Radiation stability of two extraction chromatography resins containing aza-crown-based diglycolamides used for Am(III) uptake

Abstract

The radiolytic stability of two extraction chromatography resins with multiple diglycolamide arms was investigated by exposing them to gamma radiation and carrying out uptake studies of Am(III) from acidic feeds. The resins contained aza-crown-based diglycolamide (DGA) ligands, viz., triaza-9-crown-3-N,N’,N”-trisdiglycolamide (TAM-3-DGA) and tetraaza-12-crown-4-N,N’,N”,N’”-tetrakisdiglycolamide (TAM-4-DGA), where the DGA moieties were grafted to the ‘N’ atoms of the macrocyclic ring. These two resins showed excellent performance for the separation of Am(III) from radioactive feed solutions and radiation stabilities were evaluated under a reasonably high gamma ray dose of 1000 kGy. The irradiated resins were employed to recover Am(III) from the acidic feeds in order to evaluate the radiation resistance of the sorbent. The irradiated resins yielded large distribution coefficients for the uptake of Am(III) in the acidity range of 0.5 M – 6 M HNO₃. Different physicochemical properties of the irradiated resins vis-à-vis the pristine resins were evaluated to establish their radiation stabilities. Recycling possibility of the resins was ensured in 5 successive cycles of sorption and desorption. Column studies were carried out using an Am(III) tracer spiked feed containing Eu carrier. The results support the possible application of the two TAM-n-DGA resins (n = 3 or 4) for the separation of Am(III) from radioactive waste solutions without any issue of recycling and radiation stability.