FT-IR SPECTROSCOPY OF NITRIC ACID IN TBP/OCTANE SOLUTION^*

Abstract

Infrared studies for the HNO₃/0.73 M TBP n-octane system are reported. Two extracted species, TBP · HNO₃ and TBP · 2HNO₃, were identified in the organic phase. The concentration of the individual species was determined by the analysis of the vibrational band at ∼1650 cm⁻¹. The band at 1648 cm⁻¹ was assigned to the monosolvate TBP · HNO₃ and the band at 1672 cm⁻¹ to the hemisolvate TBP · 2HNO₃. The infrared spectra revealed that with respect to the P═O bond, as well to each other, the HNO₃ molecules in the hemisolvate are spectrally non-equivalent. The predominant structure of TBP · 2HNO₃ involves the chain HNO₃ dimer. Some ionic NO₃ ⁻ and hydronium ions were identified in this system but only during formation of the monosolvate. The analyses performed in this system can serve for the characterization of HNO₃ in related systems in the presence of metal species.

^*Work performed under the auspices of the office of Basic Energy Sciences, Division of Chemical Sciences, Department of Energy, under contract W-31-109-ENG-38.

Keywords:

• Infrared spectra
• TBP
• Nitric acid
• Third phase

ACKNOWLEDGMENTS

This work was funded by the Office of Basic Energy Sciences, Division of Chemical Sciences, U.S. Department of Energy, under contract W-31-109-ENG-38.

The authors thank P.G. Rickert of ANL for the purification of the TBP batch used in this work.

Notes

^*Work performed under the auspices of the office of Basic Energy Sciences, Division of Chemical Sciences, Department of Energy, under contract W-31-109-ENG-38.