Molecular interactions in tri-n-butyl phosphate-diluent mixtures

Journal Article · Sat Jun 01 04:00:00 EDT 1996 · Industrial and Engineering Chemistry Research

DOI:https://doi.org/10.1021/ie950626b· OSTI ID:256866

Choi, K; Tedder, D W ^[1]

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1. Georgia Inst. of Technology, Atlanta, GA (United States). School of Chemical Engineering

This model considers both specific chemical and nonspecific physical contributions to excess Gibbs energy. Competitive chemical equilibria are evaluated to describe specific chemical interactions. Molecular size, shape difference, and regulation solution terms, based on the ``true`` species, are used to describe nonspecific physical interactions. Parameter estimates are obtained by fitting vapor-liquid equilibrium and hydrogen and phosphorus NMR shift data for three tri-n-butyl phosphate (TBP) and diluent binary mixtures. The thermodynamic equilibrium constant for the TBP dimer is a shared parameter since this complex apparently exists in all binary mixtures. At 22 C, its value is 6.65 based on the behavior of TBP diluted with either benzene, chloroform, or n-heptane. Thermodynamic equilibrium constants for the 1:1 TBP/chloroform and TBP/benzene complexes are 37.88 and 1.34, respectively. The 1:2 chloroform/TBP dimer complex has an equilibrium constant of 37.57. Model parameters are used to predict excess molar volumes and enthalpies. Commonly reported stability constants are shown to be concentration dependent. TBP has been widely used in the processing of heavy-metal ores and spent fuel elements. It is often mixed with a diluent to improve solvent properties (e.g., to reduce viscosity or to control its extraction power).

• OSTI ID: 256866
• Journal Information: Industrial and Engineering Chemistry Research, Journal Name: Industrial and Engineering Chemistry Research Journal Issue: 6 Vol. 35; ISSN 0888-5885; ISSN IECRED
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
DILUTION
DIMERIZATION
MOLECULAR MODELS
REPROCESSING
SOLVENT EXTRACTION
SPENT FUELS
TBP
THERMODYNAMIC PROPERTIES