粉煤灰合成纳米Y沸石及其吸附Cr(Ⅵ)动力学的研究

Synthesis of nano zeolite Y from fly ash and study on its adsorption kinetics to Cr(Ⅵ)

粉煤灰用碱煅烧并通过超声辅助老化和原位水热法制备了Y型纳米沸石(NFA-Y),该工艺中不添加任何有机模板剂和其他硅铝源。利用XRD、SEM和BET分析了合成的纳米Y沸石的形貌、结晶度、结构和比表面积,分析了超声时长对Y沸石形貌和晶相的影响。结果表明,超声老化有利于水热合成纳米Y沸石,使其形貌更规则、粒子分散性更好、晶粒可能更小。合成的沸石比表面积为508 m^(2)/g,孔体积为0.342 cm^(3)/g,晶粒尺寸约为80 nm。通过静态吸附实验探究了Y型沸石对Cr(Ⅵ)的吸附特性,结果表明,其吸附动力学符合准二级动力学模型。

Zeolite Y nanoparticles(NFA-Y)is obtained through calcining fly ash by alkaline,and applying ultrasound-assisted aging and using situ hydrothermal synthesis method without using any organic template,Si source or Al source.The morphology and crystallinity,structure,specific surface area of the obtained zeolite Y nanoparticles is determined by means of X-ray powder diffraction(XRD)analysis,scanning electron microscopy(SEM)and nitrogen adsorption surface analyzer(BET).The effects of the time spent in ultrasonic aging on the morphology and crystallinity of zeolite Y are investigated.Experimental results demonstrate the ultrasonic aging is helpful to hydrothermal synthesis of nanocrystal zeolite Y,making it have a more regular morphology,better dispersion of particles and possibly smaller crystal sizes.The zeolite Y synthesized under the optimal conditions has a specific surface area of 508 m^(2)·g^(-1),a pore volume of0.342 cm^(3)·g^(-1),a crystal grain size of 80 nm.The adsorption characteristics of zeolite Y to Cr(Ⅵ)in aqueous solution are studied via static adsorption experiments,and it is shown that it is in accordance with the quasi second order kinetic model.