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The history of the development of fluorinated compounds as potential diluents in solvent extraction processes is described. Fluorinated diluents were first investigated in the former Soviet Union and later in the United States and Europe. Fluorinated diluents represent a class of compounds that can be used as primary diluents or as phase modifiers. They are of particular utility when extractant solubility is limited in traditional hydrocarbon diluents and a polar diluent is needed. The chemical and physical characterisitics of fluorinated diluents are provided for a broad range of compounds. Other properties such as toxidcity and resistance to radiolysis are described. Fluorinated compounds have been studied for over 40 years and have been used at industrial scale as a primary diluent for cesium and strontium extraction in Russia and as a phase modifer for an insustrial-scale cesium extraction process in the United States. The advantages and disadvantages of traditional hydrocarbon diluents are compared with chlorinated diluents, chlorinated and fluorinated diluents, and a number of different types of fluorinated diluents. Developing trends for teh use of fluorinated diluents in solvent extraction processes are discussed. This article should provide assistance to researchers investigating new or improved solvent extraction processes where traditional hydrocarbon diluents may not be appropriate. [ABSTRACT FROM AUTHOR]

New non-inflammable compounds – carbonates of fluorinated alcohols were proposed as potential diluents for tributyl phosphate (TBP). These compounds are commercially available, have high boiling point, high density, and low solubility in water solutions. Extraction of actinides from nitric acid by TBP solutions in fluorinated carbonates was studied. TBP solutions in fluorinated carbonates show lower extraction ability comparing with TBP solutions in hydrocarbon diluents. In spite of this, it is possible to extract more than 99.9% of tetra- and hexavalent actinides presented in spent nuclear fuel solutions. The advantage of proposed solvent is possibility to obtain uranium strip product with uranium concentration higher than 100 g/l. [ABSTRACT FROM AUTHOR]

The extraction of americium and lanthanides by diamides of 2,2′-dipyridyl-6,6′-dicarboxilic acid solutions in polar diluents was investigated. The dependence of extraction properties of the diamides on their structure was studied and the distribution ratios of americium and lanthanides from nitric acid solutions were determined. The highest extraction was found for the compounds with the ethyl-group and the alkyl-substituted aryl-group on the amidic nitrogen. The Am/Ln separation factors higher than 10 were achieved for extraction from high acidity media. [ABSTRACT FROM AUTHOR]

New ethyltolyl-substituted derivatives of dipicolinic acid,N,N-diethyl-N',N'-ditolyl diamides (DPA) have been synthesized and evaluated for their extraction capability toward americium and lanthanides. These diamides were studied as a stand-alone extractant in conjunction with a polar solvent FS-13 (trifluoromethylphenyl sulfone) as well as in an extraction mixture in conjunction with the synergistic extractant chlorinated cobalt dicarbollide and FS-13. The effect of the ortho-, meta-, and para position of the methyl group on the tolyl ring of theN,N'-diethyl-N,N'-ditolyl-diamide (EtTDPA) was investigated. Data on the extraction ability of different diamides of dipicolinic acid show that the Et(o)TDPA has the most promising properties because it has the best balanced selectivity between the heavy and light lanthanoids. [ABSTRACT FROM AUTHOR]

New diamides of dipicolinic acid have been prepared and their affinity for lanthanides, americium, and uranium has been explored using the liquid-liquid extraction method. These extractants feature mixed alkyl/aryl substituents. The highest extraction is seen for phenyl/ethyl derivatives. The structure-reactivity relationship for extraction and solubility is discussed. [ABSTRACT FROM AUTHOR]

Extraction of Am and Eu using mixtures of diphosphinc dioxides (DPDO, e.g., (R1)2P(O)(CH2)nP(O)(R2)2 where R1, R2 = Ph, Bu; n = 1,2), with and without chlorinated cobalt dicarbollide (CCD) in the polar diluents 1,2-dichloroethane (DCE)+ meta-nitrobenzotrifluoride (F-3), bis-tetrafluoropropyl ether of diethylene glycol (F-8) and phenyltrifluoromethyl sulfone (FS-13) from HNO3, HClO4, LiNO3 and LiClO4 solutions has been investigated. The anomalous aryl strengthening (AAS) effect, i.e. the anomalous increase of extraction ability of methylene bridged diphosphine dioxides due to substitution of aromatic (i.e., phenyl) for alkyl (e.g., butyl or octyl) moieties (DAm increases by three to lour orders of magnitude), is only observed during the extraction of Am and Eu from acidic media. In salt media the AAS effect is weakly observed, and is practically absent in such diluents as F-3 and FS-13. The extraction isotherm in the case of DPDO with an observed AAS effect indicates the distribution coefficients of Eu decrease by a factor of two to three, even at the concentration ratio of DPDO:Eu = 50:1; however, these values decrease only by L0% for the DPDO that do not indicate an observed AAS effect. It is proposed that the presence of water in the diluent is necessary for manifestation of the AAS effect. The synergistic effects of adding chlorinated cobalt dicarbollide (CCD) with the DPDO that has been reported for other systems was also found to prevail in several of the systems investigated in this study. On addition of CCD with the DPDO, a considerable synergistic effect is observed (DAm increases by three to four orders of magnitude) during Am and Eu extraction from nitrate media, in perchlorate media the synergistic effect is absent. The most probable reason for synergism in the presence of CCD is the higher... [ABSTRACT FROM AUTHOR]