Ion exchange characteristics of palladium and ruthenium from a simulated radioactive liquid waste

Radioactive high-level liquid wastes contain significant quantities of platinum group metals (PGM), such as palladium [Pd(II)], rhodium [Rh(III)], and ruthenium [Ru(III)]. The PGM are produced as fission products in nuclear reactors. In this study, batch and column experiments were carried out to investigate the ion exchange characteristics of Pd(II) and Ru(III), including the effects of the ionic group of ion exchangers, solution temperature, and the concentration of nitric acid by various anion exchangers such as IRN 78 and Dowex 1x8. The elution characteristics of Pd(II) and Ru(III) by various eluents were also investigated. The rate of ion exchange of Pd(II) and Ru(III) by an anion exchanger was very rapid and reached an equilibrium state within 1 hour. Anion exchangers such as Dowex 1x8 with the ionic group of quaternary methyl ammonium had a higher capacity than anion exchanger, such as IRN 78 with amine group, for the adsorption of Pd(II) and Ru(III). Pd(II) could be easily eluted by 0.5 M thiourea solution and 0.1-M nitric acid mixed solution. Ru(III) was effectively eluted by a 6-M HCl solution.