T148 Arsenic, Fluoride, Manganese, and Radiogenic Contaminants in Groundwater Systems—Scientific Knowledge, Public Health Concerns, and Removal Technology II

Wednesday, 28 October 2020
1:30 PM - 5:30 PM
Meeting Rooms

CAPTURE OF URANYL PEROXIDE NANOCLUSTERS INTO PILLARED HYDROTALCITES

Paper number: T148-21
Program: Technical Sessions
Time: 4:35 PM – 4:45 PM

Authors

Abstract

U contamination in the subsurface is a persistent issue at sites around the world, such as locations involved in the Manhattan Project or defunct mining districts. U poses a significant health hazard to humans, with the US EPA having imposed a 30 ppb limit in drinking water. In the presence of H2O2 in alkaline aqueous solutions, U self assembles into large, hollow polyoxometalates (POMs) referred to as uranyl peroxide nanoclusters [1]. These macroions can be relatively large, with diameters over 3 nm, and their surface topologies can be modified through the incorporation of oxyanions such as oxalate or pyrophosphate [1]. These POMs are of interest for green nuclear energy production due to their potential applications in nuclear fuel reprocessing [2].

Layered double hydroxides (LDHs) are a class of layered compounds that have generated considerable interest in the past few decades and have been researched extensively for use in remediating toxic elements and organic compounds [3]. Their applications can be enhanced through expansion of the interlayer to heights of ~4 nm [4], allowing for potential capture of large POMs.

Mg-Al LDHs were coprecipitated with an organic anion acting as a pillar, characterized with PXRD, TGA and ICP-OES, then reacted with aqueous solutions of uranyl peroxide nanoclusters. The greatest removal of U was observed when the initial POM solutions contained pyrophosphate-bearing uranyl peroxide nanoclusters. The batch reactions suggest LDH interactions with uranyl peroxide nanoclusters can be controlled, allowing for storage of U in an intermediate form or released back into solution as a nanocluster. As a non-toxic phase that is easily manufactured, pillared MgAl-LDHs show potential for applications in environmental remediation of U.

[1] Burns, et al. Angew. Chem. Int. Ed. 44 (2005) 2135-2139.

[2] Wylie, et al. J. Nucl. Mater. 473 (2016) 125-130.

[3] Li & Duan. Struct. Bond. 119 (2006) 193-223.

[4] Clearfield, et al. J. Incl. Phenom. Mol. Recognit. Chem. 11 (1991) 361-378.

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-359140

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