Calculation of the equilibrium in the extraction of nitric acid with 30 and 12% Tri-n-butylphosphate solutions in dodecane

The concentrations of nitric acid and tri- n -butylphosphate (TBP) have been calculated for 30 and 12% TBP solutions in dodecane from the experimental data for the H 2 O-HNO 3 -TBP–dodecane system. The used model implies the formation of the HNO 3 · TBP monosolvate, the HNO 3 · 2TBP disolvate, and the 2HNO 3 · TBP semisolvate. The mean-square relative deviations of the calculated data from experimental results have been determined and used to optimize the calculated formation constants of the solvates and their hydrate numbers. The calculated 2HNO 3 · TBP semisolvate concentrations in the studied data array are small and can be neglected. It has been established that the extraction of nitric acid with 30 and 12% TBP solutions in dodecane can be described by the same equation.