Iodine-129 (129I), a long-lived fission product and one of the major constituents of concern at the Savannah River Site (SRS), migrates through the vadose zone into the saturated zone due to its mobility. A recent, as well as previous field samplings, indicate that iodine is being accumulated in the top two feet of the surface soil at the F-Area of SRS’s Fourmile Branch wetland. In this study, two low-cost and environmentally friendly organoclays (PM-199 and MRM) were studied as potential sorbents for in-situ remediation treatment of iodine species, i.e., iodide (I-), iodate (IO3-), in the wetland. The adsorption of iodine species was studied using organoclays MRM and PM-199 as the sorbents. Detailed characterization of the organoclays was carried out before the treatment of iodine species. Approximately 40% of the IO3- was adsorbed to the organoclay PM-199 meanwhile, the I- was mostly (~99%) removed from the aqueous solution within 12 hours. The separation of iodide from the aqueous solution is primarily driven by the strong adsorption onto the PM-199. In contrast, approximately 80% removal of IO3- and I- by organoclay MRM was achieved within 7 days. The results of this study demonstrate that the organoclays can be used to facilitate iodine species adsorption to control the mobility of iodine species in the Fourmile Branch wetlands.

Effective removal of iodine species by organoclays MRM and PM-199

ACS Fall 2021

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