Preparation and Growth of Silica Sol from Sodium Silicate

The formation of silica sol from sodium silicate solution and the growth of silica sols were investigated in this study. The content of 2% in sodium silicate solution was proper to oxidize sodium silicate with sulfuric acid. After the removal of sodium ions in sodium silicate solution, the pH of silicate solution had to be controlled above 9 for a stable silicate solution. The silica sol, which size is about 10 nm, could be prepared by heating the mixed solution of sodium silicate and silicate solution removed sodium ions at pH 10 and 80. And the silica sol grew into about 50 nm as silicate solution was added to silica sol solution.