Neptunium V

Neptunium V sorption on hematite (a-Fe20 ) in aqueous suspension the effect of CO2. Radiochim. Acta 85 3348 Kolb, E.D. Caporaso, A.J. Laudise, R.A. 

Combes, J. M., Chisholm-Brause, C. J. et al. 1992. EXAFS spectroscopic study of neptunium(V) sorption at the a-FeOOH/water interface. Environmental Science and Technology, 26, 376-382. 

DelNero, M., Made, B., Bontems, G. Clement, A. 1997. Adsorption of neptunium(V) on hydrargilite. Radiochimica Acta, 76, 219-228. 

Del Nero, M., Advocat, T., Jollivet, P. Bontems, G. 1999b. Sorption of neptunium (V) on an alteration gel of alumino-borosilicate glasses and on synthetic silicate gels. Proceedings 2nd International Symposium on Nuclear Fuel Cycle Safety Engineering Research Facility NUCEF 98, Hitachinaka, Ibaraki, Japan, 584-595. 

Table 49 Some Hydrates of Protactinium(V), Uranium(V), Neptunium(V) and Plutonium(V)...

Hydroxides and oxides. Protactinium(V), neptunium(V) and plutonium(V) hydroxides precipitate from alkaline aqueous solutions of the actinides(V) the last two appear to be of the form Mv02(0H)-xH20. 

The only compounds with this type of ligand appear to be the hydrated neptunium(V) complexes with ethylenediaminetetraacetic acid (H4edta), (Np02)2H2(edta)-5H20 and [Co(NH3)6]Np02(edta) -3H20. 

The chlorocomplex salt, Cs3fAm02Cl4], is isostructural with the analogous neptunium(V) and plutonium(V) compounds.206 Its vibrational spectrum has also been reported.185... 

In summary, the solubility and sorption reactions of cobalt, strontium, neptunium, plutonium, and americium were found to be dependent on HLW compositions. Evidence revealed the formation in HLW of organic complexes of cobalt, strontium, and americium, and of hydroxide complexes of neptunium(V) and plutonium(V). Sorption reactions were dependent on radioelement complex formation and suspected waste/sediment reactions. These data can aid in assessing effects of future HLW processing operations as well as in judging the feasibility of continued storage of HLW in existing tanks. 

Np (V) (3) and Pu (V) (8), the last two being the first non-oxygenated neptunium (V) and plutonium (V) compounds. Some of the preparative procedures used for uranium (V) fiuoro complexes are shown in Table IV. 

Alkali metal dioxofluorides of the type A M02F2 (M = Np, Pu (64) and Am (2, 64) have been prepared from aqueous solution and chloro complex salts of neptunium (V) (24) and americium (V) (25) are now... 

A few derivatives of oxyanions have also been prepared protactinium (V) forms hexanitrato complexes, Pa(N03)e , by reaction of the hexachloro complex with dinitrogen pentoxide, in contrast to niobium and tantalum which, under similar conditions, yield only tetranitrato complexes, M0(N03)4 (35). Neptunium (V) nitrates, NPO2NO3 and Np0(N03)3 have also been reported 71). Protactinium (V) sulfato-and selenato complex acids, H3PaO( 804)3 and H3Pa0(Se04)3, have been obtained from aqueous solution (13), but no fully sulfated or sele-nated species have been recorded. 

Much less work has been reported for the 6-valent elements as compared with the volume of literature for the actinides in lower valence states. Hydrated neptunium and plutonium trioxides are now known, Np03 H2O and PUO3 (0.8)H2O being readily obtained by the action of ozone on an aqueous suspension of neptunium (V) or plutonium (IV) hydroxides at 90°C. (23) Np03 2H2O is obtained in a similar manner at 18°C. (23) or by ozone oxidation of neptunium (V) in a molten lithium-potassium nitrate eutectic at 150°C. (42). 

Table IV. Some Alkali Fluoride Protactinium ( V ), Uranium ( V ), Neptunium(V), Plutonium(V) Fluoride Complexes"...

Kim J. I. and Sekine T. (1991) Complexation of neptunium(V) with humic-acid. Radiochim. Acta 55(4), 187-192. 

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