Nucleation and Growth of Chrysotile Nanotubes in H2SiO3/MgCl2/NaOH Medium at 90 to 300 degrees C

Détails

ID Serval
serval:BIB_635D05B2B80E
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Nucleation and Growth of Chrysotile Nanotubes in H2SiO3/MgCl2/NaOH Medium at 90 to 300 degrees C
Périodique
CHEMISTRY-A EUROPEAN JOURNAL
Auteur(s)
Lafay Romain, Montes-Hernandez German, Janots Emilie, Chiriac Rodica, Findling Nathaniel, Toche Francois
ISSN-L
0947-6539
Statut éditorial
Publié
Date de publication
04/2013
Volume
19
Numéro
17
Pages
5417-5424
Notes
ISI:000317894300024
Résumé
Herein, we report new insights into the nucleation and growth processes
of chrysotile nanotubes by using batch and semi-continuous experiments.
For the synthesis of this highly carcinogenic material, the influences
of temperature (90, 200, and 300 degrees C), Si/Mg molar ratio, and
reaction time were investigated. From the semi-continuous experiments
(i.e., sampling of the reacting suspension over time) and solid-state
characterization of the collected samples by XRPD, TGA, FTIR
spectroscopy, and FESEM, three main reaction steps were identified for
chrysotile nucleation and growth at 300 degrees C: 1)formation of the
proto-serpentine precursor within the first 2h of the reaction,
accompanied by the formation of brucite and residual silica gel;
2)spontaneous nucleation and growth of chrysotile between about 3 and 8h
reaction time, through a progressive dissolution of the
proto-serpentine, brucite, and residual silica gel; and 3)Ostwald
ripening growth of chrysotile from 8 to 30h reaction time, as attested
to by BET and FESEM measurements. Complementary results from batch
experiments confirmed a significant influence of the reaction
temperature on the kinetics of chrysotile formation. However, FESEM
observations revealed some formation of chrysotile nanotubes at low
temperatures (90 degrees C) after 14days of reaction. Finally, doubling
the Si/Mg molar ratio promoted the precipitation of pure smectite
(stevensite-type) under the same P (8.2MPa)/T (300 degrees C)/pH (13.5)
conditions.
Mots-clé
chrysotile, growth factors, nanotubes, solvent effects, , thermogravimetric analysis
Création de la notice
08/09/2014 12:50
Dernière modification de la notice
20/08/2019 15:19
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