Evaluation of a novel solid phase extraction composite for the removal of actinides from acidic nuclear waste solutions

Abstract

A novel approach for preparing granular solid phase extractants (SPE) for the separation of actinides has been developed, wherein the extractant is directly immobilised in an inert matrix. This allows substantially higher extractant loading in the SPE material than for conventional extraction chromatography resins. This approach utilises polyacrylonitrile (PAN) as the inert matrix material. The well-known actinide extractant octyl (phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) has been impregnated within PAN granules at extractant loadings from 20 to 33 wt. % CMPO. The porosity of the PAN matrix allows the active material to have rapid and complete access to the solution containing the target contaminants, resulting in improved kinetics and higher sorption capacities. The new CMPO-PAN SPE material was prepared in a batch process. Equilibrium batch contact tests were then performed with this material to determine the efficacy for removing plutonium and uranium from acid solutions as well as simulated solutions of tank waste currently stored at the Idaho National Engineering and Environmental Laboratory (INEEL). The potential interference of non-target metals was also investigated. The equilibrium behaviour of the new composite material will be discussed.