Interfacial Complex Formation in Uranyl Extraction by Tributyl-Phosphate in Dodecane Diluent: A Molecular Dynamics Study
- ORNL
Atomistic simulations have been carried out in a multicomponent two-phase system (aqueous and organic phases in direct contact) to investigate the interfacial molecular mechanisms leading to uranyl extractionfrom the aqueous to organic phase. The aqueous phase consists of the dissolved ions UO2^2+ and nitrate NO3-,with or without H3O+, in water to describe acidic or neutral condition; the organic phase consists of tributyl phosphate, the extractant, in dodecane as the diluent. We find that the interface facilitates the formation of various uranyl complexes, with a general formula UO2^2+(NO3-)n mTBP kH2O, with n + m + k ) 5, suggesting a 5-fold coordination. The coordination for all three molecular entities has the common feature that they all bind to the uranyl at the uranium atom with an oxygen atom in the equatorial plane perpendicular to the molecular axis of the uranyl, forming a 5-fold symmetry plane. Nitric acid has a strong effect in enhancing the formation of extractable species, which is consistent with experimental findings.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Laboratory Directed Research and Development (LDRD) Program
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 973121
- Journal Information:
- Journal of Physical Chemistry, Vol. 113, Issue 29; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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