Actinide acetates, anion

Anion Exchange and Amine Extraction of Hexavalent Actinide Acetates... 

Spectrophotometric studies were used to identify the anionic hexavalent actinide acetate complexes present in aqueous and nonaqueous solutions, anion exchange resins, and amine extracts. The previously unreported tetraacetate complexes, M02(CJd 0i),, were identified in all these systems. The formation constant for the reaction +... 

The triacetate uranyl complex (24) is structurally similar to the trinitrate uranyl complex (6) (three bidentate ligands arranged equa-torially around the uranyl O—U—O axis). It was expected that the visible, near ultraviolet spectrum of the triacetate uranyl complex would be similar to the spectrum of U02(N03)3 as are the spectra of 1102(804)3, 1102(003)3 , and other uranyl complexes which apparently have the same structure (17). The absorption spectrum of uranyl acetate extracted into tri-n-octylamine in xylene from dilute acetic acid is different from the trinitrato uranyl spectrum. This indicates that the triacetate uranyl complex is probably not the species involved. By analogy to the uranyl nitrate system 14), formation of a tetraacetate uranyl complex might be expected. The purpose of this work is to determine the nature of the anionic hexavalent actinide acetate complexes and to identify the species involved in the amine extraction and anion exchange of the hexavalent actinides from acetate systems. 

The ionization of Lr would be expected to stop with the f- core intact because of the enhanced binding energy of possible valence electrons in the filled f shell. The stable valence state of Lr would then be the (III) state. Experiments to confirm this oxidation state of Lr were undertaken by Silva and coworkers (1). They compared the extraction behavior of Lr with several tri- and tetravalent actinides and with Ba +, Ra +, and No +. A chelating extractant, thenoyltrifluoroacetone dissolved in methyl isobutyl ketone, was employed to extract the tracer ions from aqueous solutions that had been buffered with acetate anions. Their results, shown in Figure 8, very clearly demonstrate that Lr is extracted within the same pH range as the trivalent actinides, and therefore, proves that Lr is trivalent. 

Basicity of some common anions relative to the (hard type) actinide cations CIO4 < I < Br < Cr < no < SCN < acetate <... 

The Au foil Is quickly dissolved In aqua regia and the Au extracted with ethyl acetate for 1 min. The aqueous phase is then eluted through a Dowex-1 anion resin column (2 zmn diameter, 1 cm long) with 6 M HC1 to complete the removal of Au end other impurities. The dropB. containing the actinide fraction are evaporated and the activity is then eluted through a Dowex-50 resin cation column with 0.4 M soln. of ammonium Q -hydroxy-isobutyrate, which is adjusted to pH 4.0 with HH4OH to separate the various actinide elements from each other, (Mv-Fm-E-Cf)... 

The actinide (VI) acetate system discussed here and the actinide (VI) sulfate system to be discussed later (17) represent the only cases known to us in which observable mixtures of labile anionic complexes of a given metal are extracted from an acid solution by susbtituted amines. The present system represents the only one in which the diluent is the only major factor controlling the ratio of species in the organic phase. The principle mechanism by which the nature of the diluent appears to determine the ratio of species in the organic phase in this system is by... 

The actinide ions in aqueous solution resemble the tripositive lanthanide ions in their precipitation reactions, allowing for differences in the redox properties of early members of the actinide series. The chloride, bromide, nitrate, bromate, and perchlorate anions form water-soluble salts, which can be isolated as hydrated solids by evaporation. The acetates, iodates, and iodides are somewhat less soluble in water. The sulfates are sparingly soluble in hot solutions, somewhat more soluble in the cold. Insoluble precipitates are formed with hydroxide, fluoride, carbonate, oxalate, and phosphate anions. Precipitates formed from aqueous solution are usually hydrated, and the preparation of anhydrous salts from the hydrates without formation of hydrolyzed species can only be accomplished with difficulty. The actinide(iv) ions resemble Ce(iv) in forming fluorides and oxalates insoluble even in acid solution. The nitrates, sulfates, perchlorates, and sulfides are all water-soluble. The iv state actinide ions form insoluble iodates and arsenates even in rather strong acid solution. The... 

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