Plutonium ions

Absorption Spectra, of Aqueous Ions. The absorption spectra of Pu(III) [22541-70 ] Pu(IV) [22541 4-2] Pu(V) [22541-69-1] and Pu(VI) [22541-41-9] in mineral acids, ie, HCIO and HNO, have been measured (78—81). The Pu(VII) [39611-88-61] spectmm, which can be measured only in strong alkaU hydroxide solution, also has been reported (82). As for rare-earth ion spectra, the spectra of plutonium ions exhibit sharp lines, but have larger extinction coefficients than those of most lanthanide ions (see Lanthanides). The visible spectra in dilute acid solution are shown in Figure 4 and the spectmm of Pu(VII) in base is shown in Figure 5. The spectra of ions of plutonium have been interpreted in relation to all of the ions of the bf elements (83). 

The chemistry of plutonium ions in solution has been thoroughly studied and reviewed (30,94—97). Thermodynamic properties of aqueous ions of Pu are given in Table 8 and in the Uterature (64—66). The formal reduction potentials in aqueous solutions of 1 Af HCIO or KOH at 25°C maybe summarized as follows (66,86,98—100) ... 

Radiolysis creates oxidants such as the OH radical and reductants such as e (aq), which oxidize or reduce plutonium ions. Self-radiolysis of Pu... 

Table 10. Spectral Absorption Data for Aqueous Plutonium Ions at 25°C ...

Reactions of Plutonium Ions with the Products of Water Radiolysis... 

The reactions to be expected between the radicals produced by the radiation of H2O with the plutonium ions in aqueous... 

Electronic absorption spectra, of plutonium ions, 19 693-694, 695 Electronically erasable nonvolatile... 

Plutonium compounds, 19 687-691 protection against, 19 702 Plutonium dioxide, 19 688—689 Plutonium fuel fabrication facilities, 17 547 Plutonium-gallium alloys, 19 683-684 Plutonium halides, 19 689-690 Plutonium hexafluoride, 19 689 Plutonium hydrides, 19 690 Plutonium ions... 

The aqueous chemistry of plutonium is dictated by two factors its tendency to hydrolyse and its tendency to form complexes. As the plutonium ions have a high charge and relatively small ionic radius they all exhibit a strong tendency to hydrolyse quite rapidly. Kraus (9) has shown that the tendency to hydrolyse follows the order ... 

As trivalent americium has a smaller ionic potential than the ions of plutonium it hydrolyses to a much lesser extent than the various plutonium ions. However, like Pu3+, hydrolytic reactions and complex formation are still an important feature of the aqueous chemistry of Am3+. Starik and Ginzberg (25) have shown that Am(III) exists in its ionic form from pH 1.0 to pH 4.5 but above pH 4.5 hydrolysis commences and at pH 7.0 colloidal species are formed. The hydrolytic behaviour of Cm(III) resembles that of Am(III). 

The electrochemical behavior of plutonium ions in alkaline media has received substantially less literature coverage in comparison to results in acidic solutions. 

The plutonium ions in aqueous solution possess characteristic colors bluc-lavcndcr for Pu3+. yellow-brown to green for Pu4+, and pink-orange for Pu02 +. 

Calculated concentrations of possible hydrolysis species as a function of the equilibrium pH are given in Figures 6 and 7 for americium ions and plutonium ions, respectively. In the americium solution, the predominant species at pH <7 are the Am3+ and Am(OH)2+ ions, whereas in the plutonium solution the Pu022+ ion is not the dominating species at near neutral media but polymers as postulated (Pu02)2(OH)22+ and(Pu02)3(0H)5+. 

Americium Feed Adjustment. The aqueous americium-bearing, sodium nitrate/sulfate-nitric acid solution was evaporated and acid-stripped. Oxalic acid was added to complex iron and plutonium ions before feeding to a cation exchange column. 

From our tracer experiments, the distribution coefficient of Pu(IV) is directly proportional to [HDEHP]2 and is inversely proportional to [H+]2. The capacity experiments show that there are four molecules of HDEHP and one plutonium ion in a molecule of extracted compound. From this, we conclude that HDEHP is a dimer in the concentration range studied. The proposed extraction mechanism is as follows ... 

Silver, G. L. Effect of Hydrolysis on the Disproportionation of Tetravalent and Pentavalent Plutonium Ions, U.S. AEC Report MLM-1743, Mound Laboratory, Miamisburg, OH, 1970. 

Foreman, J. K., and Smith, T. D. The nature and stability of the complex ions formed by ter-, quadri-. and sexa-valent plutonium ions with ethylenediaminetetraacetic acid. Part I. pH titrations and ion exchange studies, J. Chem. Soc.,... 

Cauchetier, P., and Guichard, C. Electrochemical and spectro-photometric study of the complexes of plutonium ions with EDTA. I. Plutonium(III) and (IV), Radiochim. Acta, 19, 137 (1973). 

Kabanova, 0. L., Danuschenkova, M. A., and Paley, P. N. The reactions of plutonium ions with ethylenediaminetetraacetic acid. Anal. Chim. Acta, 22, 66 (1960). 

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