Preparation of amorphous silica gel from Algerian siliceous by-product of kaolin and its physico chemical properties

The present work is aimed to achieve valorization of siliceous by-product of Algerian kaolin in the preparation of sodium silicate. This silicate is commonly used as a precursor in silica gel preparation. To prepare sodium silicate, a by-product sample is mixed with sodium carbonate with a molar ratio SiO2/Na2O=3 and heated at high temperature (1000 °C). Hydrochloric acid is then slowly added to the hydrated sodium silicate to obtain silica gel. The siliceous by-product and the prepared silica gel are characterized by XRF, XRD, FTIR and BET. The study of porous texture by Nitrogen Adsorption Technique at 77 K shows that the specific surface area SBET increases in the silica gel compared to those of kaolin byproduct from 5.6 m2 g−1 to 477.9 m2 g−1.