Separation and recovery of palladium from nitric acid solution by silica based benzo-15-crown-5 ether resin

The Aprés ORIENT research program, as a newly concept of advanced nuclear fuel cycle, was initiated in FY2011 aiming at creating stable, highly-valuable elements by nuclear transmutation from fission products (FPs). As creation of palladium (Pd) from rhodium (Rh) in FPs is one of the most important targets of the program, the research and development of highly effective separation methods between Rh and Pd are strongly required. In the present paper, an ability of silica based benzo-15-crown-5 ether (B15C5) resin for adsorption and elution of Ru(III), Rh(II), and Pd(II) was investigated in nitric acid (HNO3) solution. As a result of the batch experiment for adsorption, Pd(II) were strongly adsorbed by B15C5 resin in HNO3. On the other hand, Ru(III) and Rh(III) were not adsorbed by the resin. As it was difficult to elute adsorbed Pd(II) by the change of the concentration of HNO3, ethylenediamine (EDA) was employed as an eluent for Pd(II). As a result of the column chromatography for adsorption and elution, only Ru(III) and Rh(III) were eluted in 2 mol/L of HNO3, and then Pd(II) was clearly eluted in a mixed solution including 2 mol/L of HNO3 and 2 mol/L of EDA. Therefore, by using EDA as the eluent, the possibility of B15C5 resin for separation and recovery of Pd created by transmutation of Rh in FPs has been found.