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ABSTRACT
A liquid membrane system to enrich zinc isotope was investigated. The liquid membrane was composed of a solution of dicyclohexano-18-crown-6 in chloroform. Zinc chloride dissolved in diluted hydrochloric acid was used as a feed phase. A receiving phase was made of a 0.001 M HCl solution. The zinc isotopes were enriched (1) at the interface of the Iiquid-membrane/feed-phase and (2) at that of the liquid-membrane/receiving-phase. The separation factor attained in the system was α = 1.049 for the separation of 64Zn and 66Zn. The enrichment factor of 66Zn relative to 67Zn was â â 0.053, which is in the inverse direction of enrichment by a liquid-liquid extraction. The enrichment factor of 64Zn to 66Zn showed a different value from that of 66Zn to 68Zn, regardless of their similar mass difference. The isotope effects in the Zn-crown complex were dominated by the field shift of electronic energy in the isotope atom. This is in contrast to the Bigeleisen-Mayer approximation for a chemical exchange reaction.