سال انتشار: ۱۳۸۷
محل انتشار: همایش بین المللی ژئولیت ایران
تعداد صفحات: ۷
m gharebaghi – Department of Mining, Metallurgical and petroleum Eng. Amirkabir University of Technology, Tehran, Iran.
m irannejad – Department of Mining, Metallurgical and petroleum Eng. Amirkabir University of Technology, Tehran, Iran.
h ghassed – Department of Mining, Metallurgical and petroleum Eng. Amirkabir University of Technology, Tehran, Iran.
using different concentrations of NaOH solution to dissolve Si source, and with addition of sodium
aluminate as Al source, to prepare initial gel. The chemical analysis of the clinoptilolite samples shows a
SiO2/Al2O3 ratio of 6.29. Before synthesis experiments, the beneficiation methods like desliming and
flotation were applied on the samples to remove impurity, improving the ratio to 5.37. Zeolites are generally
synthesized by the hydrothermal reaction of sodium aluminosilicate gels in alkaline medium using
conventional heating systems. In the synthesis experiments of Hesarbon sample, the effect of important
variables such as reaction time, NaOH concentration, weight of sodium aluminate, clinoptilolite to sodium
aluminate ratio and temperature were studied. The synthesis experiments results demonstrated that NaOH
concentrations in initial gel played an important role in the synthesis. It was found that the higher NaOH
concentration was used, the shorter crystallization time of zeolite A was required. The nucleation and
crystallization rates, as well as the yield of zeolite A increased as the NaOH concentrations increase. It was
found that the zeolite A could be synthesized from clinoptilolite under following conditions: NaOH
concentrations, 3 N; the synthesis temperature, 90 ◦C; the corresponding crystallization time, 8 hours;
clinoptilolite to sodium aluminate ratio 3/25. The products of the reactions were characterized using XRD,
and chemical analysis to confirm zeolite crystallinity and phase purity. The synthesized product SiO2/Al2O3
ratio was 2.4, which is consistent with the ratio of zeolite A. Keywords: Zeolite A, clinoptilolite, Zeolite