The development of the hierarchical zeolites by simple and environmentally friendly methods has garnered considerable attention due to their wide application field. In the present work, the effect of the geothermal nanosilica pre-treated by ultrasound or mechanical stirring on the hierarchical structure zeolite synthesis was studied. The effects of the temperature and time crystallization on the zeolite properties were evaluated. Additionally, the X zeolite was evaluated in the dehydration of aqueous solutions of ethanol. The zeolites were characterized by XRD, TEM, FT-IR and nitrogen physisorption. According to the results, the sonochemical pre-treatment of the geothermal nanosilica promotes the formation of nanozeolites and reduces the crystallization time of X zeolite compared to conventional synthesis. The morphology of X zeolite was of nanocrystals of rod-like shape of 25 nm, it presented micro- and mesopores and considerable external surface (50% of the BET surface area). The water adsorption capacity from aqueous solutions of ethanol was influenced by the textural properties, the framework and chemical composition of the zeolite, with the X zeolite synthesized by nanosilica pre-treated by ultrasound exhibiting more affinity and selectivity for water molecules. The simplicity of the methodology for hierarchically structured X zeolite spreads the possibility to synthesize other zeolite type for specific applications.
Keywords: Geothermal nanosilica; Ultrasound; X zeolite; Mesoporosity; Dehydration; Hierarchical structure