Extraction of trivalent actinides

In an investigation of the extraction of trivalent actinides, An(III) from 0.01 M nitric acid solutions of various LiNOj concentrations into o-xylene containing the tertiary amine salt trilaurylmethylammonium nitrate, TLMA HNOj, Van Ooyen [29] found that the amine was monomeric only at very low concentrations (<0.1M in the organic phase) but at higher concentration formed both dimers and trimers. 

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. 

Yong-Jun, Z. Extraction of trivalent actinides with phosphine oxides, In Handbook on the Physics and Chemistry of Actinides, AJ. Freeman and C. Keller (Eds.), Elsevier Science, Amsterdam, North Holland (1985), p. 482. 

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 wide-rim CMPO calix[4]arenes are the most efficient compounds for the extraction of trivalent actinides and lanthanides. They are also the compounds that display the highest selectivity along the lanthanide series, provided that phosphorus atoms are linked to phenyl groups. They also display a higher selectivity than the calixarene-bearing diphosphine oxide, where the phosphorus atom is linked to phenyl units CPo21.176- ... 

Zhu, YJ. 1985. Extraction of trivalent actinides with phosphone oxides, in Handbook on the Physics and Chemistry of the Actinides Freeman, A.J., Keller, C. Eds. Elsevier Science Publishers B.V. Amsterdam, 469-511. 

Mathur, J. N. and Khopker, P. K. (1988) Use of crown ethers as synergists in the solvent extraction of trivalent actinides and lanthanides by l-phenyl-3-methyl-4-trifluoroacetyl-5-pyrazolone, Solvent Extr. IonExch, 6(1), 111-124. 

Table 16. Equilibrium constant data for the extraction of trivalent actinide ions by HTTA-B mixtures... 

The extraction of trivalent actinides with /3-diketones in the presence of crown ethers has also been investigated. Trifluoroacetylacetone(HTFA), HTTA, benzoyltrifluoroacetone(HBFy, and 2-napthoyltrifluoroacetone (HNFA) have all been used with 18-crown-6 to remove Am and Cm from perchlorate media into 1,2-dichloroethane. It has been shown that the mechanism of extraction for all of the /3-diketones (HA) is the formation of a cationic complex via a synergistic ion-pair extraction (SIPE) as shown in Equation (66) ... 

The preference of the SIPE for the trivalent actinides is due to the stabilization of the crown ether/ bonds due to a size-fitting effect where the diameter of the metal ion matches that of the crown ether cavity, leading to significantly greater extraction efficiency due to this synergistic effect. Another widely studied /3-diketone for the extraction of trivalent actinides has been l-phenyl-3-methyl-4-benzoylpyrazolone-5 (HPMBP), illustrated in Figure 93. The extraction of Am , Cm , Bk , and Cf by HPMBP may be expressed in two ways. First, the extraction of Cm has been observed to follow the extraction equilibrium shown in Equation (67) ... 

In the extraction of trivalent actinides, the dialkylphosphonic acids behave in a manner similar to that observed for the dialkylphosphoric acids. However, in some systems, they offer a greater intergroup separation between lanthanides and actinides. The separation of Cf and Cm from nitric acid solutions has been studied using 2-ethylhexylphenylphosphonic acid [HEH( P)] and 1-methyl-heptylphenylphosphonic acid [HMeH( P)]. ORNL has developed a process for intergroup actinide separation, called Hepex, based on the use of HEH( P) (72,73). ... 

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. 

The process consists of liquid-liquid solvent extraction of trivalent actinides and/or lanthanides from a dilute acid or salt solution in which the anion can be either nitrate or chloride. 

The TBP extraction process. The extraction of trivalent actinides by TBP may succeed, as well known, at low acidity conditions, provided a sufficient nitrate salt content is reached in the feed solution (13,14). However, the large amount of salting agents to be added to the HAW (tons of Na and Al nitrate per ton of spent... 

The Double-Double Effect in Complex Formation and Extraction of Trivalent Actinides. 35... 

Complexation and extraction of trivalent actinides and lanthanides by triazinylpyridine N-donor ligands 13CRV1199. 

They reported the distribution ratios (Dm) of lanthanide and actinide ions and compared the Dm values with that of Am " in the extraction system of 1 M HNO3 and 0.1 M TODGA/ M-dodecane as shown in Table 18.11. The order of extractability of actinide ions from 1 M HNO3 is An, An > An02 > An02. The TODGA has an ability of co-extraction of trivalent actinide ions and lanthanide ions from high-level liquid radioactive waste. 

The prospective systems were recently reviewed and summarized by Alyapyshev et al. (2008). These, as noted above, might be considered as conceptual technological systems for the extraction of trivalent actinides withont extracting weight amounts of lanthanides, UNEX B processes. No snch process was as yet apparently tried in the countercurrent line. 

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. 

Panak PJ, Geist A. Complexation and Extraction of Trivalent Actinides and Lanthanides by Triazinylpyridine N-Donor Ligands. Chem Rev. 2013 113 1199—1236. 

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