Separation of uranium(VI) and americium(III) by Extraction from Na₂CO₃–H₂O₂ solutions using methyltrioctylammonium carbonate in toluene

ABSTRACT

Liquid–liquid extraction of carbonate and mixed peroxo-carbonate compounds of U(VI) and Am(III) from Na₂CO₃ aqueous solutions by methyltrioctylammonium carbonate in toluene has been studied. The main patterns of effect of extractant, Na₂CO₃, and H₂O₂ concentration on distribution and separation of U(VI) and Am(III) have been established. Using slope analysis and UV–vis spectroscopy, the compositions of U(VI) and Am(III) extractable compounds are established as (R₄N)₄[UO₂(CO₃)₃], (R₄N)₄[UO₂(О₂)(CO₃)₂], and (R₄N)₆[(UO₂)₂(O₂)(CO₃)₄] for U(VI); R₄N[Am(CO₃)₂] and (R₄N)₃[Am(CO₃)₃] for Am(III), where R₄N is the quaternary ammonium cation. The obtained data showed high efficiency of the studied carbonate system for extraction of U(VI) and its purification from Am(III). The maximum separation factor of U(VI) and Am(III) was 25.

KEYWORDS:

• Uranium(VI) carbonate and peroxo–carbonate complexes
• americium(III) carbonate complexes
• sodium carbonate
• hydrogen peroxide
• liquid–liquid extraction
• quaternary ammonium compounds
• methyltrioctylammonium carbonate
• toluene

Acknowledgments

The authors express deep gratitude to Alexander Chekmarev for his useful comments and guidance, both during the writing of this article and in everyday work, and convey sincere condolences on his untimely departure.

Supplementary material

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Additional information

Funding

The work was supported by Mendeleev University of Chemical Technology. Project № T008–2018.