Chiang Mai Journal of Science

Rice husk ash (RHA) as a raw material was used to synthesize SUZ-4 zeolite via a hydrothermal process in the presence of tetraethyl ammonium hydroxide as the template. The molar ratios of silica from RHA: silica sol were varied as the following: 0:100, 50:50, 70:30, 90:10 and 100:0. The synthesized zeolite was characterized using various techniques including X-ray Powder diffraction, Scanning Electron Microscopy and BET-N₂ adsorption method. The results show that the obtained SUZ-4 zeolite using pure silica sol has a needle-shape crystal having diameter in a range of 0.07 ± 0.02 mm and length in a range of 1.7 ± 0.2 mm, while the SUZ-4 crystal from using 50% RHA has a larger needle-shape than that of pure silica sol, having diameter of 0.2 ± 0.01 mm and length of 5.0 ± 1.5 mm. The crystallite size was shrunk to 0.13 ± 0.01 x 2.8 ± 0.2 mm when 90% and 100% RHA were used. With 50 % RHA, high purity of SUZ-4 was obtained having the same surface area as that of 100 % silica sol. The increase in RHA content did change the pore size distribution due to the competitive formation of Merlinoite zeolite (MER) during the crystallization process.