Lanthanide trivalent actinides from

Jarvinen, G., Barrans, R., Schroeder, N. et al. 1994. Selective extraction of trivalent actinides from lanthanides with dithiophosphinic acids and tributylphosphate. American Chemical Society, San Diego, CA, March. LA-lJR-94-4350. 

Modolo, G., Odoj, R. 1998. Influence of the purity and irradiation stability of Cyanex 301 on the separation of trivalent actinides from lanthanides by solvent extraction. J. Radioanal. Nucl. Chem. 228 (1-2) 83-89. 

Cordier, P.Y., Francois, N., Boubals, N., Madic, C., Hudson, M.J., Liljenzin, J.O. 1999. Synergistic systems for the selective extraction of trivalent actinides from mixtures of trivalent actinides and lanthanides. ISEC 99 Conference on Solvent Extraction for the 21st Century, July, Barcelona, Spain. 

The grafting of CMPO moieties on the narrow rim affords a strong decrease of extracting ability toward lanthanides, trivalent actinides, and tetravalent plutonium from acidic solutions. The distribution ratios for the different calixarenes in NPHE are low, except for CPn3 for which the number of carbon atoms in the spacer is four, but even for this compound, the distribution ratios are lower than those obtained with their wide-rim counterparts (Figure 4.11). 

To minimize corrosion of stainless steel equipment all the processes use nitric acid solutions. Hence polyaminoacetic acid complexing agents such as DTPA are required to accomplish the critical problem of the separation of trivalent actinides from trivalent lanthanides 2). 

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. 

Marcus, Y. Anion exchange of metal complexes. XV. Anion exchange and amine extraction of lanthanides and trivalent actinides from chloride solutions, J. Inorg. Nucl. Chem., 28, 209 (1966). 

Amines can also be used to separate the trivalent actinides from the chemically similar trivalent lanthanides. In the Tramex process, a tertiary amine is used as the extractant from 10 to 12 M LiCl, 0.1 to 0.3 N A1C13, and 0.01 M HC1 (13,JA). The development... 

Our studies have shown that in the presence of complex-forming agents actinides and lanthanides can be extracted from alkaline solution by using of ali-quat 336 and 4( c , oC -dioctylethyl)pyrocatechol. The latter reagent is more efficient, as it provides for quantitative extraction of trivalent actinides from very alkaline media and for appreciably better separation of actinides from rare earth elements. 

Cyanex-301 (bis(2,4,4-trimethyl pentyl) dithiophosphinic acid) has been extensively studied for lanthanide-actinide separation, either alone or in the presence of synergists [62,63], Solvent extraction studies using Cyanex-301 had indicated the following two-phase extraction equilibria for the extraction of trivalent lanthanides and actinides from aqueous nitrate medium [63] ... 

Bhattacharyya, A., Mohapatra, P.K., Ansari, S.A., Raut, D.R., and Manchanda, V.K. 2008. Separation of trivalent actinides from lanthanides using hollow fiber supported liquid membrane containing Cyanex-301 as carrier. J. Membr. Sci. 312 1-5. 

BTP, BTBP system. Kolarik et al. (1999, 2008) and Madic et al. (2000) carried out comprehensive study of the separation of trivalent actinides from lanthanides by the nitrogen donor extractants. They developed several new nitrogen polydentate ligands, BTP [2,6-bis(5,6-dialkyl-l,2,4-triazin-3-yl)-4-alkyl-pyridines] and BTBP [6,6 -bis-(5,6-diethyl-[l,2,4]triazin-3-yl)-2,2 -bipyridyl] see O Fig. 18.22). 

Cyanex-301 system. The sulfur type soft-donor extractant, thiophosphoric acid has potential for selective separation of trivalent actinides from lanthanides (Musikas 1985). Zhu et al. (Zhu 1995 Zhu et al. 1996) developed dithiophosphinic acid type extractant, Cyanex-301... 

Efficient separation of trivalent actinides from lanthanides is possible. 

In these extractants, HNO3 interaction with the extractant occurs with the carbamoyl portion of the molecule (Horwitz etal. 1981), leaving the solvating phosphorus portion of the molecule to interact with the metal ion. These compounds are indeed more efficient extractants of the trivalent metal ions from acidic solutions, able to extract trivalent actinide and lanthanide ions from relatively dilute nitric-acid solutions. Horwitz et al. (1981) have studied the separation of the lanthanides and trivalent actinides from Am to Fm (table 2) using dihexyl-N, N-diethylcarbamoyl-methylphosphonate (DHDECMP) and aqueous nitrate solutions. Steadily decreasing distribution ratios are observed for the lanthanides, but nearly constant D s are found for the trivalent actinides. Group separation does not appear feasible while interlanthanide (but probably not interactinide) separations are possible. However, substitu-... 

Separation factors for TTA extraction of trivalent lanthanides and actinides from Stary (1966) (TTA/toluene) and Alstad etal. (1974) (TTA/Caj. 

Separation factors (relative to Cm) for ammonium a-hydroxyisobutyrate cation exchange of trivalent lanthanides and actinides from Smith and Hoffman (1956), Choppin et al. (1956), and Choppin and Silva... 

Publications on the analysis of soil samples by Smith et al. [78] and Crain et al. [79] summarized two possible routes for the analysis of aqueous samples in chromatography extraction columns, with detection by conventional radiometric techniques such as ICP-MS. In this procedure, TRU-Spec SPS columns were used for group separation of actinides and TEVA-Spec columns were used to isolate the trivalent actinides from the lanthanide elements. A reduced solution (with ascorbic acid) was passed through a 1 mL TRU-Spec column equilibrated with 2 M nitric acid and 0.5 M aluminum nitrate. The trivalent actinides including americium and the lanthanide elements were eluted from the column with 12 mL of 4 M HCl. Plutonium and thorium were removed with 30 mL of... 

As demonstrated, this family of extractants allows for a good extraction of trivalent lanthanides and actinides from most fission products present in the simulated PUREX feed. Most compounds... 

Before its discovery, the trivalent state was predicted to be the most stable in aqueous solution and, therefore, Md was expected to exhibit a chemical behavior similar to the other 3 + actinides and lanthanides [43]. The elution of Md just prior to Fm in the elution sequence of trivalent actinides from a cation-exchange column observed in the discovery experiments appeared to confirm this prediction. Mendelevium forms insoluble hydroxides and fluorides that are... 

G. Jarvinen et al "Selective Extraction of Trivalent Actinides from Lanthanides with Dithiophosphinic Acids and Tributylphosphate." in Separations off Elements, 1994, K. L. Nash G. R. Choppin Ed. Plenum Press, New York pp 43-62. 

In contrast to the situation observed in the trivalent lanthanide and actinide sulfates, the enthalpies and entropies of complexation for the 1 1 complexes are not constant across this series of tetravalent actinide sulfates. In order to compare these results, the thermodynamic parameters for the reaction between the tetravalent actinide ions and HSOIJ were corrected for the ionization of HSOi as was done above in the discussion of the trivalent complexes. The corrected results are tabulated in Table V. The enthalpies are found to vary from +9.8 to+41.7 kj/m and the entropies from +101 to +213 J/m°K. Both the enthalpy and entropy increase from ll1 "1" to Pu1 with the ThSOfj parameters being similar to those of NpS0 +. Complex stability is derived from a very favorable entropy contribution implying (not surprisingly) that these complexes are inner sphere in nature. 

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