Reprocessing of spent nuclear fuel usually employs the solvent extraction technique to recover fissile material, isolate other valuable radionuclides, recover precious metals, and remove contaminants. Efficient recovery of these species from highly radioactive solutions requires a detailed understanding of reaction conditions and metal speciation that leads to their isolation in pure forms. Due to the complex nature of these systems, identification of ideal reaction conditions for the efficient extraction of specific metals can be challenging. Thus, the development of experimental approaches that have the potential to reduce the number of experiments required to identify ideal conditions are desirable. In this study, a full-factorial experimental design was used to identify the main effects and variable interactions of three chemical parameters on the extraction of protactinium (Pa). Specifically we investigated the main effects of the anion concentration (NO3-, Cl-) extractant concentration, and solution acidity on the overall extraction of protactinium by 2,6-dimethyl-4-heptanol (diisobutylcarbinol; DIBC) from both HCl and HNO3 solutions. Our results indicate that in HCl, the extraction of protactinium was dominated by the solution acidity, while in nitric acid the extraction was strongly effected by the [DIBC]. Based on our results, a mathematical model was derived, that describes the relationship between concentrations of anions, extractant, and solution acidity and the expected values of Pa distribution coefficients in both HCl and HNO3. This study demonstrates the potential to predict the distribution coefficient values, based upon a mathematical model generated by a full-factorial experimental design.
Department of Chemistry, E373 CB, The University of Iowa, Iowa City, IA 52246, USA and Interdisciplinary Human Toxicology Program, E373 CB, The University of Iowa, IA 52246, USA and Departments of Radiology and Radiation Oncology (Free Radical and Radiation Biology Program), The University of Iowa, ML B180 FRRB, 500 Newton Road, Iowa City, IA 52246, USA, Tel.: +1 319 335-8017
1. King, J.C. (1987). The impact of separation science and technology on some key technological challenges facing society. In R. Price (Ed.), Separation and purification: Critical needs and opportunities. Washington, D. C., USA: National Academy Press.
2. Nuclear Energy Agency with Working Party on Nuclear Criticality Safety and Expert Group on Assay Data of Spent Nuclar Fuel. (2011). Spent nuclear fuel assay data for isotopic validation. Organisation for Economic Co-operation and Development. NEA.
3. International Atomic Energy Agency. (2007). Use of reprocessed uranium. In Technical Committee Meeting. Vienna, Austria: IAEA. (IAEA-TECDOC-CD-1630).
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