Chabazite : stable cation-exchanger in hyper alkaline concrete pore water
| Autor: | Johan A. Martens, Sara Bals, Eric Breynaert, Christine E. A. Kirschhock, Leen Van Tendeloo, Gustaaf Van Tendeloo, Benny de Blochouse, Mert Kurttepeli, Wauter Wangermez, André Maes |
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| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Chabazite
Hazardous Waste Cesium Hazardous waste Environmental Chemistry Zeolite Cement Aqueous solution Waste management Ion exchange Chemistry Physics Sodium Temperature Water Sorption General Chemistry Cations Monovalent Hydrogen-Ion Concentration 6. Clean water Refuse Disposal Solutions Chemical engineering Microscopy Electron Scanning Potassium Zeolites Chemical stability |
| Zdroj: | Environmental science and technology |
| ISSN: | 0013-936X |
| Popis: | To avoid impact on the environment, facilities for permanent disposal of hazardous waste adopt multibarrier design schemes. As the primary barrier very often consists of cement-based materials, two distinct aspects are essential for the selection of suitable complementary barriers: (1) selective sorption of the contaminants in the repository and (2) long-term chemical stability in hyperalkaline concrete-derived media. A multidisciplinary approach combining experimental strategies from environmental chemistry and materials science is therefore essential to provide a reliable assessment of potential candidate materials. Chabazite is typically synthesized in 1 M KOH solutions but also crystallizes in simulated young cement pore water, a pH 13 aqueous solution mainly containing K+ and Na+ cations. Its formation and stability in this medium was evaluated as a function of temperature (60 and 85 °C) over a timeframe of more than 2 years and was also asessed from a mechanistic point of view. Chabazite demonstrates excellent cation-exchange properties in simulated young cement pore water. Comparison of its Cs+ cation exchange properties at pH 8 and pH 13 unexpectedly demonstrated an increase of the KD with increasing pH. The combined results identify chabazite as a valid candidate for inclusion in engineered barriers for concrete-based waste disposal. |
| Databáze: | OpenAIRE |
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