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

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.