Thermal behavior of heulandites and clinoptilolites of Western Anatolia

Selected samples of heulandites and clinoptilolites from different zeolitized formations in Western Anatolia(Turkey) have been examined by differential thermal(DTA) and thermogravimetric(TGA) techniques. Heulandites show three endothermic peaks at temperatures 115°C, 230°C and about 400°C and an exothermic peak 330°C. The collapse of heulandite structure occurs at about 430°-500°C. The DTA curves of heulandites which do not show any polymorphism were almost the same as those which do show polymorphism. Clinoptilolites with Na+ K/Ca+ Mg ratio of about one show an endothermic reaction at 230°C whereas clinoptilolites with Na+ K/Ca+ Mg ratio bigger than one do not exhibit this reaction on their DTA curves. Structure of clinoptilolites persists up to 700°-750°C in our experiments. All samples dehydrated in stepwise manner. Heulandites dehydrated at higher temperatures than clinoptilolites. Clinoptilolites retain water to higher temperatures as their divalent cation content increases.