Solubility of Neptunium(IV) Hydrous Oxide in Aqueous Solutions

Nakayama, Shinichi; Yamaguchi, Tetsuji; Sekine, Keiichi

doi:10.1524/ract.1996.74.special-issue.15

Cited by 21 publications

(14 citation statements)

References 5 publications

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“…Compared with the present case of U(IV), the solubilities of Th(IV) [13], Np(IV) [14][15][16] and Pu(IV) [17] have been reported to be constant at high pH, suggesting no predominant formation of penta-and hexahydroxide complexes up to pH 13-14. It is thus interesting to study different behaviors of actinides.…”

Section: Comparison With Literature Datacontrasting

confidence: 69%

Solubility of uranium(IV) hydrous oxide in high pH solution under reducing condition

Fujiwara¹,

Yamana²,

Fujii³

et al. 2005

Radiochimica Acta

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The solubility of uranium(IV) hydrous oxide was measured at 25 • C in NaClO 4 solution containing Na 2 S 2 O 4 as a reducing agent in the pH range from 12 to 14. The experiment was carried out from oversaturation at I = 0.5, 1.0 and 2.0 mol/dm 3 (M). The solubility data were analyzed to obtain the hydrolysis constants (β m ) of U(OH) m (4−m) . By taking the specific ion interaction theory (SIT) for ionic strength corrections and by using the solubility product log K • sp = −53.93 ± 0.20, the hydrolysis constants at I = 0, log β • 5 < 48.10 and log β • 6 = 48.95 ± 1.01, were determined together with the ion interaction coefficients of U(OH) 5 − and U(OH) 6 2− .

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Section: Comparison With Literature Datacontrasting

confidence: 69%

Solubility of uranium(IV) hydrous oxide in high pH solution under reducing condition

Fujiwara¹,

Yamana²,

Fujii³

et al. 2005

Radiochimica Acta

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“…Figures 4 and 5 present similar comparisons of the predicted solubility curves with the experimental results of Np(IV) [29][30][31][32] and Pu(IV), 15,[33][34][35][36] Rai et al 27) As shown in Figs. 4 and 5, the predicted solubility curves are again consistent with the experimental data in acidic region.…”

Section: Speciessupporting

confidence: 62%

Systematics of Hydrolysis Constants of Tetravalent Actinide Ions

Moriyama

Sasaki

Kobayashi

et al. 2005

Journal of Nuclear Science and Technology

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Systematic trends of mononuclear and polynuclear hydrolysis constants of tetravalent actinide ions were analyzed by using an electrostatic hard sphere model. The effective charges of actinide ions were introduced into the model by considering possible contributions of non-electrostatic interactions of actinide ions in addition to those of ordinary electrostatic ones. The systematic trends of hydrolysis constants were well fitted by the present model, and the parameter values such as the effective charges of actinide ions were determined. Some predictions were made and discussed in comparison with the solubility curves of tetravalent actinides.

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“…In the experiments for Np(IV), a Np(IV) stock solution was prepared as 22 mol m −3 (2.2 × 10 −2 M or 1.36 × 10 11 Bq m −3 ) 237 Np(IV) dissolved in 10 3 mol m −3 (1 M) HCl [14]. The starting solutions were prepared under a controlled Ar atmosphere (< 1 ppm O 2 ) and added with Na 2 S 2 O 4 to eliminate the oxidation of Np(IV) by atmospheric O 2 .…”

Section: Methodsmentioning

confidence: 99%

Interactions between anionic complex species of actinides and negatively charged mineral surfaces

Yamaguchi¹,

Nakayama²,

Yoshida³

2004

Radiochimica Acta

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Sorption of actinides onto negatively charged mineral surfaces was investigated under conditions that actinides were predominantly present as anionic complex species. U(VI), Np(V) and Sn(IV) were prepared as 1 mol kg −1 Na-ClO 4 /OH solutions and equilibrated with γ -Al 2 O 3 at pcH 11-13.6 where these elements form UO 2 (OH) 4 2− , NpO 2 (OH) 2 − and Sn(OH) 5 − species, respectively. Sorption of Np(IV), Th(IV) and Am(III) on amorphous SiO 2 and on γ -Al 2 O 3 was investigated in 0.03-0.3 mol kg −1 Na-HCO 3 /CO 3 solutions where these actinides are expected to be stable as anionic carbonate complexes. Distribution coefficients of U(VI), Np(V), Sn(IV), Th(IV) and Am(III) decreased with the increasing pH or with the increasing carbonate concentrations. The monotonous decrease in the distribution coefficients in the investigated pcH range suggests that anionic complex species of actinides were not sorbed on negatively charged mineral surfaces. A proportional relation was found between the experimentally obtained K d values and calculated mole fraction of electrically neutral species in equilibrated solutions. Sorption occurs under the condition that both actinides and mineral surfaces are negatively charged because minor neutral species are sorbed on mineral surfaces.

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Solubility of Neptunium(IV) Hydrous Oxide in Aqueous Solutions

Cited by 21 publications

References 5 publications

Solubility of uranium(IV) hydrous oxide in high pH solution under reducing condition

Solubility of uranium(IV) hydrous oxide in high pH solution under reducing condition

Systematics of Hydrolysis Constants of Tetravalent Actinide Ions

Interactions between anionic complex species of actinides and negatively charged mineral surfaces

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