Actinide nitrato complexes

The largest number of automated extraction-chromatographic separations for actinides have used TRU-Resin, and many of these have coupled the column to ICP-MS as an on-line separation (see Table 9.3). TRU-Resin is impregnated with the neutral bifunctional organophosphorus complexant, octyl(phenyl)-A,A-diisobu-tylcarbamoylmethylphosphine oxide (CMPO) in tri-n-butyl phosphate (TBP).26 127 128 The organic stationary phase in this resin binds trivalent, tetravalent, and hexavalent actinide nitrato complexes from nitric acid solutions (see Figure 9.11). The extraction equilibria for representative species are shown in Equations 9.3-9.5, where the bar above a species indicates that it is immobilized on the resin.4... 

TEVA-Resin is an extraction-chromatographic material based on Aliquat 336, which is a liquid quaternary ammonium salt, as described previously in connection with "Tc separations.30 It acts as a strongly basic anion-exchange material, retaining tetravalent actinides from 2-4 M HN03 solutions as anionic nitrato complexes (see Figure 9.11). Am(III), Np(V), and U(VI) are much less retained. The extraction... 

The results of solid state reactions of protactinium dioxide and pentoxide with other metal oxides (89, 93-96) support the view that the oxide systems of protactinium resemble those of other actinide elements rather than those of niobium and tantalum. However, when assessing results of this type one must always bear in mind the relative ionic radii of the respective M " and M + ions since they obviously play a large part in determining the structures of the complex phases. This comment applies equally well, of course, to the structural properties of other types of compound and in particular to the high coordination numbers exhibited by protactinium(V) in its chloro and nitrato complexes. 

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