Complexation of plutonium(IV) with sulfate at variable temperatures

Xia, Yafeng; Friese, Judah I.; Moore, Dean A.; Bachelor, Paula P.; Rao, Linfeng

doi:10.1007/s10967-006-6907-z

Cited by 16 publications

(22 citation statements)

References 17 publications

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“…In contrast to the cation effect, the addition of certain anions had a significant influence on K d values; the sorption of Pu was strongly influenced by adding SO 4 2− and CO 3 2− . A similar result was reported by Xia et al [36], who concluded that "the distribution ratio of Pu(IV) between the organic and aqueous phases was found to decrease as the concentrations of sulfate were increased". On the other hand, the effects on Pu sorption by NO 3 − and Cl − were weak.…”

Section: Influence Of Different Ions (Cations and Anions)supporting

confidence: 87%

Factors influencing plutonium sorption in shale media

et al. 2010

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Plutonium / Sorption / Distribution coefficient / Grain size / pH / Water/solid ratio / ComplexationSummary. The extent and factors influencing sorption of plutonium (Pu) in shale media have been studied in batchtype experiments. The equilibrium time and isotherm of Pu sorption have been firstly determined. The effect of shale grain size, aqueous pH, water/solid ratio, co-existing ions (cations and anions) and temperature were studied as the factors likely to influence Pu sorption. The experimental variables included the following: grain sizes in five ranges, 0.12 to 0.15 mm, 0.15 to 0.18 mm, 0.18 to 0.25 mm, 0.25 to 0.38 mm, and 0.38 to 0.83 mm; solution pH values of 4, 6, 8, and 10; water/solid ratios of 10 : 0.25, 10 : 0.5, 10 : 0.75, and 10 : 1; temperatures of 20 • C, 40 • C, and 60 • C); and selected coexisting conventional cations including Na + , Fe + , Al 3+ , Ca 2+ , and K + and anions including SO 4 2− , CO 3 2− , NO 3 − , and Cl − in each case in solutions of the same total ionic strength. The experimental results demonstrate that the equilibrium time of Pu sorption is 9 d, that the sorption behavior of Pu in the solution is well described by the Freundlich sorption isotherm (C s = kC N eq ), and that Pu is strongly sorbed on shale media. The extent of Pu sorption increased with decreasing grain size, apparently in response to the increase in specific surface area and total pore volume. The results also show that Pu sorption increases with increasing solution pH and with increasing water/solid ratio. The influence of co-existing anions on Pu sorption was much stronger, under the same conditions, than that of the cations; this was attributed to Pu complexation in solution, i.e., the complexing apparently weakened the sorption of Pu on shale particles in the solution. Finally, the influence of varying temperature on Pu sorption is found to be less important than that of other factors, but should never be ignored.

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Section: Influence Of Different Ions (Cations and Anions)supporting

confidence: 87%

Factors influencing plutonium sorption in shale media

et al. 2010

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“…''H 2 O'' would also include hydrogen bonded proton networks, giving Pu-O bond lengths differing from those found in solution and contributing to the asymmetric/anharmonic O distribution around the 2.33 Å principal crystallographic shell. Inclusion of protonated species in the initially formed precipitates would be expected, and their subsequent elimination and ordering of the lattice is undoubtedly related to the ripening process [4,[35][36][37][38] that causes the solubility constants to change by orders of magnitude over time. These directly coordinated near neighbor O shells with shorter Pu-O distances are supplemented by longer Pu-O distances that result from the mirroring of these displacements on the neighboring Pu atoms.…”

Section: Complex Pu-o Distributions In Conventionally Prepared Materialsmentioning

confidence: 99%

Charge distribution and local structure and speciation in the UO2+x and PuO2+x binary oxides for x⩽0.25

Conradson

Begg

Clark

et al. 2005

Journal of Solid State Chemistry

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“…In recent studies, equilibrium constants and the enthalpy of complexation have been determined for U(VI)/sulfate complexes by spectrophotometry (16), for Np(V)/sulfate complexes by spectrophotometry (14,18) and solvent extraction (13), and for Pu(IV)/sulfate complexes by solvent extraction (19), in the temperature range from 25 to 70 o C. The data are summarized in Table III and discussed below. …”

Section: Complexation Of Actinides With Sulfate At Variable Temperaturesmentioning

confidence: 99%

“…The complexation of plutonium(IV) with sulfate at variable temperatures from 25 o C to 55 o C has been investigated by the solvent extraction method (19). The decrease of the distribution ratio of Pu(IV) between the organic and aqueous phases was interpreted as being due to the formation of 1:1 and 1:2 Pu(IV)-SO 4 2-complexes in the aqueous phase and the stability constants of Pu(SO 4 ) 2+ and Pu(SO 4 ) 2 (aq) at different temperatures were accordingly calculated.…”

Section: Pu(iv)/sulfatementioning

confidence: 99%

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Bridging the Gap in the Chemical Thermodynamic Database for Nuclear Waste Repository: Studies of the Effect of Temperature on Actinide Complexation

Rao¹

2010

ACS Symposium Series

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Recent results of thermodynamic studies on the complexation of actinides (UO 2 2+ , NpO 2 + and Pu 4+ ) with F -, SO 4 2-and H 2 PO 4 -/HPO 4 2-at elevated temperatures are reviewed. The data indicate that, for all systems except the 1:1 complexation of Np(V) with HPO 4 2-, the complexation of actinides is enhanced by the increase in temperature. The enhancement is primarily due to the increase in the entropy term (TΔS) that exceeds the increase in the enthalpy (ΔH) as the temperature is increased. These data bridge the gaps in the chemical thermodynamic database for nuclear waste repository where the temperature could remain significantly higher than 25 o C for a long time after the closure of the repository.

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Complexation of plutonium(IV) with sulfate at variable temperatures

Cited by 16 publications

References 17 publications

Factors influencing plutonium sorption in shale media

Factors influencing plutonium sorption in shale media

Charge distribution and local structure and speciation in the UO2+x and PuO2+x binary oxides for x⩽0.25

Bridging the Gap in the Chemical Thermodynamic Database for Nuclear Waste Repository: Studies of the Effect of Temperature on Actinide Complexation

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