Comparison of ReO₄ ⁻ and TcO₄ ⁻ in solvent extraction systems

Abstract

Abstract The suitability of perrhenate (Re(VII)) to act as an analog for pertechnetate (Tc(VII)) was tested using solvent extraction and the carrier/tracer systems 99 Tc(VII)/ 99m Tc(VII) and 185/187 Re/ 186/188 Re(VII). Perrhenate is often used as a non-radioactive analogue of pertechnetate, but scarce data is available for the comparison of these metals for liquid-liquid extraction applications. Results show that neither Tc(VII) nor Re(VII) extraction is influenced by pH in the 2–8 range. The anion extractant also separates electrolyte anions, with increasing extraction following the order Cl − < NO 3 − ≪ ClO 4 − , resulting in a decreased Tc(VII) and Re(VII) extraction in presence of salt. In particular, the extraction of Re and Tc is suppressed in presence of NaCl at concentrations higher than 1 mM. While Tc extraction is larger than that of Re in absence of electrolyte, they are statistically identical in presence of enough electrolyte. Furthermore, tetraphenylphosphonium chloride (Ph 4 PCl) is a stronger extractant than iodonitrotetrazolium chloride (INT).