Nucleation and anisotropic growth model for isothermal kaolinite dehydroxylation under controlled water vapour pressure

Kais Nahdi 1 Stéphane Perrin 2, 3, 4 Michèle Pijolat 2, 3, 4 Françoise Rouquerol 5 Najia Ariguib 1 Malika Ayadi 1
1 LACReSNE - Laboratoire des Applications de la Chimie aux Ressources et Substances Naturelles et à l'Environnement
2 SPIN-ENSMSE - Centre Sciences des Processus Industriels et Naturels
3 LPMG-EMSE - Laboratoire des Procédés en Milieux Granulaires
4 ProcESS-ENSMSE - Département Procédés et évolution des systèmes avec solides
5 LCP - Laboratoire Chimie Provence
Abstract : A new kinetic model of kaolinite dehydroxylation is proposed in order to take into account data obtained by gravimetry at 450°C under controlled water vapour pressure ranging from 2.5 to 10 mbar. This model involves a process of random nucleation and anisotropic growth of nuclei. Under the above experimental conditions, the growth of nuclei on the surface of the particles is rapid, whereas the growth towards the inside of the particles is limited by two-dimensional diffusion. This model allowed us to evaluate the 'areic frequency of nucleation' and the 'areic reactivity of growth' for our experiments. The variation of the latter quantity with the water vapour pressure was also obtained by a method based upon a sudden pressure change during isothermal experiments. It is this variation which allows us to conclude that the growth of nuclei into the particle is limited, under our experimental conditions, by the diffusion of hydroxyl groups from the internal interface to the external one.
Keywords : kaolinite dehydroxylation gravimetry nucleation anisotropic
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Article dans une revue
Physical Chemistry Chemical Physics, Royal Society of Chemistry, 2002, pp.1972-1976. 〈10.1039/B107804F〉
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https://hal-emse.ccsd.cnrs.fr/emse-00609806
Contributeur : Andrée-Aimée Toucas <>
Soumis le : mercredi 20 juillet 2011 - 10:34:34
Dernière modification le : mardi 23 octobre 2018 - 14:36:07

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Kais Nahdi, Stéphane Perrin, Michèle Pijolat, Françoise Rouquerol, Najia Ariguib, et al.. Nucleation and anisotropic growth model for isothermal kaolinite dehydroxylation under controlled water vapour pressure. Physical Chemistry Chemical Physics, Royal Society of Chemistry, 2002, pp.1972-1976. 〈10.1039/B107804F〉. 〈emse-00609806〉

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