Kinetics and mechanisms of redox reactions of U, Pu, and Np in tributyl phosphate solutions

Marchenko, V. I.; Koltunov, V. S.; Dvoeglazov, K. N.

doi:10.1134/s1066362210020013

Cited by 19 publications

(13 citation statements)

References 21 publications

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“…[32] There is no information in the literature on the reverse reaction in the organic phase; it was assumed that this did not proceed at any significant rate. [33] NpðVÞ …”

Section: Modeling Of Neptunium Redox Reaction Kineticsmentioning

confidence: 99%

Development and Validation of a Flowsheet Simulation Model for Neptunium Extraction in an Advanced PUREX Process

Chen

Taylor

Jobson

et al. 2016

Solvent Extraction and Ion Exchange

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An Advanced PUREX process has been developed for separation and recycling of neptunium from spent nuclear fuel. This work presents a new flowsheet simulation model for the extraction of neptunium using centrifugal contactors, where mass transfer is modeled using two-film theory and a linear driving force. Distribution coefficients and neptunium redox reactions are modeled using published models. Mass transfer between the organic and aqueous phases in the phase separation zone is shown to have a negligible effect. The model is applied to a previously tested flowsheet and its predictions are shown to be in good agreement with the experimental results.

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“…[32] There is no information in the literature on the reverse reaction in the organic phase; it was assumed that this did not proceed at any significant rate. [33] NpðVÞ …”

Section: Modeling Of Neptunium Redox Reaction Kineticsmentioning

confidence: 99%

Development and Validation of a Flowsheet Simulation Model for Neptunium Extraction in an Advanced PUREX Process

Chen

Taylor

Jobson

et al. 2016

Solvent Extraction and Ion Exchange

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“…[8] to [13] are kinetics equations of oxidation Np(V) by nitric acid, and the Ref. [14] to [15] are that of reduction Np(VI) by nitrous acid.…”

Section: Kinetics Equationmentioning

confidence: 99%

“…(13) the value of a and b are obtained, and then k f and k r can be calculated according to Eqs. (10) to (13). In order to simplify the data processing, the phase ratio R of 1:1 was used in our all experiments.…”

Section: Kinetic Equationmentioning

confidence: 99%

“…Although many researchers have investigated the chemical reaction of Np in aqueous solution [8][9][10][11][12][13][14][15][16][17], but a full understanding of the complex and dynamic Np process chemistry in the TBP-HNO 3 system is necessary. This process includes reversible reaction of Np(VI)/Np(V) and extraction of neptunium between two phase of TBP-HNO 3 simultaneously, which is obviously different from purely aqueous phase chemical reaction.…”

Section: Introductionmentioning

confidence: 99%

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The complex reaction kinetics of neptunium including redox and extraction process in 30% TBP—nitric acid system

Zhang

Liu

Zhou

et al. 2017

J Radioanal Nucl Chem

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In order to understand the complex and dynamic neptunium process chemistry in the TBP-HNO 3 system, the kinetics involved reversible redox reaction and extraction mass transfer was investigated. The results indicates that the mass transfer rate of Np(VI) is much faster than the redox reaction in aqueous solution. The concentrations of nitric acid and nitrous acid not only can change the Np(V) oxidation reaction and Np(VI) reduction reaction rate, but also can ultimately determine the distribution of neptunium extraction equilibrium. The variety of temperature can only influence the extraction equilibrium time, but cannot alter the equilibrium state of neptunium.

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“…These ions affect the disproportionation reaction depending on their activity and complexing ability, which involves multiple reaction paths [4,6,7]. There was a significant enhancement in the disproportionation rate of Np(V) in non-aqueous media having lower dielectric constants as compared to that of aqueous solutions [8][9][10]. Recently, Sarsfield et al observed that Np(V) was unstable in 30% (v/v) tributyl phosphate (TBP) dissolved in kerosene and disproportionated to form Np(IV) and Np(VI).…”

Section: Introductionmentioning

confidence: 99%

Redox Behavior of Neptunium(V) in Tributyl Phosphate and N,N-Dihexyl Octanamide Extractants Dissolved in n-Dodecane

et al. 2012

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Spectrophotometric investigations have been carried out on the disproportionation of Np(V) to form Np(IV) and Np(VI) in 1.1 mol·L −1 solutions of tributyl phosphate (TBP) and in N,N-dihexyl octanamide (DHOA) in n-dodecane medium. The Np(V) was found to coordinate with Np(IV) in 1.1 mol·L −1 TBP solution in n-dodecane to form a mixed valence "cation-cation" complex by bonding through an axial oxo group on Np(V). By contrast, this interaction was less prominent in the case of 1.1 mol·L −1 DHOA solutions. The effect of 1-octanol, added as phase modifier, on the disproportionation behavior of Np(V) was also investigated. An attempt was made to calculate the disproportionation/reduction rate constants for Np(V) under the conditions of these studies. Absorbance measurements on the Np stripped from organic phases revealed the occurrence of Np(V) in the aqueous phase.

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Kinetics and mechanisms of redox reactions of U, Pu, and Np in tributyl phosphate solutions

Cited by 19 publications

References 21 publications

Development and Validation of a Flowsheet Simulation Model for Neptunium Extraction in an Advanced PUREX Process

Development and Validation of a Flowsheet Simulation Model for Neptunium Extraction in an Advanced PUREX Process

The complex reaction kinetics of neptunium including redox and extraction process in 30% TBP—nitric acid system

Redox Behavior of Neptunium(V) in Tributyl Phosphate and N,N-Dihexyl Octanamide Extractants Dissolved in n-Dodecane

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