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Quantifying Dimer and Trimer Formation by Tri‑n‑butyl Phosphates in n‑Dodecane: Molecular Dynamics Simulations
Version 2 2016-07-12, 11:19
Version 1 2016-07-11, 13:06
journal contribution
posted on 2016-07-11, 00:00 authored by Quynh
N. Vo, Liem X. Dang, Mikael Nilsson, Hung D. NguyenTri-n-butyl phosphate (TBP), a representative
of neutral organophosphorous ligands, is an important extractant used
in the solvent extraction process for the recovery of uranium and
plutonium from spent nuclear fuel. Microscopic pictures of TBP isomerism
and its behavior in n-dodecane diluent were investigated
utilizing MD simulations with previously optimized force field parameters
for TBP and n-dodecane. Potential mean force (PMF)
calculations on a single TBP molecule show seven probable TBP isomers.
Radial distribution functions (RDFs) of TBP suggest the existence
of TBP trimers at high TBP concentrations in addition to dimers. 2D
PMF calculations were performed to determine the angle and distance
criteria for TBP trimers. The dimerization and trimerization constants
of TBP in n-dodecane were obtained and match our
own experimental values using the FTIR technique. The new insights
into the conformational behaviors of the TBP molecule as a monomer
and as part of an aggregate could greatly aid in the understanding
of the complexation between TBP and metal ions in a solvent extraction
system.