41-9 Organoclay Synthesis and Use in Sorption of Radioisotopes

Session: Paleontology, Stratigraphy, Sediments, and Soils (Posters)

Poster Booth No.: 30

Presenting Author:

Christopher Goellner

Authors:

Goellner, Christopher Bennett¹, Ferguson, Brennan Owens²

(1) Department of Geology, University of Georgia, Athens, GA, USA, (2) University of Georgia, Aiken, SC, ,

Abstract:

Both vermiculite and montmorillonite are used for waste containment due to their absorbent properties, especially for nuclear pollutants. In this study, the sorptive capabilities of vermiculite and montmorillonite were tested for strontium and iodine . Additionally, these clays were modified with organic cations to investigate the potential impact of the modification on the sorption of anionic iodine species. Both strontium and iodine radioisotopes are common co-contaminants associated with nuclear waste but have very different chemical speciations and transport behavior in aqueous environments. Iodine forms predominantly anionic chemical species (iodide, iodate, and organically bound iodine) while strontium favors the Sr⁺² cation. This diversity of chemical species could necessitate the use of specially modified clay barriers. Organically modified clays (organoclays) can alter the sorptive capabilities of clay barriers, making them a promising tool for waste control. The organoclays for this experiment were synthesized using hexadecylpyridinium (HDPy) chloride and hexadecyltrimethylammonium (HDTMA) bromide. These are long-chained ammonium salts that dissolve into organic cations, which exchange with the naturally occurring cations within the clay structure. These modifications can increase sorption due to a combination of greater surface area for binding and the cationic properties of the organic compound, which can make them more attractive for anionic sorbents. For synthesis, each unmodified clay was suspended in each organic solution, allowing for the organic cations to infiltrate the clay interlayer. The clays were then analyzed using elemental analysis for carbon, hydrogen, and nitrogen content and x-ray diffraction (XRD) to observe the elemental and structural changes to the clays. The XRD patterns for both HDPy modified clays revealed visible leftward shifts at low diffraction angle values, which indicate widening in the basal spacing associated with exchange of a larger cation. Additionally, increases of elemental carbon ranged from 0.7% for the vermiculite clays and 7.2% for the montmorillonite clays, suggesting both the presence of organic material within the clay structure and preferential affinity between HDPy and the montmorillonite clays. Batch sorption experiments with iodate demonstrated relatively low sorption on the unmodified clays (<7% sorbed). However, the HDPy vermiculite exhibited 2x greater percent sorption, and the HDPy montmorillonite had 10x greater percent sorption then the unmodified clays. For strontium, the unmodified clays showed decent sorption, which validates the continued use of unmodified clays in remediation.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1, 2026

doi: 10.1130/abs/2026SE-12230

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