Molecular dynamics simulations of uranyl and plutonyl cations in a task-specific ionic liquid

Katie A Maerzke ^1,2, George S Goff ², Wolfgang H Runde ²

⁰Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA.

The Journal of Chemical Physics +

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October 15, 2024

View abstract on PubMed

Summary

Task-specific ionic liquids (TSILs) like [Hbet][Tf2N] enhance actinide separations in nuclear waste management. Betaine ligands strongly coordinate actinides, forming stable dimeric complexes and reducing cation diffusion in IL/water mixtures.

Area Of Science

Nuclear Chemistry and Engineering
Materials Science
Computational Chemistry

Background

Ionic liquids (ILs) offer tunable properties for nuclear separations.
Task-specific ionic liquids (TSILs) improve metal solubility in ILs.
Water impurity in ILs can affect actinide coordination and separation efficiency.

Purpose Of The Study

To investigate the coordination and dynamics of uranyl(VI) and plutonyl(VI) in IL/water mixtures.
To understand the role of betaine (Hbet) as a ligand for actinyl cations.
To elucidate the molecular-level behavior of actinides in TSIL/water systems for improved separations.

Main Methods

Classical molecular dynamics (MD) simulations.
Potential of Mean Force (PMF) simulations.
Analysis of actinyl cation coordination, dynamics, and complex formation.

Main Results

Betaine is a strong, bidentate ligand for actinyl cations, preferred over water.
Betaine coordination reduces actinyl cation diffusion coefficients.
Stable dimeric actinyl complexes form, with betaine bridging metal centers.

Conclusions

TSILs with functionalized ligands like betaine are effective for actinide complexation.
Understanding ligand-metal interactions at the molecular level is crucial for designing separation processes.
Simulated dimeric structures are consistent with experimental crystallographic data.