SREL Reprint #3357

Functionalized magnetic mesoporous silica nanoparticles for U removal from low and high pH groundwater

Dien Li1, Shani Egodawatte2, Daniel I. Kaplan1, Sarah C. Larsen2, Steven M. Serkiz1,3,
and John C. Seaman4

1Savannah River National Laboratory, Aiken, SC 29808, USA
2Department of Chemistry, University of Iowa, Iowa City, IA 52242, USA
3Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, USA
4Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802, USA

Abstract: U(VI) species display limited adsorption onto sediment minerals and synthetic sorbents in pH <4 or pH >8 groundwater. In this work, magnetic mesoporous silica nanoparticles (MMSNs) with magnetite nanoparticle cores were functionalized with various organic molecules using post-synthetic methods. The functionalized MMSNs were characterized using N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), 13C cross polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy, and powder X-ray diffraction (XRD), which indicated that mesoporous silica (MCM-41) particles of 100-200nm formed around a core of magnetic iron oxide, and the functional groups were primarily grafted into the mesopores of ~3.0nm in size. The functionalized MMSNs were effective for U removal from pH 3.5 and 9.6 artificial groundwater (AGW). Functionalized MMSNs removed U from the pH 3.5 AGW by as much as 6 orders of magnitude more than unfunctionalized nanoparticles or silica and had adsorption capacities as high as 38mg/g. They removed U from the pH 9.6 AGW as much as 4 orders of magnitude greater than silica and 2 orders of magnitude greater than the unfunctionalized nanoparticles with adsorption capacities as high as 133mg/g. These results provide an applied solution for treating U contamination that occurs at extreme pH environments and a scientific foundation for solving critical industrial issues related to environmental stewardship and nuclear power production.

Keywords: Acidic and alkaline groundwater; Magnetic mesoporous silica nanoparticles; Surface functionalization with organic molecules; Uranium removal

SREL Reprint #3357

Li, D., S. Egodawatte, D. I. Kaplan, S. C. Larsen, S. M. Serkiz, and J. C. Seaman. 2016. Functionalized magnetic mesoporous silica nanoparticles for U removal from low and high pH groundwater. Journal of Hazardous Materials 317(2016): 494-502.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).