Extractants of transplutonium elements

Zilberman, B.Y., Fedorov, Y.S., Shmidt, O.V., Goletskiy, N.D., Shiskin, D.N., Esymantovskiy, V.M., Rodionov, S.A., Egorova, O.N., Palenik, Y.V. 2007. Usage of dibutyl phosphoric acid and its zirconium salt for extraction of transplutonium elements and rare earths with their partitioning. Global 2007 Advanced Nuclear Fuel Cycles and Systems, September, Boise, ID. 

Solvent Extraction of Transplutonium Elements from Acid Solutions by Polydentate Neutral Organophosphorus Compounds and from Alkaline Solutions by Quarternary Ammonium Bases and by Alkylpyrocatechols... 

Extraction of transplutonium elements from acid solution... 

Baybarz, R. D. (1965). Dissociation contents of the transplutonium chelates with diethylenetriaminepentaacetic acid (DTPA) and the application of DTPA chelates to solvent extraction separations of transplutonium elements from the lanthanide elements, J. Inorg. Nucl. Chem. 27,1831. 

Schulz, W. W. Navratil, J. D. Solvent extraction with neutral bidentate organic phosphorus reagents. In Recent Developments in Separation Science, Li, N. N. Ed. CRC Press Boca Raton, Florida, 1982 Vol. VII, pp. 31-72. Myaesoedov, B. F. Chmutova, M. K. New methods of transplutonium elements isolation, purification and separation. In Separation of f Elements, Nash, K. L. Choppin, G. R. Eds. Plenum Press New York, 1995 p. 11. 

Treatment of irradiated targets. The chemical operations relative to the production of transplutonium elements (americium 243, curium 244) are all performed using a nitric acid medium. The highly corrosive nature of the solutions concentrated with Cl" ions, which were used in the USA for the development of the Tramex process (JO, and the instability of SCN" ions to radiation (12), led us to select nitric acid solution to perform the chemical separations. Once the medium was selected, it was necessary to find an adequate additive which, in combination with a suitable extractant, would allow solution of the main problem namely separation of the trivalent actinides from triva-lent lanthanides. 

The development of the program for the production of transplutonium elements, americium 241, americium 243 and curium 244 in France required a major effort from the technological and chemical standpoints. Pre-existing hot cells were reconditioned and others were specially built for these production operations. From the chemical standpoint, the development of extractive chromatography on the preparative scale has allowed the definition of simple processes whose performance characteristics in our operating conditions have proved to be better than those obtained by liquid-liquid extraction. This type of process, initially developed for the treatment of Pu/Al targets, is ideal for the treatment of industrial wastes for their decontamination and for the production of americium 241. 

Extraction processes (TRUEX, PUREX, Talspeak, DIAMEX, PARC, etc.) generally involve complexation of transplutonium elements by alkyl phosphines, phosphine oxides, phosphoric acids, carbamoyl phosphonates, diamides, and thiophosphinates in aqueous/organic extractions, within derivatized solid supports, or on coated particles. There are excellent reviews of the processes and significant complexes by Mathur et al. and selected chapters in The Chemistry of the Actinide and Transactinide Elements to be published in 2003. " Work on the separation for nuclear waste management in the United States, France, and Russia have been reviewed. " ... 

The separation of transplutonium elements from the lanthanides constitutes the delicate phase of chemical treatment, owing to their comparable affinities for the usual extractants HDEHP, TBP and TLAHNO3. Among all the systems described in the literature and covered by a recently published critical compilation (JO), we selected those which appeared to be much suitable for adaptation to extraction chromatography the Talspeak process (7) and the... 

Zilberman, B. Y, Fedorov, Y. S., Shmidt, O. V. et al. 2009. Dibutyl phosphoric acid and its acid zirconium salt as an extractant for the separation of transplutonium elements and rare earths and for their partitioning. J. Radioanal. Nucl. Chem. 279 193-208. 

Extraction by means of tertiary amines is very important technologically. Most of the uranium presently produced is separated by such a process, working with a mixture of long-chain tertiary amines [166]. Also, extraction by tertiary amines is generally applied for the separation of transplutonium elements on a large scale... 

Solvent extraction of long-lived transplutonium elements, particularly Am and Cm, from HLLW, is primarily based on two classes of compounds ... 

Tachimori, S., Sato, A., Nakamura, H. 1979. Separation of transplutonium and rare-earth elements by extraction with di-A< -decyl phosphoric acid from DTPA solution. J. Nucl. Sci. Technol. 16 434 140. 

Shmidt, O.V., Zilberman, B.Ya., Fedorov, Yu.S., Suglobov, D.N., Puzikov, V.A., Mashkov, L.G., Palenik, Yu.V., Glekov, R.G. Extraction properties of dibutylphosphoric acid zirconium salt in recovery of transplutonium and rare-earth elements from nitric acid solution. Radiokhimiya (2002), 44 (5), 428 133. 

Phosphine oxides. Few molecular complexes of trivalent transplutonium elements have been reported. Several studies examine the extraction chemistry of Am, Cm, and Bk with a combination of /3-diketones and tri-n-alkyl phosphine oxides and tiialkylphosphates. From these, compounds reported to be of the formula AnF3(R3PO) c (An = Am, Cm R = n-octyl, Bu"0) were isolated, where L = CF3COCHCOR (R = Me, CF3, Bu ). The stoichiometry of the complexes (An P=0) was not always reported. The complex Am(CF3COCHCOCF3)3[OP(OBu )3]2 is reported to be volatile at 175 °C. ... 

This involves the use of tertiary amine extraction of the An ions from acidic 11 M LiCl solutions. Spectroscopic studies have indicated that, in the cases of Am and Nd at least, the octahedral trianionic hexachloro complexes are extracted from 11 M LiCl. Stability constant data for the chloride complexing of Am , and Cfin media of ionic strength 1,0 have been reported. Tertiary amines also extract Pu and a study of extraction from nitrate media by trilaurylamine (TLA) in xylene has been reported. " This showed that the mass transfer rate was controlled by the reactions between Pu from the bulk phase and interfacially adsorbed TLA-HNOs. The separation of individual transplutonium elements from the Tramex actinide product may be achieved using ion exchange or precipitation techniques." ... 

In certain applications, the quaternary ammonium salts have advantages over tertiary amines for actinide extractions. Quantitative extraction of the transplutonium elements from nitrate media by quaternary ammonium salts can be achieved with a lower aqueous-phase nitrate concentration than is required for tertiary amines thus, aluminum nitrate may be used instead of lithium nitrate. The separation factor between Am and Cm can be as high as three in a quaternary ammonium nitrate system (50). The effect of the length of the alkyl chain on Cm, Am, Bk, Cf, and Es extraction by alkyldioctylammonium nitrates suggests that steric factors substantially influence the extraction selectivity (51). A comparison of the extraction of tetravalent and hexavalent actinides by tetraheptyl ammonium nitrate shows that tetravalent ions are more easily extracted than hexavalent ions e.g.,... 

The acid dependency observed in practice hal been only approximately inverse third power. Impurities in Cleanex feed solutions often cause a departure from ideality (e.g., by common-ion effect or by consumption of some of the HDEHP), and we have not been able to control the extraction of the actinide elements solely by monitoring the aqueous-phase acidity. Fortunately, when processing transplutonium elements, the high specific activity of 21+I+Cm facilitates the detection of that isotope in both phases, thus permitting a rapid determination of the degree of extraction. The extraction coefficients of the trivalent actinides and lanthanides are all quite similar, so the 21+1+Cm serves as an excellent marker for all the extracted ions. 

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