Zeolite NaA from Brazilian chrysotile and rice husk

Brazilian chrysotile, in its natural form and after acid leaching, and rice husk, submitted to calcination and to acid leaching, were used as a silica source for zeolite NaA synthesis. For comparative reasons, commercial pyrogenic silica was also employed as a silicon source. The raw and chemically modified materials, as well as the resulting zeolites were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and thermal analysis. Zeolite NaA, with high crystallinity and purity, was obtained with all the natural sources, excepting in the case of natural chrysotile. High specific area materials were obtained after Ca2+ exchange. Bigger crystals were observed in the case of natural silicon source.