Adsorption of water vapour in natural and modified zeolites

ABSTRACT PhD Thesis ADSORPTION OF WATER VAPOUR IN NATURAL AND MODIFIED ZEOLITES MERYEM SAKIZCI Anadolu University Graduate School of Natural and Applied Sciences Physics Program Supervisor: Prof. Dr. Ertuğrul YÖRÜKO?ULLARI 2004, 139 pages In the present study, moisture contents (%) and time dependent percentage of water uptake of natural zeolite (clinoptilolite) and its Na+, Ca2+, Li+, Mg2*, K% ZH1 (1 N HC1), ZH2 (1 N H2S04), ZH3 (5 N HC1) and ZH4 (5 N H2SO4) forms obtained from Manisa-Gördes region at the o o temperatures of 30 C, 50 and 100 C were investigated. The basic purpose of the study was to determine physicochemical parameters that characterize natural and modified zeolite that can be thought as water adsorbent and to suggest the best model for water adsorption by comparing present models. Natural and modified zeolite forms were characterized by XRD, DTA, TGA, DSC and BET methods. Sorption properties of samples were determined by using average pore diameters, specific surface areas and adsorption isotherms obtained from BET method. The results of the study revealed that adsorption capacities of clinoptilolite increased for modified ones and this is due to the increased surface area. It was found that acid forms of clinoptilolite have the highest water adsorption capacity while K4" form have the least water adsorption capacity. The results of study are compatible with adsorption models of Bish (1988) and White & Bussey (1997) for various salt solutions of modified clinoptilolite. Keywords: Natural Zeolites, Modified Zeolite, Clinoptilolite, Water Vapour Adsorption, Desiccants