Clinoptilolite synthesis and ion exchange

In the present study, the synthesis of pure phased, homoionic formed clinoptilolite at high crystallinity was investigated and ion exchange properties of synthetic clinoptilolite were specified on several cations.In synthesis step, the clinoptilolite was hydrothermally crystallized as a pure phase at 145oC, in 5 days, with 0,5%(wt/wt) seed as Gördes clinoptilolite, using a benchmark composition of 2Na2O:Al2O3:12SiO2:120H2O.In the second step, binary ion exchange equilibrium studies of Na+/NH4+, Na+/Pb2+, Na+/Cd2+, Na+/Zn2+ systems on synthetic clinoptilolite was performed. Ion exchange isotherms were compared with natural clinoptilolite isotherms presented in the literature. According to the isotherms of Na+/NH4+ ion exchange it was observed that the selectivity of synthesis clinoptilolite on ammonium ion was higher than the selectivities of the natural clinoptilolites in the literature. The isotherms of Na+/Cd2+ and Na+/Zn2+ systems were estimated to be sigmoidal. The synthetic clinoptilolite was exhibited high selectivity for cadmium and zinc ions compared to the literature. Despite high preferance of synthetic clinoptilolite for lead ion in Na+/Pb2+ binary system, a significant difference was not determined with respect to the literature.Finally, ternary ion exchange equilibrium studies of Na+/Pb2+/Zn2+, Na+/Pb2+/Cd2+, Na+/Cd2+/Zn2+ and Pb2+/Cd2+/Zn2+ on synthetic clinoptilolit were carried out. In the Na+/Pb2+/Zn2+, Na+/Pb2+/Cd2+ and Pb2+/Cd2+/Zn2+ ternary exchange process, clinoptilolite showed high selectivity for lead and was not affected from the third cation which was presented in the systems. The synthetic clinoptilolite prefered lead in all Az values. In the Na+/Cd2+/Zn2+ ternary exchange, the synthetic clinoptilolite selected both cadmium and zinc ions in the system.