Radiation stability of two extraction chromatography resin materials containing substituted diglycolamide ligands in an ionic liquid

The radiation stability of two extraction chromatography resins containing diglycolamide ligands viz. TPDGA (N,N,N',N'-tetra-n-pentyl diglycolamide) and TODGA (N,N,N',N'-tetra-n-octyl diglycolamide) in a room temperature ionic liquid (C4mim.NTf2) was studied by exposing to gamma rays from a 60Co source. The resins were irradiated to varying gamma ray dose up to 1000 kGy where both the dry resins and wet resins (containing a fixed amount nitric acid in contact) were used. The performance assessment of the resins was done by physicochemical characterization as well as uptake studies; both by batch as well as column methods. The physicochemical characterization of the resins was done using FTIR analysis while the surface morphology of the resins was carried out by scanning electron microscopy. The uptake of the metal ions, typically that of Am(III) and Eu(III), representing the trivalent actinides and lanthanides was studied by batch method. The dry resins and those in contact with nitric acid yielded nearly identical results suggesting minimal effect of the radiolytic products of nitric acid on the resin performance. There was negligible change in the Kd values up to an absorbed dose of 300 kGy beyond which there was sharp decrease. However, the Kd values were still quite large even after an absorbed dose of 1000 kGy. The column performance of the irradiated resins was also assessed by the uptake and elution of Eu(III) ion and though loading was affected, the elution behavior was found to have insignificant effect.