Calculation of the activity of uranyl nitrate and nitric acid in the H2O–HNO3–UO2(NO3)2–TBP–diluent system using Zdanovskii’s rule

Abstract

The description of the H₂O–HNO₃–UO₂(NO₃)₂–TBP–diluent system required calculation of the activity coefficients of uranyl nitrate and nitric acid in mixed solutions. Three methods for determining the activity coefficients were considered: from the experimental data, using Pitzer’s equation, and using Zdanovskii’s rule with Mikulin’s equations. All the three methods lead to similar results. The relative root-mean-square deviation is 7–10%, but it depends on correct evaluation of the error. The third method will allow calculation of the activity coefficients in multicomponent solutions.