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Prediction of Redox Potentials for U, Np, Pu, and Am in Aqueous Solution

Journal Article · · Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory
 [1];  [2];  [2];  [2];  [2]
  1. Universidade Estadual de Campinas, São Paulo (Brazil); University of Alabama, Tuscaloosa, AL (United States)
  2. University of Alabama, Tuscaloosa, AL (United States)

The redox properties of the actinides in aqueous solution are important for fuel production/reprocessing and understanding the environmental impact of nuclear waste. The redox potentials for U, Np, Pu, and Am in oxidation states from 0 up to VII (as appropriate) in aqueous solutions have been predicted at the density functional theory level with the B3LYP functional, Stuttgart small core pseudopotential basis sets for the actinides, and explicit (30H2O molecules)/implicit treatment of the aqueous solvent using the self-consistent reaction field COSMO and SMD approaches for the implicit solvation. The predictions of the structural parameters of clusters incorporating first and second solvation shells are consistent with the available experimental data., Our results are typically within 0.2 V of the available experimental data using two explicit solvation shells with an implicit solvent model. The use of the PW91 functional substantially improved the prediction of the Pu(VI/V) redox couple. The redox couples for An(VI/IV) and An(V/IV) which involve the addition of protons and removal of the actinyl oxygens led to slightly larger differences from experiment. Here, the An(IV/0) and An(III/0) couples were reliably predicted with our approach. Predictions of the unknown An(II/I) redox potentials were negative, consistent with expectations, and predictions for unknown An(VII/VI), An(III/II), and An(II/0) redox couples improve prior estimates.

Research Organization:
University of Alabama, Tuscaloosa, AL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES); São Paulo Research Foundation (FAPESP)
Grant/Contract Number:
SC0018921
OSTI ID:
3004800
Alternate ID(s):
OSTI ID: 2577450
Journal Information:
Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory, Journal Name: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory Journal Issue: 28 Vol. 128; ISSN 1089-5639; ISSN 1520-5215
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English

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  • Marenich, Aleksandr V.; Cramer, Christopher J.; Truhlar, Donald G.
  • The Journal of Physical Chemistry B, Vol. 113, Issue 18, p. 6378-6396 https://doi.org/10.1021/jp810292n
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