Calcium Hydroxide Isotope Effect in Calcium Isotope Enrichment by Ion Exchange

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Abstract
The enrichment of calcium isotopes has been observed in ion-exchange chroma-tography with an aqueous phase of calcium hydroxide and a solid phase of sulfonic acid resin. The band front was exceedingly sharp as a result of the acid-base reaction occurring at the front of the band. Single-stage separation coefficients were found to be ε(44Ca/40Ca) = 11 × 10−4 and ε(48Ca/40Ca) = 18 × 10−4. The maximum column separation factors achieved were 1.05 for calcium-44 and 1.09 for calcium-48 with the heavy isotopes enriching in the fluid phase. The calcium isotope effect between fully hydrated aqueous calcium ions and undissociated aqueous calcium hydroxide was estimated. For the calcium-44/40 isotope pair the separation coefficient was 13 × 10−4.