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Conrad JK, Mezyk SP, Isherwood LH, Baidak A, Pilgrim CD, Whittaker D, Orr RM, Pimblott SM, Horne GP. Gamma Radiation-Induced Degradation of Acetohydroxamic Acid (AHA) in Aqueous Nitrate and Nitric Acid Solutions Evaluated by Multiscale Modelling. Chemphyschem 2023; 24:e202200749. [PMID: 36470592 DOI: 10.1002/cphc.202200749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/11/2022] [Indexed: 12/12/2022]
Abstract
Acetohydroxamic acid (AHA) has been proposed for inclusion in advanced, single-cycle, used nuclear fuel reprocessing solvent systems for the reduction and complexation of plutonium and neptunium ions. For this application, a detailed description of the fundamental degradation of AHA in dilute aqueous nitric acid is required. To this end, we present a comprehensive, multiscale computer model for the coupled radiolytic and hydrolytic degradation of AHA in aqueous sodium nitrate and nitric acid solutions. Rate coefficients for the reactions of AHA and hydroxylamine (HA) with the oxidizing nitrate radical were measured for the first time using electron pulse radiolysis and used as inputs for the kinetic model. The computer model results are validated by comparison to experimental data from steady-state gamma ray irradiations, for which the agreement is excellent. The presented model accurately predicts the yields of the major degradation products of AHA: acetic acid, HA, nitrous oxide, and molecular hydrogen.
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Affiliation(s)
- Jacy K Conrad
- Center for Radiation Chemistry Research, Idaho National Laboratory, 1955 N. Fremont Ave., 83415, Idaho Falls, ID, USA
| | - Stephen P Mezyk
- Department of Chemistry and Biochemistry, California State University Long Beach, 1250 Bellflower Blvd, 90840, Long Beach, CA, USA
| | - Liam H Isherwood
- Dalton Cumbrian Facility, The University of Manchester, West Lakes Science Park, CA24 3HA, Moor Row, U. K.,Department of Chemistry, The University of Manchester, Oxford Rd, M13 9PL, Manchester, U.K
| | - Aliaksandr Baidak
- Dalton Cumbrian Facility, The University of Manchester, West Lakes Science Park, CA24 3HA, Moor Row, U. K.,Department of Chemistry, The University of Manchester, Oxford Rd, M13 9PL, Manchester, U.K
| | - Corey D Pilgrim
- Center for Radiation Chemistry Research, Idaho National Laboratory, 1955 N. Fremont Ave., 83415, Idaho Falls, ID, USA
| | - Daniel Whittaker
- National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, CA20 1PG, Cumbria, U.K
| | - Robin M Orr
- National Nuclear Laboratory, Central Laboratory, Sellafield, Seascale, CA20 1PG, Cumbria, U.K
| | - Simon M Pimblott
- Center for Radiation Chemistry Research, Idaho National Laboratory, 1955 N. Fremont Ave., 83415, Idaho Falls, ID, USA
| | - Gregory P Horne
- Center for Radiation Chemistry Research, Idaho National Laboratory, 1955 N. Fremont Ave., 83415, Idaho Falls, ID, USA
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Li C, Yan T, Xiao S, Zheng W. Rate determining step of reduction Np(VI) by organic reagents from 30%TBP/Kerosene to nitrate solution. RADIOCHIM ACTA 2020. [DOI: 10.1515/ract-2020-0028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
A series of single stage trials were conducted using six reducing reagents to investigate the rate determining step during Np(VI) reduction back-extraction from 30%TBP/Kerosene to HNO3 solution under the same conditions. The six reducing reagents included: acetohydroxamic acid, N,N-dimethylhydroxylamine, N,N-diethylhydroxylamine, 2-hydroxyethylhydrazine, methylhydrazine and N,N-dimethylhydrazine. Moreover, the back-extraction of Np(V) from 30%TBP/Kerosene to HNO3 solution without reducing reagent was conducted with the same concentrations of Np and HNO3. The experimental results indicate the rate of Np(VI) reduction in the two-phase system is determined mainly by the rate of Np(V) mass transfer from 30%TBP/Kerosene to HNO3 solution, whose mass transfer kinetics is far slower than previously estimated. The rate determining step is a slow chemical reaction as: NpO2NO3·TBP = NpO2
+ + NO3
− + TBP.
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Affiliation(s)
- Chuanbo Li
- China Institute of Atomic Energy , P.O. Box 275-26 , Beijing, 102413 , China
| | - Taihong Yan
- China Institute of Atomic Energy , P.O. Box 275-26 , Beijing, 102413 , China
| | - Songtao Xiao
- China Institute of Atomic Energy , P.O. Box 275-26 , Beijing, 102413 , China
| | - Weifang Zheng
- China Institute of Atomic Energy , P.O. Box 275-26 , Beijing, 102413 , China
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