Synthesis and evaluation of actinide imprinted resins

Abstract

Organic resins have previously shown good results with application to actinide separations. Large portions of recent research have been dedicated to the synthesis and evaluation of resins with phenolic-type functional groups. Other recent chemical research with lighter metals has developed a technique known as ion imprinting which can provide greater selectivity for the target metal ion. Initial work with ion imprinting and phenolic-type resins has shown these two areas to be largely incompatible. Identifying the ion imprinting technique as potentially the more valuable of the two, further work was undertaken with resins that incorporate a carboxylic acid-type functionality. These new resins are synthesized via a radical polymerization method, which proved to be very compatible with both actinides and the ion imprinting procedure. Polymer-based resins were synthesized without a metal template as well as ion imprinted, or templated, with U(VI), Th(IV), Np(V), and a resin for use with Am(III). Each of these resins were individually characterized and evaluated for use with their respective target metals. Characterization provides a means of comparing theoretical binding capacities of various resins, which the evaluations define the binding characteristics of interest (capacity, selectivity, kinetics, etc.). Based on the initial results for the selectivity of the U(VI) and Th(IV) ions, a new type of resin was developed in an effort to further increase the selectivity of the resin for the target metal ion. This new resin, known as a "capped" resin, seeks to remove the binding capability of any potential binding sites not involved in the ion imprinting process.

(cont.) Results show that the ion imprinting technique can be successfully applied in the synthesis of resins for actinide separations with good success. The resins created through this process also show an affinity for their target metals over both competing ions as well as ions of similar ionic charge and radii. The removal of so-called random binding sites is also possible, with the addition of a few synthetic steps.