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NaY zeolite molecular sieves have been synthesized using diatomite as a main starting material via a hydrothermal method. In this approach, the mixture of diatomite and Na2CO3 in mass ratio of 1.0/1.46 was first calcined at temperature of 830 °C for about 1.5 h. The calcined materials were then dissolved in water to obtain a solution of SiO2-Al2O3-M2O (M is alkaline meal ions)-H2O. The solution was adjusted to a composition of 15.1 Na2O : 1 Al2O3 : 11.5 SiO2 : 832 H2O by adding Na2SiO3. The solution was used to synthesize NaY zeolite by the crystals seeds (27.76Na2O•1.00Al2O3•25.07SiO2•305.66H2O) via hydrothermal treatment. The hydrothermal temperature is 100 °C and the percentage of added crystal seeds is 10% compared to the solution in volume. The synthesized zeolite was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and nitrogen sorption analysis, and the result showed that a high yield of NaY type with a high degree of crystallization was obtained. Different sizes of the zeolites were obtained by tuning the hydrothermal treatment time. The prepared NaY zeolite exhibits a high efficiency in removing Pb2+ from aqueous solution, and the maximum adsorption capacity is 73.0 mg/g at 25°C.
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