Influence of OH- concentration on the illitization of kaolinite at high pressure
The products of hydrothermal reactions of kaolinite at 300°C and 1000 bars were studied in KOH solutions covering an OH- concentration, [OH-], of 1M to 3.5M. XRD patterns indicated a notable influence of the [OH-] on the reaction. At [OH]≥3M, the only stable phase was muscovite/illite. The content o...
| Autores: | , , |
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| Formato: | artículo |
| Estado: | Versión enviada para evaluación y publicación |
| Fecha de publicación: | 2011 |
| País: | España |
| Recursos: | Universidad de Sevilla (US) |
| Repositorio: | idUS. Depósito de Investigación de la Universidad de Sevilla |
| OAI Identifier: | oai:idus.us.es:11441/82384 |
| Acesso em linha: | https://hdl.handle.net/11441/82384 https://doi.org/10.1016/j.clay.2010.11.021 |
| Access Level: | acceso abierto |
| Palavra-chave: | Kaolinite KOH Muscovite/illite Hydrothermal reaction OH− concentration XRD NMR |
| Resumo: | The products of hydrothermal reactions of kaolinite at 300°C and 1000 bars were studied in KOH solutions covering an OH- concentration, [OH-], of 1M to 3.5M. XRD patterns indicated a notable influence of the [OH-] on the reaction. At [OH]≥3M, the only stable phase was muscovite/illite. The content of muscovite/illite was calculated from the analysis of the diagnostic 060 reflections of kaolinite and muscovite/illite. The results showed a linear dependence of kaolinite and muscovite/illite contents with [OH-]. 27Al MAS NMR spectroscopy revealed the formation of small nuclei of K-F zeolite at high [OH-]. Finally, modelling of the 29Si MAS NMR spectra indicated that the Si/Al ratio of the muscovite/illite formed was very close to that of muscovite, at least in the mineral formed at low [OH-]. In good agreement with the XRD data, the quantification of the reaction products by 29Si MAS NMR indicated a linear decrease of the kaolinite content with increasing OH- concentration. |
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