Contribution of extraction isotherms modeling based on the Mikulin–Sergievskii–Dannus approach to the speciation of plutonium(IV) in TBP 30 %/dodecane

Abstract

Abstract In this study, a thermodynamic model based on Mikulin and Sergievskii–Dannus equations to calculate activity coefficients in both organic and aqueous phases was used to model plutonium(IV), nitric acid and water extraction by 30% TBP in dodecane. The speciation of Pu(IV) in the organic phase was determined via extraction isotherms modeling. The best agreement between experimental and calculated plutonium distribution ratios was obtained by considering two Pu(IV) complexes in the organic phase: Pu(NO3)4(TBP)2 and Pu(NO3)4(TBP)3.