Empirical modeling of distribution coefficient of Zr(IV) in nitric acid - tributyl phosphate/normal paraffin hydrocarbon

In the extraction cycles of Purex process of nuclear fuel reprocessing zirconium is of particular importance because it is one of the most readily extractable of longer-lived fission products, and therefore one frequently contaminates uranium or plutonium product solutions. Theoretical and experimental studies have been initiated to find out a suitable distribution coefficient co-relation of Zr(IV). The present paper describes calculations of distribution coefficient of Zr(IV) between aqueous nitrate solutions and 30 vol% TBP/NPH. The correlation functions are described as a mathematical model in which equilibrium constants are expressed as a function of total nitrate salting strength by a quadratic polynomial. A generalized least-squares techniques has been used to determine equilibrium constants of Zr(IV) and its variation with the medium composition in solvent extraction equilibria by minimizing the difference between observed and calculated distribution coefficients using experimental data. The results presented here shall be useful for the flowsheet simulation of extraction cycles of Purex process