(682d) Uranyl Nitrate Complex Migration Into TBP/Dodecane Organic Solution: A Molecular Dynamics Study

Liquid-liquid extraction of uranyl has been atomistically simulated with the aid of hifidelity quantum chemistry based molecular models. The molecular dynamics simulations of the uranyl-nitrate complex allows us to directly observe the migration of the complexes from the aqueous-organic interface into the TBP/dodecane organic phase. Specifically, the migration of uranyl nitrate complexes from the aqueous-organic interface into the tri-n-butyl phosphate (TBP)/dodecane organic phase, in the form of UO2(NO3)2?H2O?2TBP and UO2(NO3)2?3TBP has been observed. The migration process is characterized by the gradual breaking of all the hydrogen bonds between the complex and the water molecules at the interface. This molecular dynamics simulation study, combined with earlier works by our group [1-2] and experimental evidences [3-6], suggests that the experimentally observed complex UO2(NO3)2?2TBP is formed after the migration of aforementioned complexes into the organic phase by means of a reorganization of the nitrate binding mode from monodentate to bidentate binding which removes the excess oxygen atoms bound to uranyl.

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