Analytical Sciences

Abstract − Analytical Sciences, 22(11), 1387 (2006).

Selective Extraction of Uranium from a Mixture of Metal or Metal Oxides by a Tri-n-butylphosphate Complex with HNO3 and H2O in Supercritical CO2
Takashi SHIMADA,*,*** Sinya OGUMO,*** Kayo SAWADA,* Youichi ENOKIDA,* and Ichiro YAMAMOTO**
*EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603, Japan
**Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603, Japan
***Nuclear Energy Systems Engineering Center, Mitsubishi Heavy Industries, Ltd., 16-5 Konan 2-chome, Minato, Tokyo 108-8251, Japan
In order to study the decontamination nature of the reactive extraction of uranium in the presence of some metal chemicals using a single-phase mixture of HNO3, H2O and tri-n-butylphosphate (TBP) in supercritical carbon dioxide (SC-CO2), we measured the decontamination factors (DFs) of Sr, Zr, Mo, Ru, Pd, Ce and Nd from their mixture with U. These elements were originally added to U3O8 as SrO, ZrO2, MoO3, RuO2, Pd, CeO2 and Nd2O3, and the extraction was performed at 18 MPa and 323 K with the single-phase mixture. The DFs for these elements were determined to be greater than 103 when the molecular ratio of U to TBP in the extracted complex was greater than 0.3. Dilution by SC-CO2 effectively increased the DFs.