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

Abstract

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.

Challenges and Advances in the Fabrication of Monolithic Bioseparation Materials and their Applications in Proteomics Research

“…In general, they possess two distinct types of pores, the droplet‐templated pores as “voids” ranging from a few micrometers to hundreds of micrometers and the interconnecting holes as “windows,” which make them as adsorbent materials for enzyme immobilization, water purification, fast separation of proteins in HPLC, even as a filter for bacteria or an active biological scaffold for tissue engineering . Recently, a polyHIPE monolith was prepared with an HIPE containing styrene, divinylbenzene, 4‐vinylbenzyl chloride and sorbitan monooleate, and further modified with a layer of poly(4‐vinyl pyridine) . The resulting monolithic foam could be exploited as ion‐exchange resin for separation of hazardous plutonium from contaminated sources.…”

Leveraging Actinide Hydrolysis Chemistry for Targeted Th and U Separations using Amidoxime‐Functionalized Poly(HIPE)s

“…Despite many reports of poly(HIPE) materials for first‐row transition metal, platinum group metal, and rare earth element sequestration, only a few describe their utility for actinide separations. Recent work by Benicewicz and co‐workers successfully demonstrated the incorporation of vinylpyridine monomers into styrenic poly(HIPE)s resulting in Pu uptake via an anion‐exchange mechanism. In that case, the nitrate associated with quaternized pyridine exchanged with the dianionic hexanitrato Pu(IV) complex, Pu(NO 3 ) 6 2− , formed by contact with 8 M HNO 3 .…”

High-Capacity Poly(4-vinylpyridine) Grafted PolyHIPE Foams for Efficient Plutonium Separation and Purification

“…14−26 Specifically, polyHIPEs with surface-grafted chains of P4VP prepared via photoinitiated polymerization have been studied as a potential replacement for columns of Reillex HPQ for the Pu purification process at the Savannah River Site. 27,28 Conveniently, the backbone of the polyHIPE foam is polystyrene cross-linked with divinylbenzene (a similar chemical composition to the Reillex resin), which is known to have fairly good stability under the harsh acid and radiation conditions used for testing. 4 In batch testing experiments, the foam samples were found to have faster uptake kinetics than the resin.…”

“…27 Testing of similarly prepared P4VP-grafted monoliths under controlled flow conditions showed that the Pu could be eluted from the columns much more efficiently than the resin and despite having a lower anion-exchange capacity (based on nitrogen content due to P4VP), some of the tested foams could adsorb more Pu per unit mass than the resin. 28 These performance improvements are likely owed to the convective mass transport made possible by the large open pore structure afforded by the polyHIPEs. Grafting the chains from the foam surface ensures all ion-exchange functionality is freely available on the surface of the foam, rather than hidden in the bulk of the material (like a resin bead).…”

“…However, preparation of surface-grafted foams using a surface-photoinitiation approach limited the size of columns that could be produced and the amount of grafted P4VP was somewhat unpredictable. 28 To be a viable replacement for anion-exchange resins, the ion-exchange capacity of the foam materials needed improvement.…”