Nuclear wastes, actinides/lanthanides

Nilsson, M., Ekberg, C., Foreman, M. et al. 2006. Separation of actinides(III) from lanthanides(III) in simulated nuclear waste streams using 6,6 -bis-(5,6-dipentyl-[l,2,4] triazin-3-yl)-[2,2 ]bipyridinyl (C5-BTBP) in cyclohexanone. Solvent Extr. Ion Exch. 

Danesi, P.R. Chiarizia, R. Rickert, P. Horwitz, E.P. Separation of actinides and lanthanides from acidic nuclear wastes by supported liquid membranes, Solvent Extr. Ion Exch. 3 (1985) 111-147. 

Shaibu, B.S. Reddy, M.L.P. Bhattacharyya, A. Manchanda, V.K. Evaluation of Cyanex 923-coated magnetic particles for the extraction and separation of lanthanides and actinides from nuclear waste streams, J. Magn. Magn. Mater. 301 (2006) 312-318. 

Shaibu, B. S Reddy, M. L. P Murali, M. S and Manchanda, V. K N,N,N ,N -tetraoctyl-3-oxapentane-l,5-diamide impregnated magnetic particles for the uptake of lanthanides and actinides from nuclear waste streams, Radiochim. Acta, 95, 159-164, 2007. 

Complexes of the lanthanides with the rather similar terdentate hgands 2,2 6, 2"-terpyridyl (terpy), 2,4,6-tris-2-pyridyl-l,3,5-triazine (tptz), 4-amino-bis(2,6-(2-pyridyl))-1,3,5-triazine (abptz), and related ligands have been studied iu cousiderable detail aud uumber, as these terdentate N-donor ligands are efficient in separating actinides from lanthanides selectively by solvent extraction, of obvious relevance to processing nuclear waste. 

Chitry, F. et al., Lanthanides(ttt)/actinides(III) separation by nano-filtration-complexation in aqueous medium, in Proceedings of International Conference, Nuclear waste From Research to Industrial Maturity, Montpellier, Oct. 2-4, 2000. 

Supported liquid membranes, consisting of an organic solution of -octyl(phenyl)-A,iV-diisobutylcarbamoylmethylpho-sphine oxide (CMPO) and tributyl-phosphate (TBP) in decalin, were capable of selective separation and concentration of actinide and lanthanide ions from aqueous nitrate feed solutions and from synthetic nuclear wastes where the strip solution is a mixture of formic acid (FA) and hydroxylammonium formate (HAF) [106,107]. TBP is added to CMPO to improve its solubility in aliphatic diluents. Although low concentration of nitric acid was initially used as the strippant solution, a gradual... 

Chiarizia, R., Danesi, P. R. (1987). A double liquid membrane for the removal of actinides and lanthanides from acidic nuclear wastes. Separation Science and Technology 22 641-649. 

Boatner LA, Beall GW, Abraham MM, Finch CB, Huray PG, Rappaz M (1980) Monazite and other lanthanide orthophosphates as alternate actinide waste forms. In Scientific Basis for Nuclear Waste Management, vol. 2, Northrap, CJM Jr (ed) Plenum Press, New York, p 289-296 Brandel V, Dacheux N, Genet M (1996) Reexamination of uranium (IV) phosphate chemistry. J Solid State Chem 121 467-472... 

Several bifunctional organophosphorus ligands have been found to be efficient liquid-liquid extractants for lanthanide and actinide ions present in highly acidic aqueous nuclear waste solutions. The (carbamoylmethyl)phosphonates, (RO)2P(0) CHzCCOlNRj, and in particular dihexyl [(iV,iV-diethylcarbamoyl)methyl] phos-phonate (DHDECMP) have attracted the most attention because of the low aqueous-phase solubilities and superior radiolytic stabilities of the ligands. 

Ansari, S.A., Mohapatra, P.K., Raut, D.R., Seshagiri, T.K., Rajeswari, B., and Manchanda, V.K. 2009. Performance of actinide partitioning extractants in hollow fiber supported liquid membrane for the transport of actinides and lanthanides from high level nuclear waste. J. Membr. Sci. 337 304-309. 

The redox reaction has been utilized in the separation of light actinide elements (U, Np, and Pu) with both ion-exchange process and solvent extraction process. For trivalent heavy actinides with Z> 94 (except No), separation of these actinide ions from lanthanide ions is required for safe storage of long-lived nuclear waste and transmutation of these nuclides. Fundamental researches have widely been carried out by several groups for the purpose of quantitative separation of transuranium elements. Recent topics on the development and application of solvent extraction for the separation of transuranium elements are briefly summarized below. 

These oxygen-donor type extractants have potential for co-extraction of trivalent lanthanide and actinide ions. For the mutual separation between trivalent actinides and lanthanides, so-called soft-donor (nitrogen-donor type and sulfur-donor type) extractants are promising and widely investigated for the application of nuclear waste treatment as follows. 

The impregnation of these peculiar aerogels is proposed to trap the nuclear wastes in a silica matrix. After a soaking treatment, the host matrix is dried, then sintered. The expected material is a nanocomposite constituted by nuclear wastes crystals embedded into a silica matrix. For safety reasons the lanthanides, Ce and Nd, are used to simulate the III and IV valent actinides [26-28] [for example, Am(III), Cm(III), Np(IV), Pu(IV)]. Nd and Ce as actinides surrogates have been also chosen because of their dissimilar affinity to silica. Hence, Nd and Ce will lead to different kinds of glass-ceramics, simulating the possible behaviors of the actinides in the presence of silica depending on their silica affinity. 

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