Lanthanides separating

RE(N0 )2 NH NO 4H20 for light lanthanide separation (La, Nd, Pr) 2RE(N02)3 3Mg(N03)2 24H20 for middle lanthanide separation (Sm, Eu, Gd). Bromates and ethylsulfates have been found useful. Fractional crystallization is particularly slow and tedious for the medium and heavy rare earths. 

Extraction by carboxyUc acids (qv) is carried out in a neutral or weaMy acidic medium. The most widely used carboxyUc acid is RR (CH2)CCOOH, where Rplus represents seven carbon atoms. Trade names are Versatic 10 (Shell Chemicals) and Neodecanoic acid (Exxon Chemicals). CarboxyUc acids can be used either in chloride or in nitrate media and have a better selectivity for light lanthanides than for heavy lanthanide separation. 

What became known as the tetrad effect was first observed in the late 1960s during lanthanide separation experiments [25]. Fig. 1.3 shows a plot of log K, where is the distribution ratio between the aqueous and organic phases in a liquid-liquid extraction system. There are four humps separated by three minima, first at the f /f pair, secondly at the f point, and thirdly at the pair. 

Mainly inorganic, especially mixtures of metals with similar chemical characteristics, e.g. lanthanides separation of amino acids. 

Another area where titration calorimetry has found intensive application, and where the importance of heat flow versus isoperibol calorimetry has been growing, is the energetics of metal-ligand complexation. Morss, Nash, and Ensor [225], for example, used potenciometric titrations and heat flow isothermal titration calorimetry to study the complexation of UO "1" and trivalent lanthanide cations by tetrahydrofuran-2,3,4,5-tetracarboxylic acid (THFTCA), in aqueous solution. Their general goal was to investigate the potential application of THFTCA for actinide and lanthanide separation, and nuclear fuels processing. The obtained results (table 11.1) indicated that the 1 1 complexes formed in the reaction (M = La, Nd, Eu, Dy, andTm)... 

The many laboratories involved in this work allowed a large experimental program to be set up to test the behavior of these soft donor extractants in countercurrent separations. The trivalent actinide-lanthanide separation process was named SANEX and four chemical systems have been explored (Fig. 12.20) ... 

Kolarik, Z. Miillich, U. Gassner, F. Solv. Ext. Ion Exch., 1999, 17, 23, 1155. Musikas, C. Proceedings of the International Symposium on ActinidesjLanthanides Separations Honolulu, Hawaii, 1984 and Actinide-Lanthanide Separation World Scientific Singapore, 1985 p. 19. 

Nuclear Energy Research Initiative (NERI) Final Report. 2005. Advanced extraction methods for actinide/lanthanide separations. Submitted by University of Florida, PI Scott, M.J., collaborating organization Argonne National Laboratory. PNNL-13221. 

Since the 1960s, considerable efforts have been devoted worldwide to develop viable An(III)/Ln(III) separation systems, either by liquid-liquid extraction, precipitation, or ion-exchange chromatography. These systems have been regularly reported in comprehensive reviews covering various issues of actinide and lanthanide separations, such as the basics of actinide solution chemistry in aqueous/... 

Choppin, G.R. 1985. Separation of actinides in aqueous solution by oxidation state. In Actinide/Lanthanide Separations, eds. G.R. Choppin, J.D. Navratil, W.W. Schulz. Singapore World Scientific. 

Dam, H.H., Reinhoudt, D.N., Verboom, W. 2007. Multicoordinate ligands for actinide/ lanthanide separations. Chemical Society Review 36 361-ill. 

Under the same conditions, in contrast to what is observed for calix[4]arene-bearing CMPO moieties, with CPil2, distribution ratios of lanthanides increase from the lightest lanthanide, lanthanum, to europium. Americium can be easily separated from the lightest lanthanides (separation factor DAm/La > 20, DAm/Ce =15, /lAlll,Nd = 10, UAi /si = 7.5, DAm/Eu = 6), which are the most abundant lanthanides in fission-product solution. Cavitands bearing picolinamide (Cv5) or thiopicolin-amide (Cv6) residues seems much less selective than their calixarene counterparts, giving SAm/Eu < 2.18... 

G. R. Choppin, J. D. Navratil, W. W. Schulz (Eds.), Actinides-Lanthanides Separation, World Scientific, Singapore, 1985... 

Continual progress in rare-earth processing has reduced the radioactive impurities in rare-earth products substantially, so they are practically free of radioactivity today. Current processing technology for mineral recovery and for the subsequent lanthanide separation results in products that meet all regulatory requirements. 

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