Calorimetric Heats of Intrusion of LiCl Aqueous Solutions in Hydrophobic MFI-Type Zeosil: Influence of the Concentration
Résumé
For the first time, we report calorimetric measurements of intrusion of aqueous LiCl solutions in a hydrophobic pure siliceous MFI zeolite (silicalite-1) under high pressure. Our results show that the intrusion heats are strongly dependent on the LiCl concentration The intrusion process is endothermic for diluted solutions (molar H2O/LiCl = 12) as well as for water, but it becomes exothermic for a concentration close to saturation (molar H2O/LiCl = 4). Anal. of the data in the framework of wetting thermodn. shows that besides surface wetting, other phenomena occur during intrusion, such as hydrogen-bond weakening and composition change. In all cases, water is preferentially intruded so that the intruded phase becomes more diluted than the bulk solution In the case of the most diluted solution, only water mols. seemed to be intruded. Furthermore, silicalite-1 is shown to be very stable in the presence of LiCl solution, with no noticeable structural and textural modifications observed after intrusion.
Domaines
| Origine | Fichiers produits par l'(les) auteur(s) |
|---|---|
| Licence |