Water and Mean Ionic Activities of Aqueous HNO₃ Solutions Calculated from an Extension of the Brunauer-Emmett-Teller (BET) Model

Abstract

The objective for this research was to employ the extended adsorption isotherm (EAI) to develop a predictive relationship between the activity of H₂O (a_w) and the mean ionic activity (a_±) of aqueous HNO₃. The EAI model is a calculative approach to the estimation of solutions for activities of highly non-ideal chemical systems and is the collective efforts of Stokes and Robinson, Abraham, and Ally and Braunstein. From previous works of the HNO₃-H₂O system by Rains et al., a predictive model of relevant aqueous phase activities was developed that only needs knowledge of composition and temperature of the HNO₃ solution.

Keywords:

• activity coefficient
• aqueous electrolyte
• Brunauer-Emmett-Teller (BET)
• mean ionic activity
• modified adsorption isotherm (MAI)
• nitric acid
• Stokes-Robinson
• water

ACKNOWLEDGEMENTS

This work was supported by the US Department of Energy by contract DE-FC07-06ID14735, the Aid to Education Program of E. I. du Pont de Nemours and Company and Oak Ridge National Laboratory (ORNL); ORNL is managed and operated by UT-Battelle, LCC under DOE Contract No. DE-AC05-000R22725 with ORNL.