Hydratation properties of the dehydroxylated-rehydroxylated smectites
Résumé
Na- and Ca-exchanged Wyoming montmorillonites have been dehydroxylated by heating during 1 hour at 750°C and rehydroxylated by hydrothermal treatment (350°C, 100MPa) in a tuttle type pressure vessel with different staying time. Due to the octahedral cations migration induced by the dehydroxylation, the initial layers which are cv (vacant octahedral sites in cis positions) become tv (vacant octahedral sites in trans positions) after the treatment [1]. This transformation is accompanied by a motion of the interlamellar cations to compensate the local modifications in the distribution of charges [1, 2]. In the dehydroxylated state the cations go down in the hexagonal holes