Solvent extraction chemistry and kinetics of zirconium

Journal Article · Thu May 01 00:00:00 EDT 1980 · Sep. Sci. Technol.; (United States)

DOI:https://doi.org/10.1080/01496398008076280· OSTI ID:6874848

Mailen, J C; Horner, D E; Dorris, S E; Pih, N; Robinson, S M; Yates, R G

The solvent extraction behavior of zirconium in the HNO/sub 3/-tributyl phosphate (TBP) system can be explained based on the existence of four principal aqueous species, Zr/sup 4+/, ZrOH /sup 3+/, Zr/sub 3/(OH)/sub 4/ /sup 8+/, and oxo-polymers. The Zr/sup 4+/ and ZrOH/sup 3+/ species are extractable and are in equilibrium with inextractable Zr/sub 3/(OH)/sub 4/ /sup 8+/. The oxo-polymers are formed by heat, are inextractable, and are not in equilibrium with the other species. The aqueous equilibria and their equilibrium quotients have been previously determined. In the present study, these equilibria were used along with both tracer and macro-zirconium concentrations (oxo-polymers excluded by extraction and back scrubbing) to determine the distribution equilibrium constants for both the Zr /sup 4+/ and ZrOH /sup 3+/ ions. The four equilibrium constants give excellent fits to both tracer and macro-zirconium distribution data. The concentrations of the extractable zirconium species which are calculated from the equilibria have been used to begin examining the extraction kinetics of zirconium in the HNO/sub 3/-TBP system. In relatively concentrated nitric acid, approximately 3 M and greater, Zr/sup 4+/ ion predominates, and the rate of extraction of zirconium increases as approximately the second power of the TBP concentration. In low acid (1 M and less) ZrOH/sup 3+/ ion predominates, and the rate of extraction of zirconium increases as approximately the third power of the nitrate concentration. This is in significant contrast with the behavior of uranium, which shows only a small dependence of the extraction rate on TBP concentration, and no dependence on nitrate concentration. This suggests that operation of a kinetic separations system at low TBP and nitrate concentrations will significantly improve separations over those achieved at equilibrium.

• Research Organization: Oak Ridge National Lab., TN
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 6874848
• Journal Information: Sep. Sci. Technol.; (United States), Vol. 15:4
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ZIRCONIUM
SOLVENT EXTRACTION
CATIONS
CHEMISTRY
NITRIC ACID
POLYMERS
REACTION KINETICS
TBP
ZIRCONIUM COMPLEXES
ZIRCONIUM HYDROXIDES
BUTYL PHOSPHATES
CHARGED PARTICLES
COMPLEXES
ELEMENTS
ESTERS
EXTRACTION
HYDROGEN COMPOUNDS
HYDROXIDES
INORGANIC ACIDS
IONS
KINETICS
METALS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORIC ACID ESTERS
SEPARATION PROCESSES
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
ZIRCONIUM COMPOUNDS
400105* - Separation Procedures