Phase diagrams of the ternary liquid systems [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2] and [Ce(NO3)3(TBP)3]-C10H22-[Th(NO3)4(TBP)2] and of the quaternary liquid system [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2]-[Th(NO3)4(TBP)2

Abstract

The phase diagrams of the ternary liquid systems [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2] and [Ce(NO3)3(TBP)3]-C10H22-[Th(NO3)4(TBP)2] and of the quaternary liquid system [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2(TBP)2]-[Th(NO3)4(TBP)2] at T = 298.15 K are constructed. The phase diagrams are characterized by areas of homogeneous solutions and of two-phase liquid systems (systems with phase separation), with one phase (I) enriched in [Ce(NO3)3(TBP)3], [Th(NO3)4(TBP)2], and [UO2(NO3)2(TBP)2], and the other phase (II), in C10H22. Using the data on the mutual solubility of the components in the systems under consideration and equations of the NRTL model, the parameters of intermolecular interactions and the excess Gibbs energies (Gex) were calculated for the binary, ternary, and quaternary systems. Passing from the ternary system [Ce(NO3)3(TBP)3]-C10H22-[Th(NO3)4(TBP)2] to the quaternary system [Ce(NO3)3(TBP)3]-C10H22-[UO2(NO3)2 (TBP)2]-[Th(NO3)4(TBP)2] does not appreciably affect the distribution of C10H22 between phases I and II, but leads to the redistribution of [Ce(NO3)3(TBP)3] into phase II and of [Th(NO3)4(TBP)2] into phase I.