Abstract: Zealite 4A was synthesized by a onestep alkalidissolved hydrothermal method with bentonite as raw material. The effects of n_Na2O∶n_SiO2, n_H2O∶n_{Na2O, nSiO2∶nAl2O3, synthesis time and temperature on the properties of the products were investigated by means of XRD, SEM and calciu m ion exchange capacity. The optimum conditions for synthesizing zeolite 4A are nNa2O∶nSiO2=2, nH2O∶nNa2O=60和nSiO2∶nAl2O3=1.5, a crystallization temperature of 90 ℃ and a reaction time of 6 h. Under the optimal conditions, zeolite 4A with a high degree of crystallinity, a small granularity of particles (most of the particle size of zeolite 4A was less than 2 μm) and a high calcium ion(CaCO3)exchange capacity (293 mg/g) was obtained.}

Key words: bentonite, onestep alkali dissolve, zeolite 4A, influence factor