碱熔融-微波晶化法合成粉煤灰沸石及其对Cd^(2+)的吸附

Synthesization of Fly-Ash Zeolite by Alkali Fusion-Microwave Crystallization Process and Adsorption to Cd^(2+)

以粉煤灰为主要原料,采用碱熔融—微波晶化法合成粉煤灰沸石。采用XRD,SEM,TEM等技术表征了粉煤灰沸石的微观结构,并对其吸附Cd^(2+)的性能进行了研究。表征结果显示,粉煤灰沸石主要由X型沸石、P型沸石和铝组成,粉煤灰沸石中有排列规则、呈蜂窝状的孔穴和孔道存在,其孔穴和孔道大小分布均匀,致密。粉煤灰沸石的比表面积为108.49 m2/g,平均孔径为3.779 nnm,孔体积为0.221 mL/g。实验结果表明,在溶液pH为7、吸附时间30 min的最佳吸附条件下,Cd^(2+)去除率均大于94%。粉煤灰沸石对Cd^(2+)的吸附可很好地用二级动力学方程进行拟合,相关系数为0.999 99。可用Langmuir等温吸附模型描述该吸附过程,该吸附过程是单分子层吸附,主要是化学吸附,粉煤灰沸石对Cd^(2+)的饱和吸附量为49.261 mg/g。

Fly-ash zeolite was synthesized by alkali fusion-microwave crystallization process using fly ash as raw material, and characterized by XRD, SEM and TEM. Its adsorption capability to Cd2. was also studied. The characterization results indicate that： The prepared fly-ash zeolite mainly consist of X type and P type zeolite and A1, and is full of uniform and regular holes and pores; The specific surface area, average size and pore volume of the fly-ash zeolite are 108.49m2/g, 3.779 nm and 0.221 mL/g, respectively. The experimental results show that under the optimum adsorption conditions of solution pH 7 and adsorption time 30 min, the adsorption rate of Cd^2＋ is more than 94%. The adsorption of Cd^2＋ by fly-ash zeolite fits the secondary reaction kinetics equation with 0.999 99 of correlation coefficient. The adsorption process can be described by Langmuir isothermal adsorption model with 49.261 mg/g ofthe saturated adsorption capacity, which indicates that the reaction is a process ofmonolayer adsorption and mostly chemical adsorption.