Abstract：Silica was prepared by traditional chemical precipitation method using water glass as silicon source and sulfuric acid as precipitant. The modification effect of two processes the in-situ modification preparation and the post-treatment modification was studied. The morphology, size, structure and the modification effect of the modified samples were characterized by scanning electron microscopy, laser particle size analyzer, X-ray diffractometer, thermal analyzer and Fourier transform infrared absorption spectroscopy. N₂ adsorption test and DBP test were used to characterize the degree of space structure.The results show that the modification in-situ modification process is better than the post-treatment process. The average particle size of the aggregated particles after drying is 15.59 μm. The infrared spectra shows that the strength of Si—OH on the modified silica surface is decreased and the hydrophobicity is enhanced. The BET value is 112.7 m²/g and the oil absorption is 3.44 mL/g which indicates that the sample has a high specific surface area and spatial structure.

Keywords: precipitated SiO₂; sodium silicate; in-situ reaction