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

Abstract

The use of anion-exchange resins to separate and purify plutonium from various sources represents a major bottleneck in the throughput that can be achieved when this step is part of a larger separation scheme. Slow sorption kinetics and broad elution profiles necessitate long contact times with the resin, and the recovered Pu is relatively dilute, requiring the handling of large volumes of hazardous material. In this work, high internal-phase emulsion (HIPE) foams were prepared with a comonomer containing a dormant nitroxide. Using surface-initiated nitroxide-mediated polymerization, the foam surface was decorated with a brush of poly(4-vinylpyridine), and the resulting materials were tested under controlled flow conditions as anion-exchange media for plutonium separations. It was found that the grafted foams demonstrated greater ion-exchange capacity per unit volume than a commercial resin commonly used for Pu separations and had narrower elution profiles. The ion-exchange sites (quaternized pyridine) were exposed on the surface of the large pores of the foam, resulting in convective mass transfer, the driving force for the excellent separation properties exhibited by the synthesized polyHIPE foams.

Recent advances in separation applications of polymerized high internal phase emulsions

“…Therefore, adsorption method is a preferred separation method for metal ions because of its simple, rapid, and high efficiency. PolyHIPEs with oxygen‐, nitrogen‐, and sulfur‐containing functional groups, or grafted with EDTA, aniline, pyridine, crown ether, or other organic compounds, have been successfully demonstrated effective in the adsorption separation of various metal ions, including Ag + [36], Cs + [129, 130], Li + [131–135], Rb + [130, 135], Cd 2+ [36, 136–138], Cu 2+ [36, 75,103, 138–143], Hg 2+ [144], Ni 2+ [98], Pb 2+ [72, 136, 142, 145], Sr 2+ [130, 135], Zn 2+ [143], Cr(IV) [146, 147], plutonium ions [148, 149], and rare‐earth metal ions (Ce 3+ , La 3+ ) [150] through direct adsorption or ion‐exchange process.…”

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 .…”

Porous, bicontinuous, and cationic polyelectrolyte obtained by high internal phase emulsion polymerization

“…Particularly, hydrophilic poly (HIPE)s are attractive materials because of their potential applications as 3D scaffolds, catalyst support, adsorption, among others; however, they have shown limited development compared with hydrophobic varieties. In particular, polyelectrolyte poly (HIPE)s have received limited investigation, these porous materials bear ionizable groups or permanent charges in their structure and are good candidates to be applied in the field of superabsorbents and adsorbents for water pollutant scavengers …”

“…In particular, polyelectrolyte poly (HIPE)s have received limited investigation, 8,17,18 these porous materials bear ionizable groups or permanent charges in their structure and are good candidates to be applied in the field of superabsorbents 17 and adsorbents for water pollutant scavengers. 19,20 This work aims to synthesize cationic polyelectrolyte poly (HIPE)bearing quaternary ammonium groups (-N + R 3 ) through an oil-in-water high internal phase emulsion. To date, this type of cationic polymer has been poorly explored, and only one recent publication presented a study of an ammonium-based polyelectrolyte.…”