Abstract
Three clay samples with different mineral compositions (kaolinite, smectite-kaoline, and smectite-
rich) were used for zeolite synthesis using the method of hydrothermal reactions after fusion
with NaOH. The conditions of hydrothermal crystallization (zeolitization) were found to be at
temperature of 100˚C, and time span between 72 h and 96 h for kaoline and smectite-rich samples,
while 48 h for the smectite-kaolinite sample. The results indicate that zeolites began to crystallize
from clay samples after 48 h, and crystallization increased with increasing time. The synthetic
materials have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM),
fourier transform infrared spectroscopy (FT-IR) and thermogravimetric (DTA/TGA) analysis. The
results indicate that low silica NaX-faujasite type with well-developed octahedral and cubic crystals
was synthesized from the three samples. No big difference in the characterization between the
three synthetic materials was detected, but smectite-kaolinite sample as raw material was relatively
better in crystallization of synthetic zeolite. Applications of the synthetic materials in the
removal of heavy metals proved that the synthetic faujasite has strong effect for removing of Cr3+,
Co2+, Ni2+ and Mn2+ from aqueous solution.