Recovery of uranium from various matrices is crucial in the energy and nuclear industries. In the recovery process an extractant is required to cause the uranium to a stage which is capable of being extracted by the extraction solvent. In this work, supercritical carbon dioxide fluid extraction using N,N,N',N'-tetrabutyl-3-oxapentanediamide�HNO3 (TBODA-HNO3) as an extractant has been proposed to successfully achieve this aim. U(IV) in the UO2 containing solid is directly oxidized to U(VI) in the form of UO22+ in supercritical carbon dioxide (sc-CO2) containing a CO2-soluble TBODA-HNO3 extractant at 200 atm and 50 oC. The TBODA-HNO3 extractant has a chemical composition of TBODA(HNO3)1.0(H2O)1.5. The resulting UO22+/TBODA complex can be consequently extracted with acetone-modified sc-CO2 under the same conditions as employed with the neat sc-CO2. The chemical composition of the UO22+/TBODA complex is proposed to be in the form of an ion pair, [UO2(TBODA)2]2+-2(NO3-).

Characteristics of oxa-diamide-HNO<sub>3</sub> extractant in the supercritical fluid extraction of uranium from solid phase

246th National Meeting (2013)

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Characteristics of oxa-diamide-HNO3 extractant in the supercritical fluid extraction of uranium from solid phase

Characteristics of oxa-diamide-HNO₃ extractant in the supercritical fluid extraction of uranium from solid phase