MODELING OF NITRIC-ACID AND WATER EXTRACTION FROM AQUEOUS-SOLUTIONS CONTAINING A SALTING-OUT AGENT BY TRI-N-BUTYLPHOSPHATE

A thermodynamic model is presented for nitric acid and water extractio n equilibria by tri-n-butylphosphate (10, 30, 50 and 100 vol%) in dode cane from aqueous solutions containing nitric acid (0-14M) and in pres ence or not of a salting-out agent (lithium nitrate, ammonium nitrate) . The activity coefficient of nitric acid was calculated from experime ntal data using MIKULIN's equation, and those of the components in the organic phase were calculated by SERGIEVSKII-DANNUS' equation. A sati sfactory description of the distribution of nitric acid and water is o btained in a wide range of acidity of the aqueous phase by taking into account the formation of the following complexes: TBP, TBP H2O,HNO3 . H2O, TBP . HNO3, (TBP)(2) . HNO3 . H2O, TBP . (HNO3)(2).