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Title
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Chabazite : stable cation-exchanger in hyper alkaline concrete pore water
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Author
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Abstract
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| 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. |
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Language
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English
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Source (journal)
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Environmental science and technology / American Chemical Society. - Easton, Pa
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Publication
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Easton, Pa
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2015
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ISSN
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0013-936X
[print]
1520-5851
[online]
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DOI
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10.1021/ES505346J
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Volume/pages
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49
:4
(2015)
, p. 2358-2365
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ISI
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000349806400047
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Full text (Publisher's DOI)
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Full text (open access)
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Full text (publisher's version - intranet only)
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