Synthesis and radiometric evaluation of diglycolamide functionalized mesoporous silica for the chromatographic separation of actinides Th, Pa and U

Abstract

The separation of Th, Pa, and U is of high importance in many applications including nuclear power, nuclear waste, environmental and geochemistry, nuclear forensics and nuclear medicine. Diglycolamide (DGA)-based resins have shown the ability to separate many elements, however, these resins consist of non-covalent impregnation of the DGA molecules on the resin backbone resulting in co-elution of the extraction molecule during separation cycles, therefore limiting their long-term and repeated use. Covalently binding the DGA molecules onto silica is one way to overcome this issue. Herein, measured equilibrium distribution coefficients of normal extraction chromatographic DGA resin and a covalently bound form (KIT-6-N-DGA sorbent) are reported. Several differences are observed between the two systems, the most significant being observed for uranium, which demonstrated significantly lower sorption behavior on KIT-6-N-DGA. These results indicate that U can effectively be separated from Th and Pa using KIT-6-N-DGA, a task that could not be completed with the use of normal DGA alone.

Understanding Selectivity of Mesoporous Silica-Grafted Diglycolamide-Type Ligands in the Solid-Phase Extraction of Rare Earths

“…Differently, the presence of nitrates in the Fe 3+ coordination sphere is evident and may thus be associated with either a different extraction mechanism (e.g., presence of different extraction/adsorption centers) or a less favorable ligand-silica environment. Consequently, this observation can explain why the obtained sorbents displayed higher extraction capacity and selectivity toward REEs than other elements. ,,, …”

“…15 To complement our past studies, where we focused on the extraction performance of silica-based hybrid nanosorbents, this work concentrates on deciphering the role of the functional groups that are enhancing the interaction and selectivity of the modified silica sorbents with rare earth elements. 9,15,16,40 In-depth knowledge of the bonding interactions between the sorbents and metals is required since our current understanding of the selectivity and of the adsorption mechanisms remains quite rudimentary. For that purpose, a number of tailor-made nanoporous silica sorbents functionalized with various chelating ligands, such as diglycol-2,4diamido-propyltriethoxysilane (DGA-N), 3,6-dioxaoctanediamido-propyltriethoxysilane (DOODA-N), and furan-2,4-diamido-propyltriethoxysilane (FDGA-N), were selected.…”

Size-Selective Separation of Rare Earth Elements Using Functionalized Mesoporous Silica Materials

“…Ordered mesoporous silica materials are particularly interesting candidates due to their large specific surface area and well-defined pore structures, and can be easily functionalized by organic ligands. In this regard, the three-dimensional cubic mesoporous silica KIT-6 possesses large and interconnected pores, which would facilitate the mass transport during sorption and reduce the risk of pore blocking during functionalization and thus is considered as a promising solid support material in metal ion adsorption. − …”

Application of NMR relaxometry for real-time monitoring of the removal of metal ions from water by synthetic clays

“…24 The development of more sustainable recovery solutions with higher efficiency, lower costs and reduced environmental impact represents an imperative challenge. A valid alternative to LLE is liquid-solid extraction (LSE), 25 based on the use of solid sorbents, such as activated carbon, [26][27][28][29] alumina or metal oxides, [30][31][32][33][34] porous materials, 35 metal-organic frameworks (MOFs) 36 or layered compounds. 37,38 The extraction of metal ions with these solids exploits several metal capture mechanisms (i.e.…”