Isotope effects in the V(IV)-malate complex formation system

Abstract

Cation-exchange displacement chromatography of VO 2+ was carried out for studying vanadium isotope fractionation in the malate complex formation system. After the chromatographic elution, the heavier isotope 51V was found to be enriched at the front boundary of the VO 2+ band, which indicates that the heavier isotope is preferentially fractionated into the malate complex in the aqueous solution phase. The isotope separation coefficient ε (= α−1) for 50V and 51V was obtained as 1.0×10 −4 for the malate system at 298 K. This value is smaller than the ones for UO 2 2+ and Cu 2+ in the same ligand systems. Binuclear complex species in UO 2 2+ and Cu 2+ solutions may be attributed to the larger isotope effects in the complex formation system. Through comparison of the reported separation coefficient values of ε per unit mass differences ( ε/Δ M) of the alkali, alkaline earth and transition elements in the complex formation systems, it is suggested that the stronger the complex of the concerned element, the more the isotopic fractionation can obtain.