粉煤灰制备NaA型分子筛及其对铅离子的吸附性能研究

Preparation of NaA zeolite with fly ash and its adsorption properties for lead ions

  • 摘要: 以粉煤灰为原料,采用碱熔-水热法合成NaA型分子筛。通过单因素试验探究了水热温度、水热时间、碱浓度、碱灰比对制备分子筛的影响,采用静态饱和吸水量和钙离子交换量对所制备分子筛的性能进行评价。结果表明:水热温度100 ℃、水热时间5 h、NaOH浓度2.73 mol/L、碱灰比2.8有利于NaA型分子筛的合成,其钙离子交换量最高可达374.63 mg/g。利用合成的NaA型分子筛对液相中的铅离子进行吸附研究,在分子筛投加量1 g/L、溶液pH值6.2、吸附温度25 ℃、吸附60 min时,吸附容量(Qe)最高可达471.51 mg/g;分子筛的吸附等温线更加符合Langmuir等温线模型,饱和吸附容量(Qm)可达580.18 mg/g。

     

    Abstract: This study synthesized NaA zeolite by alkali melting-hydrothermal method based on fly ash as raw material. The effects of hydrothermal temperature, hydrothermal time, alkali concentration and alkali/FA mass ratio on the preparation of zeolites were investigated by single factor experiments, and the performance of the prepared zeolites was evaluated by water adsorption capacity and Cation Exchange Capacity (CEC) value.Results show that it is beneficial to the synthesis of NaA zeolite under hydrothermal temperature of 100 ℃, hydrothermal time of 5 h, NaOH concentration of 2.73 mol/L, and alkali/FA mass ratio of 2.8, in which the highest CEC value can reach 374.63 mg/g. The adsorption of Pb(Ⅱ) in liquid phase was studied by using the synthetic NaA zeolite. The adsorption capacity was up to 471.51 mg/g with 1 g/L dosage of zeolite, at pH 6.2 and 25 ℃ of adsorption temperature and the adsorption time was 60 min.The adsorption data of Pb(Ⅱ) by NaA zeolite was fitted better with Langmuir model, and the saturated adsorption capacity of Pb(Ⅱ) could reach to 580.18 mg/g.

     

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