Pretreatment method of silicon dioxide

The invention discloses a pretreatment method of silicon dioxide. The invention discloses an improved method for preparing pre-hydrophobized precipitated silica from rice hull ash silica. The process is efficient and incorporates almost all of the silica coupling agents used to prepare the pre-hydrophobized precipitated silica into the final product. The invention specifically discloses a method for preparing pre-hydrophobized precipitated silicon dioxide in an aqueous medium. The method comprises the following steps: (1) dispersing silicon dioxide into water under a stirring condition to prepare an aqueous silicon dioxide slurry; (2) adding a phase transfer agent into the water-based silicon dioxide slurry; (3) adding a silicon dioxide coupling agent into the water-based silicon dioxide slurry; (4) maintaining the aqueous slurry at a temperature of at least 20 DEG C for a period of time sufficient to react the silica coupling agent with the silica in the aqueous silica slurry to produce pre-hydrophobized pre