Abstract:

Bentonite reacts with NaOH at high temperature leading to a very reactive starting material for zeolite synthesis. Zeolite 4A has been synthesized by hydrothermal method using these reaction products as raw materials The effect of activation temperature, molar ratio of SiO2/Al2O3,molar ratio of Na2O/SiO2, molar ratio of H2O/Na2O on the properties of the products was investigated by using XRD, SEM and calcium ion exchange capacity. It is found that bentonite reacts with NaOH at 600 ℃ obtained best activated product for zeolite synthesis. The mixed compound as resultant slurry for zeolite 4A having a appropriate composition of : molar ratio of SiO2/Al2O3 =1.5, molar ratio of Na2O/SiO2=3 and molar ratio of H2O/Na2O=50, is then crystallization is carried out at 90℃ for 6 h. Under this optimal condition, zeolite 4A with high degree of crystallinity, small granularity of particles (most of the particle size of zeolite 4A was less than 2 µm) and high calcium ion exchange capacity (314 mg CaCO3/g) was obtained.

Key words: Bentonite,alkaliactivation,zeolite 4A