title: Supercritical fluid extraction and separation of uranium from other actinides.
abstract: The feasibility of separating U from nitric acid solutions of mixed actinides using tri-n-butylphosphate (TBP)-modified supercritical fluid carbon dioxide (sc-CO2) was investigated. The actinides U, Np, Pu, and Am were extracted into sc-CO2 modified with TBP from a range of nitric acid concentrations, in the absence of, or in the presence of, a number of traditional reducing and/or complexing agents to demonstrate the separation of these metals from U under sc-CO2 conditions. The separation of U from Pu using sc-CO2 was successful at nitric acid concentrations of less than 3M in the presence of acetohydroxamic acid (AHA) or oxalic acid (OA) to mitigate Pu extraction, and the separation of U from Np was successful at nitric acid concentrations of less than 1M in the presence of AHA, OA, or sodium nitrite to mitigate Np extraction. Americium was not well extracted under any condition studied.
authors.affiliation: Department of Chemistry, University of Idaho, Moscow, ID 83844, USA.
authors.forename: Donna L
authors.initials: DL
authors.lastname: Quach
authors.affiliation: Idaho National Laboratory, Idaho Falls, ID 83415, USA. Electronic address: bruce.mincher@inl.gov.
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Mincher
authors.affiliation: Department of Chemistry, University of Idaho, Moscow, ID 83844, USA.
authors.forename: Chien M
authors.initials: CM
authors.lastname: Wai
mesh_terms: D008671:Actinoid Series Elements / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry; D025924:Chromatography, Supercritical Fluid; D017942:Nitric Acid / Q000737:chemistry; D059027:Recycling / Q000379:methods*; D018505:Waste Management / Q000379:methods*
chemical_list: D008671:Actinoid Series Elements; D002245:Carbon Dioxide; D017942:Nitric Acid
keywords: Actinide separations; High level waste; Nuclear fuel cycle; Supercritical fluid extraction