Abstract: High purity zeolite X was synthesized by hydrothermal method with coal fly ash pretreated by alkaline fusion and centrifugal extraction , the effects of alkali/ash and roasting temperature on the quantity of silicon aluminum dissolution were discussed , the influences of alkalinity , aging time, crystallization time and Si/Al ratio on synthesis zeolite were investigated and the adsorption performance of Pb2+-containing waste water has been researched .The results showed that the highest silicon aluminum dissolution quantity obtained at 680 ℃, alkali/ash =2 .3 and the high purity zeolite X synthesized at SiO2/Na2O=1, SiO2/Al2O3 =3.5, 5 h aging and 16 h crystallization.The obtained zeolite X showed fast adsorption to Pb 2+-containing waste water .The removal rate of Pb 2+can be up to 99 .6%for 30 min at the room temperature in the condition of pH =5, adding 0.23 g/100 mL in 500 mg/L Pb2+solution. The adsorption capacity of zeolite X was 216.8 mg/g.

Key words: coal fly ash;high purity zeolite X;lead ion;wastewater treatment