Sequestration of U(VI) from Acidic, Alkaline, and High Ionic-Strength Aqueous Media by Functionalized Magnetic Mesoporous Silica Nanoparticles: Capacity and Binding Mechanisms

Abstract

Uranium(VI) exhibits little adsorption onto sediment minerals in acidic, alkaline or high ionic-strength aqueous media that often occur in U mining or contaminated sites, which makes U(VI) very mobile and difficult to sequester. In this work, magnetic mesoporous silica nanoparticles (MMSNs) were functionalized with several organic ligands. The functionalized MMSNs were highly effective and had large binding capacity for U sequestration from high salt water (HSW) simulant (54 mg U/g sorbent). The functionalized MMSNs, after U exposure in HSW simulant, pH 3.5 and 9.6 artificial groundwater (AGW), were characterized by a host of spectroscopic methods. Among the key novel findings in this work was that in the HSW simulant or high pH AGW, the dominant U species bound to the functionalized MMSNs were uranyl or uranyl hydroxide, rather than uranyl carbonates as expected. The surface functional groups appear to be out-competing the carbonate ligands associated with the aqueous U species. The uranyl-like species were bound with N ligand as η bound motifs or phosphonate ligand as a monodentate, as well as on tetrahedral Si sites as an edge-sharing bidentate. The N and phosphonate ligand-functionalized MMSNs hold promise as effective sorbents for sequestering U from acidic, alkaline or high ionic-strength contaminated aqueous media.

A Self-Assembled Supramolecular Material Containing Phosphoric Acid for Ultrafast and Efficient Capture of Uranium from Acidic Solutions

“…, 2,3,7 indicating that the presence of U(VI) in PM-9-U(VI). Besides, the PO vibration band shifts from 1108 to 1122 cm −1 , suggesting that there is an interaction between oxygen atom and uranium.…”

“…Moreover, several new and bonds appears at 3117 (O–H stretching vibration), 1676 (OH bending vibration of P–OH), − 1108 (PO stretching vibration), 1033 (P–O stretching vibration of P–O–C), , and 919 cm –1 (P–O–H antisymmetric vibration) ,, which can be ascribed to the phosphate group that also prove that the successful introduction of PA onto MA by the hydrogen bonding. After the adsorption of U­(VI), a new and intense band appears at 908 cm –1 which can be due to the antisymmetric vibration of the UO 2 2+ , ,, indicating that the presence of U­(VI) in PM-9-U­(VI). Besides, the PO vibration band shifts from 1108 to 1122 cm –1 , suggesting that there is an interaction between oxygen atom and uranium.…”

“…Recently, uranium has been widely utilized as a nuclear fuel to produce power in the nuclear industry. However, uranium naturally exists in the form of uranyl ion (U­(VI)) which has dramatic mobility and aqueous solubility, is chemically toxic and radioactive, and threatens human health and environmental safety. , Thus, the recovery of U­(VI) from radioactive wastewater that originates from the process of mining and hydrometallurgy of uranium, spent fuel reprocessing, and the treatment of nuclear waste, is not only desirable for saving uranium resources but also for environmental protection. Presently, various adsorbents, such as metal–organic frameworks (MOFs) (Fe 3 O 4 @ZIF-8, ZIF-8/polyacrylonitrile, UiO-66-AO), supramolecular self-assembly material (SSM), amino-functionalized mesoporous silica SBA-15 (SBA-15-N 2 C 1 ), and polymer (MoS 2 - g -copolymer poly­(diethyl (4-vinylbenzyl) phosphonate- co -maleic anhydride (PDMA)) are employed to selectively eliminate and recover U­(VI) from aqueous solutions.…”

Facile construction of Fe, N and P co-doped carbon spheres by carbothermal strategy for the adsorption and reduction of U(vi)

“…The sorption kinetics of U(VI) on Fe/P-CN-800 was simulated with the pseudo-rst-order, 40 pseudo-second-order, 41 and intraparticle diffusion models 42 (see ESI, S3 †). According to eqn (S2)-(S4), † linear transformed models were employed to t the kinetic data, as shown in Fig.…”

Polymer Nanorings with Uranium Specific Clefts for Selective Recovery of Uranium from Acidic Effluents via Reductive Adsorption

“…Literature reports argue in favor of the adsorption-based scavenging material as the preferred methodology for UO 2 2+ extraction and enrichment, rather than solvent extraction-based processes. − Based on the higher affinity of UO 2 2+ , adsorbents are typically derived using amidoxime, amide, imidazole, organophosphorus, and calixarene, phosphonic acid/phosphazene derivatives for developing a reasonably efficient scavenger for UO 2 2+ . − Such efforts include the use of appropriately functionalized porous organic polymers/COFs, mesoporous carbons, nanostructured or MOF-based materials. ,− Long equilibration time, uncertainty about the influences of nanoparticle on human physiology, and the recent environmental concern of the treated organic/inorganic polymeric materials have limited the use of these reagents/materials for any practical application. Further, the use of any scavenger having a biodegradable polymer has rarely been attempted.…”