The heterogeneous systems 'water-hydrophobic zeolites': new molecular springs

Pressure-volume isotherms have been determined for three heterogeneous 'water-zeolite' systems. The first two concern hydrophobic purely siliceous zeolites: silicalite-1 (F-) and zeolite beta (F-); the third comprises a more hydrophilic commercial zeolite of the type ZSM-5. The P-V diagram for the water-silicalite-1 (F-) system is characterized by a plateau corresponding to the intrusion of water inside the pores of the solid. During the release the phenomenon is reversible. This system, which is able to accumulate and restore superficial energy, constitutes a molecular spring. For zeolite beta the P-V curve displays a plateau during the compression, but during the release, the phenomenon is not reversible. In that case, the system absorbs mechanical energy and acts as a bumper. The third system, based on the more hydrophilic ZSM-5 zeolite shows a linear isotherm without any plateau. These results open new applications perspectives in the field of the energetics for hydrophobic zeolites in contact with water. To cite this article: V. Eroshenko et al., C. R. Physique 3 (2002) 111-119. (C) 2002 Academic des sciences/Editions scientifiques et medicales Elsevier SAS.