Photoinitiated Polymerization of 4-Vinylpyridine on polyHIPE Foam Surface toward Improved Pu Separations

The separation of hazardous metals from contaminated sources is commonly achieved with ion-exchange resins. The resins have a high surface area decorated with many ion-exchange sites and thus a high sorption capacity for the analyte of interest. However, these sites are primarily accessed by diffusion which limits the throughput and quality of the separation. Reported herein is a study of monolithic polyHIPE foam columns surface-grafted with a brush of polymer containing ion-exchange functionality for the separation of Pu. It was found that the loading curves of the foam material are steeper than a similarly scaled resin-based column, and the elution profiles of the foams were narrower than the resin, generating more concentrated eluate relative to the amount of Pu loaded onto the foam columns. On a gravimetric basis, the foams had a similar or greater Pu capacity than the resin with fewer ion-exchange sites per unit mass. These characteristics are mainly due to the convective mass transport which dominates the separation in the polyHIPE materials, suggesting that these materials may be useful for more efficient hazardous metal separations.