Higher Oxidation States of Americium: Preparation, Characterization and Use for Separations

Runde, Wolfgang; Mincher, Bruce J.

doi:10.1021/cr100181f

Cited by 112 publications

(109 citation statements)

References 131 publications

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“…The transuranic element americium presents a long-term radiotoxicity hazard in the disposal of high-level waste (HLW) resulting from production of nuclear power [1,2]. This is driven primarily by the isotope 241 Am, which has a half-life of 430 years.…”

Section: Introductionmentioning

confidence: 99%

Americium(III) oxidation by copper(III) periodate in nitric acid solution as compared with the action of Bi(V) compounds of sodium, lithium, and potassium

Sinkov¹,

Lumetta²

2015

Radiochimica Acta

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The oxidative action of a Cu(III) periodate compound toward Am(III) in nitric acid was studied. The extent of oxidation of Am(III) to Am(VI) was investigated using a constant initial Cu(III)-to-Am(III) molar ratio of 10 : 1 and varying nitric acid concentrations from 0.25 to 3.5 mol/L. From 0.25 to 3 mol/L HNO 3 , more than 98% of the Am(III) was oxidized to Am(VI); however, at 3.5 mol/L HNO 3 , the conversion to Am(VI) was only 80%. Increasing the Cu(III)-to-Am(III) molar ratio to 20 : 1 in 3.5 mol/L HNO 3 resulted in 98% conversion to Am(VI). For comparison, oxidation of Am(III) with NaBiO 3 was studied at 3.5 mol/L HNO 3 and the same stoichiometric excess of Bi(V) oxidant over Am(III) (stoichiometric ratio of 3.33 : 1). With NaBiO 3 , the extent of Am(III) conversion to Am(VI) was only 19%, while with the Cu(III) compound this value was found to be about 4 times higher under otherwise identical conditions. Similar results were obtained with other Bi(V) salts. These results show that the Cu(III) periodate compound is a superior oxidant to NaBiO 3 , yielding rapid conversion to Am(VI) in a homogeneous acidic solution, and is, therefore, an excellent candidate for further development of Am separation systems.

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Section: Introductionmentioning

confidence: 99%

Americium(III) oxidation by copper(III) periodate in nitric acid solution as compared with the action of Bi(V) compounds of sodium, lithium, and potassium

Sinkov¹,

Lumetta²

2015

Radiochimica Acta

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“…The spectrum of Am(VI) in acid media is almost not affected by changes in the nature of the anions. Only negligible shifts of the AmO 2+ 2 peak position occur in the H 2 SO 4 , HNO 3 , H 3 PO 4 solutions [28]. In carbonate solution, the absorption band of Am(VI) is shifted markedly to 1000 nm [29].…”

Section: Absorption Spectramentioning

confidence: 99%

Americium dioxocations in solid: crystal structures and absorption spectra of the new complexes [Am^VO₂(dipy)OOCCH₃(H₂O)] and Cs₂[(Am^VIO₂)₂(SO₄)₃]

2014

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Single crystals of the two new compounds [Am V O 2 (dipy)OOCCH 3 (H 2 O)] (I) and Cs 2 [(Am VI O 2 ) 2 (SO 4 ) 3 ] (II) have been synthesized and their structures have been determined by X-ray structural analysis. IR and optical spectra of polycrystalline compounds I and II were measured and interpreted. The structure I is formed by electroneutral complexes [Am V O 2 (dipy)OOCCH 3 (H 2 O)], in which dioxocations AmO 2 + are coordinated by two N atoms of a bidentate-chelating dipy ligand, two O atoms of a bidentate-chelating acetate anion and one O atom of water molecule. Due to a different nature of ligands, the distances and bond angles in the equatorial plane of AmO + 2 have a significant spread. The structure II is built of interlaced anionic and cationic layers. Anionic layers [(Am VI O 2 ) 2 (SO 4 ) 3 ] 2 − contain AmO 2 2+ groups and two types of SO 4 2− anions: tridentate-and tetradentatebridging. Each AmO 2 2+ is coordinated in a monodentate way by three tridentate anions and two tetradentate ones. The coordination numbers of the outer Cs + cations are equal to 10 for Cs(1), and 16 for Cs(2). The dioxocations AmO 2 in both structures are linear and almost symmetric.Analysis of the obtained absorption spectra showed that the number and intensity of the absorption bands in them are dependent both on the equatorial ligand nature, and on the americium ion electronic configuration.

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“…In fact, a brown film was visible on the bottom of the cuvette at the end of the experiment. [5]), irradiated in the nominal absence of residual bismuthate solid. It can be seen that the absorbance at 997 nm decreased rapidly with absorbed dose until after exposure to 0.3 kGy no AmVI was detectable.…”

Section: Samples Nominally Containing Only Trace Residual Bismuthatementioning

confidence: 99%

The Radiolysis of AmVI Solutions

Mincher¹

2013

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SUMMARYThe reduction of bismuthate-produced AmVI by 60 Co gamma-rays was measured using post-irradiation UV/Vis spectroscopy. The reduction of AmVI by radiolysis was rapid, producing AmV as the sole product. Relatively low absorbed doses in the ~0.3 kGy range quantitatively reduced a solution of 2.5 x 10 -4 M AmVI. The addition of bismuthate to samples during irradiation did not appear to protect AmVI from radiolytic reduction during these experiments. It was also shown here that AmV is very stable toward radiation. The quantitative reduction of the AmVI concentration here corresponds to 1.4 hours of exposure to a process solution, however the actual americium concentrations will be higher and the expected contact times short when using centrifugal contactors. Thus, the reduction rate found in these initial experiments may not be excessive.

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Higher Oxidation States of Americium: Preparation, Characterization and Use for Separations

Abstract: 5729 4. Redox Potentials and Thermodynamic Properties 5730 4.1. Am(IV)/(III) 5730 4.2. Am(V)/Am(III) 5731 4.3. Am(VI)/Am(III) 5731 4.4. Am(VI)/(V) 5731 4.5. Am(VII)/(VI) 5731 4.6. Thermodynamic data for Am(IV), Am(V), and

Cited by 112 publications

References 131 publications

Americium(III) oxidation by copper(III) periodate in nitric acid solution as compared with the action of Bi(V) compounds of sodium, lithium, and potassium

Americium(III) oxidation by copper(III) periodate in nitric acid solution as compared with the action of Bi(V) compounds of sodium, lithium, and potassium

Americium dioxocations in solid: crystal structures and absorption spectra of the new complexes [Am^VO₂(dipy)OOCCH₃(H₂O)] and Cs₂[(Am^VIO₂)₂(SO₄)₃]

The Radiolysis of AmVI Solutions

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Higher Oxidation States of Americium: Preparation, Characterization and Use for Separations

Abstract: 5729 4. Redox Potentials and Thermodynamic Properties 5730 4.1. Am(IV)/(III) 5730 4.2. Am(V)/Am(III) 5731 4.3. Am(VI)/Am(III) 5731 4.4. Am(VI)/(V) 5731 4.5. Am(VII)/(VI) 5731 4.6. Thermodynamic data for Am(IV), Am(V), and

Cited by 112 publications

References 131 publications

Americium(III) oxidation by copper(III) periodate in nitric acid solution as compared with the action of Bi(V) compounds of sodium, lithium, and potassium

Americium(III) oxidation by copper(III) periodate in nitric acid solution as compared with the action of Bi(V) compounds of sodium, lithium, and potassium

Americium dioxocations in solid: crystal structures and absorption spectra of the new complexes [Am V O2(dipy)OOCCH3(H2O)] and Cs2[(Am VI O2)2(SO4)3]

The Radiolysis of AmVI Solutions

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Americium dioxocations in solid: crystal structures and absorption spectra of the new complexes [Am^VO₂(dipy)OOCCH₃(H₂O)] and Cs₂[(Am^VIO₂)₂(SO₄)₃]