liquid waste (HLLW) often yield products with insufficient purity.

Purpose of the Study:

• To develop a novel extraction system for achieving high-purity Sr-90 from HLLW.
• To integrate this system with existing separation processes for enhanced efficiency.

Main Methods:

• Design and synthesis of a novel diglycolamide (DGA) ligand, N,N-diphenyl-N',N'-dibutyl diglycolamide (DPDBDGA).
• Evaluation of various diluents, selecting 1-butyl-3-methylimidazolium bis(trifluoromethanesulphonyl)imide ([C4mim][NTf2]) as optimal.
• Optimization of extraction parameters including nitric acid and ligand concentrations.
• Investigation of the extraction mechanism and stoichiometry using slope analysis and ESI-MS.

Main Results:

• The novel DPDBDGA ligand in [C4mim][NTf2] demonstrated efficient Sr2+ extraction via cation exchange mechanisms.
• A 1:3 complex between Sr2+ and the DPDBDGA ligand was identified.
• [C4mim][NTf2] proved to be a highly effective diluent for Sr2+ extraction.

Conclusions:

• The developed DGA ligand and ionic liquid system provides a viable method for producing high-purity Sr-90.
• This system is compatible with existing separation processes, offering a pathway to improved Sr-90 recovery from HLLW.