Kinetics of Np(VI) reduction with carbohydrazide in nitric acid

Zavalina, O. A.; Dvoeglazov, K. N.; Pavlyukevich, E. Yu.; Stepanov, S. I.

doi:10.1134/s1066362217050034

Cited by 4 publications

(4 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It has been suggested to remove Np from the SNF reprocessing process using advanced PUREX processes such as the Partitioning Conundrum Key (PARC) process and SUPERPUREX process . Some free-salt reductants such as hydroxyurea, , hydrazine, − and their derivatives have been experimentally applied to reduce Np(VI).…”

Section: Introductionmentioning

confidence: 99%

“…Yan and his co-workers also studied the reduction reaction of Np(VI) and Np(V) by dihydroxyurea (DHU) using spectrophotometry and found that DHU can quite rapidly reduce Np(VI) to Np(V), while it very slowly reduces Np(V) to Np(IV) . Koltunov et al reported the kinetic and mechanistic studies on the reduction of Np(VI) by hydrazine and its derivatives, which directly reduces Np(VI) to Np(V) without further reduction to Np(IV) under suitably controlled conditions. ,, Recently, carbohydrazide (CO(N 2 H 3 ) 2 ), a derivative of hydrazine and urea, has received much attention because it can solely reduce Np(VI) to Np(V) in the extraction reprocessing of high-burn-up spent nuclear fuel. ,,− Volk et al reported that carbohydrazide can quickly reduce Np(VI) to Np(V), while it further reduces Np(V) to Np(IV) very slowly . Zavalina et al studied the reduction kinetics of Np(VI) by carbohydrazide in nitric acid solution and found that the reduction rate increases with increasing concentration of reductant and temperature .…”

Section: Introductionmentioning

confidence: 99%

“…Koltunov et al reported the kinetic and mechanistic studies on the reduction of Np(VI) by hydrazine and its derivatives, which directly reduces Np(VI) to Np(V) without further reduction to Np(IV) under suitably controlled conditions. ,, Recently, carbohydrazide (CO(N 2 H 3 ) 2 ), a derivative of hydrazine and urea, has received much attention because it can solely reduce Np(VI) to Np(V) in the extraction reprocessing of high-burn-up spent nuclear fuel. ,,− Volk et al reported that carbohydrazide can quickly reduce Np(VI) to Np(V), while it further reduces Np(V) to Np(IV) very slowly . Zavalina et al studied the reduction kinetics of Np(VI) by carbohydrazide in nitric acid solution and found that the reduction rate increases with increasing concentration of reductant and temperature . Subsequently, Shilov et al further studied the reduction mechanisms of Np(VI) by carbohydrazide in perchloric acid solution and obtained activation energy with 86 ± 5 kJ mol –1 .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Insights into the Reduction Mechanisms of Np(VI) to Np(V) by Carbohydrazide

Wang

et al. 2023

J. Phys. Chem. A

View full text Add to dashboard Cite

An efficient approach to Np separation in the Plutonium Uranium Reduction EXtraction (PUREX) process is to adjust Np(VI) to Np(V) by free-salt reductants, such as hydrazine and its derivatives. Recently, carbohydrazide (CO(N 2 H 3 ) 2 ), a derivative of hydrazine and urea, has received much attention, which can reduce Np(VI) to Np(V) in the extraction reprocessing of spent nuclear fuel. Herein, according to the experimental observations, we examine the reduction mechanism of four Np(VI) by one carbohydrazide molecule using multiple theoretical calculations. The fourth Np(VI) reduction with a 22.26 kcal mol −1 energy barrier is the rate-determining step, which is in accordance with the experimental observations (20.54 ± 1.20 kcal mol −1 ). The results of spin density reflect that the reduction of the first and third Np(VI) ion is an outer-sphere electron transfer, while that of the second and fourth Np(VI) ion is the hydrogen transfer. Localized molecular orbitals (LMOs) uncover that the breaking of the N−H bond and formation of the O yl −H bond are accompanied by the reaction from initial complexes (ICs) to intermediates (INTs). This work offers basic perspectives for the reduction mechanism of Np(VI) to Np(V) by CO(N 2 H 3 ) 2 , which is also expected to design excellent free-salt Np(VI) reductants for the separation of Np in the advanced PUREX process.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Insights into the Reduction Mechanisms of Np(VI) to Np(V) by Carbohydrazide

Wang

et al. 2023

J. Phys. Chem. A

View full text Add to dashboard Cite

show abstract

“…Therefore, the more efficient separation of Np from U and Pu in the PUREX process is the reduction of Np(VI) to Np(V). Experimental results have been reported for several highly efficient and environment-friendly Np(VI) reductants, including oximes, [4][5][6] aldehydes, [7][8][9] hydroxylamine, [10][11][12][13][14] urea, 15,16 hydroxamic acid, [17][18][19][20] hydrazine, [21][22][23][24][25][26][27][28] and their derivatives. Acetaldoxime reduces Np(VI) to Np(V) only at less than 2 M nitric acid concentration and low temperature (308 K).…”

Section: Introductionmentioning

confidence: 99%