ADSORPTION-ISOTHERM OF WATER-VAPOR AND ITS LARGE HYSTERESIS ON HIGHLYORDERED MESOPOROUS SILICA

The first and second adsorption-desorption isotherms of water vapor on a new mesoporous material derived from kanemite have been measured. T he isotherms show unusual type V isotherms and large hysteresis. The t ype V isotherms, which have never been observed for the other adsorbat es, suggest that the mesoporous material has a hydrophobic surface, al though the hydrophobicity decreased after treatment with water vapor b ecause of rehydration of the surface. The significantly large hysteres is could be explained by the difference in contact angle between adsor ption and desorption. (C) 1996 Academic Press, Inc.