FT-IR study of third phase formation in the U(VI) or Th(IV)HNO{sub 3}, TBP/alkane systems.

Journal Article · Tue Jan 01 04:00:00 EST 2002 · Solvent Extr. Ion Exch.

DOI:https://doi.org/10.1081/SEI-120004807· OSTI ID:949477

Borkowski, M; Ferraro, J R; Chiarizia, R; McAlister, D R

The infrared reflectance spectra of the third phases formed in the systems UO{sub 2}(NO{sub 3}){sub 2}/HNO{sub 3}/20%TBP in n-dodecane and Th(NO{sub 3}){sub 4}/HNO{sub 3}/20%TBP in n-octane gave evidence for the presence in solution of a significant amount of weakly bonded molecular nitric acid. From the correlation between the ratio of the areas of the bands at 1672 cm-1 and 1648 cm-1, characteristic of weakly intermolecularly hydrogen-bonded nitric acid and nitric acid strongly bonded to TBP, respectively, the molecular HNO{sub 3} concentration was determined. The presence of these two bands in the spectra of the third phase samples provides evidence that only part of the HNO{sub 3} is directly and strongly bound to the TBP phosphoryl group. The ratio of the weakly intermolecularly hydrogen-bonded HNO3 to that bound directly to P=O group of TBP was much higher for the uranium than for the thorium third phases formed under comparable conditions. The estimated amounts of the weakly intermolecularly hydrogen-bonded HNO{sub 3} were about 47% and 30% of the total HNO{sub 3} present in the uranium and thorium systems, respectively. In the uranium third phase, the TBP hemisolvate of HNO{sub 3} (TBP{dot c}2HNO{sub 3}) was recognized as the predominant species with accompanying very small amount of monosolvate (TBP{dot c}HNO{sub 3}). In the thorium system the hemisolvate of HNO{sub 3} was also present, but the monosolvate was found to be the major species. When the thorium concentration in the third phase was increased, a conversion of monosolvate into hemisolvate was observed. Analysis of the infrared spectra for both systems indicated that the nitrate anions form bidentate chelates with the studied metals.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 949477
• Report Number(s): ANL/CHM/JA-41366
• Journal Information: Solvent Extr. Ion Exch., Journal Name: Solvent Extr. Ion Exch. Journal Issue: 3 ; 2002 Vol. 20; ISSN 0736-6299; ISSN SEIEDB
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ALKANES
ANIONS
CHELATES
INFRARED SPECTRA
NITRATES
NITRIC ACID
SPECTRA
THORIUM
URANIUM