多醚萃取体系中锂的同位素效应——盐浓效应  

LITHIUM ISOTOPE EFFECT IN THE EXTRACTION SYSTEMS OF POLYETHERS——EFFECT OF SALT CONCENTRATION

作　　者：方胜强[1] 傅立安[1] 

机构地区：[1]兰州大学现代物理系

出　　处：《同位素》1991年第3期166-173,共8页Journal of Isotopes

摘　　要：测定了苯並-15-冠-5的氯仿溶液在20℃下萃取浓度大于2mol/l LiBr时的锂同位素分离系数α,确证α随LiBr浓度增加而增大。结合文献数据判定盐浓效应的本质在于Kp(盐浓>2mol/l时)和K_Q(盐浓<1—2mol/l时。即LiI<1.0mol/l,LiBr<1.5mol/l;LiCl<2.0mol/l)的作用。K_P和K_Q分别为水相锂盐缔合离子对与水合锂离子之间以及锂盐的冠醚络合物与水合锂离子之间的锂同位素交换平衡常数。Separation factors of lithium isotopes at 20℃ were determined in the extraction systems of B15C5-CHCl_3/LiBr-H_2O, The initial concentration of LiBr was controlled in the extent of more than 2mol/1. It may be established that the increase of LiBr concentration causes a remarkable increase of the separation factor. The essence of this effect due to the change in salt concentration was discussed in connection with examination of relevant phenomena in literature,, It can be concluded that the relationship between a and Cm, the concentration of lithium salt, is dependent on K_Q and K_P, where K_Q and K_P express lithium isotope exchange equilibrium constants between Li-crownether complex and hydrated lithium ion for lithium concentration less than 1—2 mol/1, and that between lithium salt ion pair and hydrated lithium ion for lithium concentration more than 2mol/1 in aqueous phase respectively.

关 键 词：冠醚 锂 溶剂萃取 同位素效应 

分 类 号：O614.111[理学—无机化学]