In a heterogeneous electrolyte system of a strongly basic anion exchanger and solutions of NaBF4 or NaClCO4 we established the influence of the nature and concentration of the eluent in chromatographic experiments on chlorine isotope separation. Results show that when the electrolyte concentration is increased the degree of isotope separation decreases. With NaBF4 the separation factor is greater than with NaClO4 under conditions which are otherwise the same. For electrolyte solutions containing ClO4-, NO3- and BF4- there is a linear relation between the separation factor of the chlorine isotopes and the logarithm of the heat of anion hydration of the elution electrolyte.
Im heterogenen Elektrolytsystem stark basischer Anionenaustauscher/konzentrierte Fluoridlösung wird die Abhängigkeit der Chlorisotopenseparation von Konzentration und Gegenion des Fremdelektrolyten in chromatographischen Versuchen bestimmt. Die Ergebnisse zeigen den bisher größten bekannten Elementartrenneffekt der Chlorisotope bei Ionenaustauschreaktionen, wobei sich das 37Cl− ‐ gegenüber dem 35Cl−‐Ion in der Lösung des Systems anreichert. Mit steigender Fluoridkonzentration nimmt der Isotopentrenneffekt ab. Am Beispiel einer CsF ‐ gegenüber einer KF ‐ Lösung wird die starke Abhängigkeit der Isotopenseparation vom Gegenion des Fremdelektrolyten aufgezeigt.
AbstractHydrous zirconium dioxide is used in column experiments for separating the halide ions as well as for isotope fractionation of chlorine. The preparation of the zirconium dioxide particles is carried out by homogeneous hydrolysis of a zirconyl chloride solution using hexamethylenetetramine. The separation order of the halides is I-, Br- and Cl- in contrast to the inverse separation order using a strongly basic anion exchange resin. In chlorine isotope separation experiments an enrichment of 35Cl- is found in the first fractions, whereas the last fractions show a significant enrichment of 37C1-. This also indicates an inversion of the isotope separation compared with a strongly basic anion exchange resin. A dependence of the isotope fractionation on the concentration of the NaNO3 solution used as eluant is found. With increasing concentration the isotope fractionation decreases. Using a 0.5 M NaNO3 solution the elementary separation effect was calculated e = 6,1 · 10-4 . This is one of the highest isotope fractionations known in a chloride isotope exchange system. The results show that the electrolyte behaviour of isotopes is comparable to that of a series of homologous elements.
Untersuchungen mit dem stark basischen Anionenaustauscher AGl ‐XlO und Lösungen von NaBF4 oder NaClO4 zeigen, daß steigende Elektrolytkonzentration einen sinkenden Isotopentrennungsgrad zur Folge hat.
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