イオン交換体による同位元素分離に関する基礎的知見,(IV)

Abstract

The ion exchange separation factors of lithium isotopes in LiCl and LiOH solutions were determined with differently cross-linked sulfonated styrene-divinylbenzene copolymers and a synthetic inorganic ion exchanger, lonite C, (Zirconium phosphate type).The isotopic ratios of lithium were measured by Atlas CH 4 mass-spectrometer using thermionic method.(1) The highest separation factor, 1.022, was obtained for the system of 0.1M LiOH in 20% acetone-H2O mixture using lonite C.(2) LiOH system gave higher separation factors than LiCl system. From experimental data, the equilibrium constant of the following isotope exchange reaction in solution was estimated tentatively as 1.04.7Li++6LiOH_??_6Li++7LiOH(3) Synthetic inorganic ion exchanger, lonite C, gave higher separation factors than the organic ones. This fact can be explained by the following isotope exchange reaction in the exchanger phase:(7Li)E+E6Li_??_(6Li)E+E7Liand its equilibrium constant was estimated as 0.992.(4) The highly cross-linked ion exchange resins and the addition of ethanol or acetone were also effective to obtain the higher separation factors.