Crystallization of zeolite a coatings from natural zeolite

An investigation was carried out to determine the possibility of preparing coatings of synthetic zeolites on stainless steel from mixtures containing natural zeolite. Hydrothermal synthesis was applied and the coatings obtained were characterized by various techniques. It was observed that crystalline zeolite A coatings could be prepared from natural clinoptilolite, which provided the silica necessary for zeolite synthesis in the alkaline reaction mixture containing alumina. Zeolite coating formation was affected by synthesis conditions, such as temperature, time, alkalinity, and alumina content of the reaction mixture. The involvement of two simultaneous processes, namely, dissolution/transformation of clinoptilolite in the mixture and reaction on the substrate by the help of dissolved reagents, presents a new approach for zeolite coating preparation. This method may especially provide a means for more economical mass-scale production of zeolite coatings since the synthetic reagents may be replaced with much cheaper natural resources.