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2689614 
Journal Article 
Preparation of the NaA Zeolite with a High Ca2+ Cation Exchange Capacity by Sol-Gel Method 
He Yan; Cui Xuemin; Liu Leping; Zhang Shang; Zhang Weipeng 
2012 
41 
157-162 
WOS:000314485200043 
We aimed to determine the optimal process parameters for preparation of a NaA zeolite with high Ca2+ CEC through a series of experiments([1]). The NaA zeolite was synthesized with ultrafine Al2O3-2SiO(2) powder as the main raw materials, which was prepared by sol-gel method in case the composition of raw materials was unstable. The relative crystallinity and Ca2+ CEC were chosen as the two standards for determining the optimal parameters. The influences of n(Na2O)/n(SiO2) ratio, n(H2O)/n(Na2O) ratio, crystallization temperature, and crystallization time on relative crystallinity and Ca2+ CEC of the products were studied. The NaA zeolite products were characterized by means of XRD, SEM, and BET techniques. Lastly, the optimal process parameters of the NaA zeolite preparation were determined to be as follows: n(Na2O)/n(SiO2) ratio = 3.0, n(H2O)/n(Na2O) ratio = 20, crystallization temperature = 90 degrees C, and crystallization time = 2 h. NaA zeolites with an average particle size of about 1.5 mu m and a Ca2+ CEC as high as 365.6 mg CaCO3 center dot g(-1) were synthesized. 
NaA zeolite; sol-gel method; relative crystalinity; Ca2+ CEC