Microwave Heating of Hydrated Zeolites and Application of Zeolites as a Domestic Reusable Desiccant through its Technique
Na-X zeolite easily caused a thermal runaway by microwave radiation of 500W but Ca-X zeolite merely reached ca. 300°C. Mixtures of Ca-X and Na-X reached lower heating temperature with increasing the content of Ca-X and the heating temperature could be controlled (>300°C) by adjusting the content. Since water in X zeolite almost completely desorbs by 400°C, conditions realizing the heating temperature of ca. 400°C were studied. The mixture with the ratio of Ca-X/Na-X=0.9/0.1 was quickly heated to ca. 400°C by the radiation of 10-20 min in the 500 W power and reached the dehydration state up to >90 %. A degradation degree of adsorption capacity of the mixture for water was examined after two and three treatments with the microwave heating. The average degradation degree was 1.4 % per treatment. The properties of the zeolite desiccant with microwave treatment were compared with those of commercial CaCl2 desiccant. It was found that the zeolite desiccant is superior to the commercial desiccant and an application of zeolite to a domestic reusable desiccant, through the heating technique, is promising.
M. Gupta and Christina Y.H. Lim
T. Ohgushi and M. Nagae, "Microwave Heating of Hydrated Zeolites and Application of Zeolites as a Domestic Reusable Desiccant through its Technique", Journal of Metastable and Nanocrystalline Materials, Vol. 23, pp. 195-198, 2005