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Title: Quantifying Dimer and Trimer Formation by Tri- n -butyl Phosphates in n -Dodecane: Molecular Dynamics Simulations

Tri-n-butyl phosphate (TBP), a representative of neutral organophosphorous ligands, is an important extractant used in 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 (RDF) of TBP suggests 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 FTIR technique. The new insights into the conformational behaviors of TBP molecule as a monomer and as part of an aggregate could greatly aid the understanding of the complexation between TBP and metal ions in solvent extraction system. The U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences funded the work performed by LXD.
Authors:
; ; ;
Publication Date:
OSTI Identifier:
1322512
Report Number(s):
PNNL-SA-116920
Journal ID: ISSN 1520-6106; KC0301050
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry; Journal Volume: 120; Journal Issue: 28
Publisher:
American Chemical Society
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
Tri-n-butyl Phosphate; solvent extraction; molecular dynamics simulations; reverse micelles; self-association; equilibrium constants