Multi-scale modelling of uranyl chloride solutions

Area of Science:

• Chemistry
• Physical Chemistry
• Computational Chemistry

Background:

• Uranyl chloride (UO2Cl2) solutions are crucial in nuclear fuel reprocessing and waste management.
• Understanding uranyl-chloride interactions and hydration is essential for predicting solution behavior.

Purpose of the Study:

• To determine the structural and thermodynamic properties of binary aqueous uranyl chloride solutions.
• To investigate hydration properties and ion-ion interactions in concentrated uranyl chloride solutions.
• To calculate uranyl-chloride association constants using a multi-scale approach.

Main Methods:

• Classical molecular dynamics simulations with explicit polarization.
• Calculation of McMillan-Mayer potentials for ion-ion interactions.
• Multi-scale approach combining simulation and theoretical potentials for association constant calculation.

Main Results:

• Simulations accurately reproduced experimental bond distances and coordination numbers for hydrated uranyl.
• Two stable chloride positions were identified in the second hydration shell of uranyl.
• Calculated uranyl-chloride association constant (KUO2Cl+) agreed well with experimental values (1.48 L mol(-1)).

Conclusions:

• Molecular dynamics simulations are effective for studying uranyl chloride aqueous solutions.
• The study provides insights into uranyl hydration and ion-pair interactions.
• While association constants are accurate, activity coefficients require further refinement at higher concentrations.