关键词: 系数, 同位素标记, 磷酸三丁酯, 活度, 蒸气压力, 水相, 磷同位素

The activity coefficients of TBP in various diluents (C6H6, CHCl3, CCl4, and PhCl) were determine by 32P-labeled TBP distribution and vapor pressure measurements. By assuming that the activity coefficients of TBP in H2O is 1, the solvent activity coefficients g1 measured by 2 different methods show some discrepancies. Comparison of the activity coefficients of 4 systems determine by the 2 methods showed the regularity of TBP activity coefficient in the aqueous phase. The g'2/g'20 value and the equation g2 = (g'2/g'20A2/x2) are used to calculate g2, where g1 denotes activity coefficient of TBP in the organic solvent, g2, activity coefficient of TBP solution in the aqueous phase; g'20, activity coefficient of pure TBP in the aqueous phase; x2, mol fraction of TBP in the organic phase; A2, the ratio of radioactivities of aqueous phase equilibrated with 32P-labeled TBP solution and pure TBP. The activity coefficient g1 was calculated with the Gibbs-Duhem equation.

Key words: COEFFICIENTS, ISOTOPE LABELLING, PHOSPHORIC ACID TRIBUTYL ESTER, ACTIVITY, VAPOR PRESSURE, WATER PHASE, PHOSPHORUS ISOTOPES