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

Journal Article · Mon Nov 20 00:00:00 EST 2017 · Environmental Science and Technology

DOI:https://doi.org/10.1021/acs.est.7b03778· OSTI ID:1501348

Li, Dien  ^[1]; Egodawatte, Shani ^[2]; Kaplan, Daniel I. ^[1]; Larsen, Sarah C.  ^[2]; Serkiz, Steven M. ^[1]; Seaman, John C. ^[3]; Scheckel, Kirk G. ^[4]; Lin, Jinru ^[5]; Pan, Yuanming ^[5]

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1. Savannah River National Lab. (SRNL), Aiken, SC (United States).
2. Univ. of Iowa, Iowa City, IA (United States)
3. Univ. of Georgia, Aiken, SC (United States). Savannah River Ecology Lab.
4. US Environmental Protection Agency (EPA), Cincinnati, OH (United States). National Risk Management Research Lab.
5. Univ. of Saskatchewan, Saskatoon, SK (Canada)

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 η² bound motifs or phosphonate ligand as a monodentate, as well as on tetrahedral Si sites as an edge-sharing bidentate. Conclusively, 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.

• Research Organization: Savannah River National Laboratory (SRNL), Aiken, SC (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC09-08SR22470
• OSTI ID: 1501348
• Report Number(s): SRNL-STI-2017-00262
• Journal Information: Environmental Science and Technology, Vol. 51, Issue 24; ISSN 0013-936X
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY