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Uranium Dioxide in Ionic Liquid with a Tri-n-butylphosphate-HNO3 Complex - Dissolution and Coordination Environment

Journal Article · · Dalton Transactions
DOI:https://doi.org/10.1039/C0DT01518K· OSTI ID:1845876

Uranium dioxide can be dissolved directly in an imidiazolium-based ionic liquid (IL) at room temperature with a tri-n-butylphosphate(TBP)-HNO3 complex. The dissolution process follows pseudo first-order kinetics initially. Raman spectroscopic studies show the dissolved uranyl ions are coordinated with TBP in the IL phase with a molar ratio of (UO2)2+: TBP = 1:2. The dissolved uranyl species can be effectively transferred to supercritical fluid carbon dioxide (sc-CO2) phase. No aqueous phase is formed in either the IL dissolution or the supercritical fluid extraction process. Absorption spectra of the extracted uranyl species in the sc-CO2 phase suggests the presence of an UO2(TBP)2(NO3)2 and HNO3 adduct probably of the form UO2(TBP)2(NO3)2·HNO3. The adduct dissociates in a water-dodecane trap solution during pressure reduction resulting in UO2(TBP)2(NO3)2 collected in the dodecane phase.

Research Organization:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
AC05-76RL01830
OSTI ID:
1845876
Report Number(s):
PNNL-SA-78548
Journal Information:
Dalton Transactions, Journal Name: Dalton Transactions Journal Issue: 18 Vol. 40
Country of Publication:
United States
Language:
English

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