The Influence of Thermal Processing on the Sorption of Cs and Sr by Sitinakite

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Microporous and Mesoporous Materials



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The remediation of radioactive isotopes such as Cs+ and Sr2+ from water has been evaluated using sitinakites. The sorption media employed in the remediation of radioactive wastes must have thermal and chemical stability to be useful. The present study investigates the structural stability and adsorption performance of sitinakites under conditions of elevated temperatures between 50 and 550 °C. X-ray diffraction indicates that major structural changes are initiated with heating, reducing the crystallinity of the material. The FTIR results also indicate that simultaneous and irreversible dehydration of the materials occurs with elevated temperatures under the conditions studied. Thermal processing also influences the sorption of Cs+, which decreases rapidly as the temperature increases. Adsorption was reduced by 80% at 550 °C for Cs+, when compared to the material processed at 50 °C and neutral pH. In contrast, the sorption of Sr2+ decreases substantially only when the processing temperature reaches 550 °C under the same conditions. In addition, the sorption of Cs+ and Sr2+ follow different trends as functions of pH after thermal treatment. The sorption of Cs+ decreases as a function of increased processing temperature and higher alkalinity. In contrast, the sorption of Sr2+ decreases with thermal processing; however, overall Sr2+ sorption increases as the pH becomes more alkaline. The sorption differences suggest that Cs+ uptake is structurally driven, while Sr2+ sorption is influenced by both the structure and the surface electrostatics of the material. These results suggest the effectiveness of the materials may be compromised due to changes in structure, hydration, and electrostatic interactions that occur when exposed to elevated temperatures.


Sitinakite; Sorption; Cesium; Strontium


Geochemistry | Mineral Physics



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