Selective Complexation and Separation of Tetravalent Metal Ions from Other Ions

APPLICATIONS OF TECHNOLOGY:

Nuclear energy or nuclear fuel reprocessing plants
Pharmaceutical isotope production
Pharmaceutical companies using lanthanide or actinide drugs
Chemical industry

ADVANTAGES:

Highly selective
Improved performance and reliability
Versatile process
Fewer steps

ABSTRACT:

Berkeley Lab researchers Rebecca Abergel and Gauthier Deblonde have developed a technology in which an aqueous chelator, 1,2-HOPO, binds tetravalent metal ions in a very selective manner under highly acidic conditions for purification of tetravalent metal ions from other ions (not exhibiting a 4+ charge). This invention is part of a suite of HOPO-based separations applicable to the nuclear and pharmaceutical industries. For example, in nuclear fuels recycling and medical isotope production, ions exhibiting different charges in a mixture must be separated to obtain a final product.

The Berkeley Lab researchers have demonstrated that 1,2-HOPO stays bound to tetravalent hafnium (Hf⁴⁺) and zirconium (Zr⁴⁺) ions from pH 11 to 6M H₃O⁺, at a minimum. In the case of tetravalent titanium (Ti⁴⁺) and tin (Sn⁴⁺), the metals stay bound to the chelator from pH 6 to 6M H₃O⁺ and from pH 8 to 1M H₃O⁺, respectively. Based on thermodynamic data, the researchers expect tetravalent plutonium, thorium, and cerium (Pu⁴⁺, Th⁴⁺, and Ce⁴⁺) to behave similarly.

In addition, 1,2-HOPO releases trivalent and divalent metal ions as soon as pH drops below 1, offering a powerful leverage for separation and purification.

The separation of tetravalent ions bound to the chelator from unbound ions can be achieved using a non-selective extractant and performing a liquid-liquid extraction step. The tetravalent ions stay in the aqueous phase, and the rest is extracted in the organic phase. Both high-purity tetravalent and trivalent ions can be obtained.

Classical aqueous chelators are chemically unable to complex metal ions under highly acidic conditions seen in typical nuclear fuel and medical isotope applications. Thus, the separation of metal ions relies on the (usually poor) selectivity of the extractant or of a solid support. The Berkeley Lab invention overcomes this limitation, enabling simpler and more efficient industrial processes for the separation and purification of metal ions.

DEVELOPMENT STAGE: Proven principle

FOR MORE INFORMATION:
Rees, J., Deblonde, G., An, D., Ansoborio, C., Gauny, S., and Abergel, R. Evaluating the potential of chelation theapy to prevent and treat gadolinium deposition from MRI contrast agents, Nature Scientific Reports (2018) 8:4419.

STATUS: Published PCT Patent Application US2017/048934 (Publication WO/2018/097871). Available for licensing or collaborative research.

SEE THESE OTHER BERKELEY LAB TECHNOLOGIES IN THIS FIELD:

HOPO Ligands to Separate and Purify Metal Ions including Lanthanides and Actinides, 2017-106

Decorporation Agent for Therapeutic Chelation of Industrial and Clinical Toxic Heavy Metals 2016-078

Oral Dosage Forms for Actinide Decorporation Agent 2016-079