摘要
电位法测量了碱金属离子由水相到TBP(磷酸三丁酯)-CH_3OH混合溶剂相的标准迁移自由能⊿G_t^0研究了溶剂化作用同PVC膜对金属离子选择性的关系。碱金属离子的⊿G_t^0随着TBP在混合溶剂中含量的增加而增大。⊿G_t^0还随着离子半径的增大而增大,这同TBP-PVC膜对碱金属离子的选择性次序相一致;而与四苯硼酸盐-TBP-PVC膜对碱金属离子的选择性次序不完全相同。说明了TBP为溶剂的四苯硼酸盐膜对金属离子的选择性除了同溶剂化作用有关外,还同膜相和水相中离子的交换反应常数等因素相关。
The potentiometry with alkali metal ion-responsive glass electrode has been used to obtain the standard molar free energies of transfer, ΔG_t°, of alkali metal chlorides from water to tributylphosphate (TBP)-methanol mixtures at 25℃. The relationship between ion solvation and selectivity of PVC membranes for alkali metal ions has also been studied. As increase of contents of TBP in mixtures, ΔG_t° of alkali metal ions increases, and ΔG_t° rises also with increase of ion radii. This ease is in agreement with sequence of selectivity of TBP-PVC membrane for alkali metal ions, but it is not in aecord with sequence of selectivity of TBP-PVC membrane based on tetraphenylborate. This results shows that the selcetivity of PVC membrane electrodes based on tetraphenylborate is affected by reaction constant of ion exchange between aqueous solution and membrane as well as other factors, besides ion solvation.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
1992年第1期11-15,共5页
Acta Chimica Sinica
基金
国家自然科学基金
