Radiolytic stability of some recently developed ion exchange and extraction chromatographic resins containing diphosphonic acid groups

The effect of Co-60 irradiation on the Diphonix(TM), Diphosil and Diphonix-CS chelating ion exchange resins, and on two Dipex(TM) extraction chromatographic resins containing the P,P'-di(2-ethylhexyl) methanediphosphonic acid (H2DEH[MDP]) impregnated in the pores of a polymeric support (Dipex-1) and of silica (Dipex-2), respectively, has been investigated. The resins have been irradiated while in contact with HNO3 (Diphonix, Diphosil and Dipex resins) or NaOH (Diphonix-CS resin) up to an absorbed dose of about 200 Mrad. As a probe of the resin radiolytic degradation, metal uptake (both equilibrium and kinetics) and capacity measurements have been performed. Our results show that the Diphonix-CS resin properties are practically unaffected by irradiation under the experimental conditions used in this work. The Diphonix, Diphosil, and especially the Dipex resins suffer substantial capacity losses, but their affinity for actinide ions is not seriously compromised. On the other hand, the kinetics of metal uptake by the silica based Diphosil and Dipex-2 resins becomes substantially slower indicating that, from a radiolytic degradation standpoint, polymeric materials perform better than silica as supports for H2DEH[MDP] containing extraction chromatographic resins.