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Simerjeet Gill1 Mohamed Elbakhshwan1 Clément Cabaud2 Agnes Grandjean2 Siyu Yao1 Eli Stavitski1 Klaus Attenkofer1 Lynne Ecker1

1, Brookhaven National Laboratory, Upton, New York, United States
2, Alternative Energies and Atomic Energy Commission, Marcoule, , France

Radiocesium is one of the most radiotoxic waste water contaminants for human health produced routinely in the nuclear reactors and in accidents such as Fukushima Daiichi. One of the popular methods for removing radiocesium is using Iron ferrocyanide based compounds - Prussian Blue Analogous (PBA) as sorbents for Cesium (Cs) [1-2]. Although Cs sorption properties of various PBAs have been studied, sorption mechanisms involved remain unclear. This can be attributed to the fact that Cs sorption experiments have not been performed under consistent conditions and there is lack of detailed characterization studies using a systematic test matrix.

Preliminary studies indicate that depending on the transition metal in the PBA structure [1], and the ratio K/Cs, the Cs sorption properties and selectivity of the PBA are different. In our current approach we utilize synchrotron based X-ray absorption spectroscopic methods to study the local and chemical structure of the PBAs containing different transition metal ions (Ni2+, Co2+ and Cu2+). Extended X-ray Absorption Fine Structure (EXAFS) and X-Ray Absorption Near Edge structure (XANES) are used to investigate the local coordination environment and chemical structure of PBAs. In addition, the effect of exposure to an acidic environment and changes in local and chemical structure after Cs adsorption is reported. Characterizing the local coordination environment and chemical structure of different PBAs will help better understand the structural stability and Cs sorption capacity of PBAs. This knowledge gained will further provide fundamental understanding of sorption mechanisms involved in Cs extraction as well as aid the design of the next generation PBA sorbents for Cs removal from nuclear waste.

References:

Agne`s Grandjean, Carole Delchet, Jeremy Causse, Yves Barre, Yannick Guari, Joulia Larionova, The Journal of Radioanalytical and Nuclear Chemistry, 2016, 307, 427–436
Merwen Aouadi, Giulia Fornasieri, Valerie Briois, Pierrick Durand, and Anne Bleuzen, Chemistry – A European Journal, 2012, 18, 2617 – 2623

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