INVESTIGATION OF THE REGULARITY OF SYNERGISTIC EXTRACTION Ⅶ.SYNERGISTIC EXTRACTION OF URANYL NITRATE BY THE TERNARY SYSTEM OF AAB SPECIES COMPOSED OF TTA-PMBP-TOPO

The synergistic extraction of uranyl nitrate with binary system of thenoyltrifluoroacetone (TTA) and 1-phenyl-3-methyl-4-benzoyl-pyrazolone (PMBP) with trioctyl phosphine oxide (TOPO) and ternary system of TTA-PMBP-TOPO in chloroform solution are studied.The binary synergistic equilibrium constants are determined to be lgβA1B=3.85(TTA+TOPO system) and lgβA1B=5.29(PMBP + TOPO system) respectively.The purpose of this study is to investigate the ternary synergistic extracting mechanism of AAB species. It is found that synergic effect occured during the extraction of uranyl nitrate with the chloroform solution of TTA+PMBP + TOPO. The formation of a ternary extracted complex UO2(TTA)(PMBP)TOPO is confirmed by the usual slope method. According to the solid angle sum rule, the ternary synergic complex UO2(TTA)(PMBP)TOPO is predicted to be stable. A method proposed by Wang Wenqing3 is used for the calculation of the ternary synergistic equilibrium constant which is evaluated to be lgβA1A2B=4.87.