It is an amorphous form of silica (SiO2) obtained by hydrolysis of hexafluorosilicic acid with an ammonia solution. It differs from commercially available precipitated silica because the latter is generally obtained from quartz.
Commercial precipitated silica is generally produced in a two-step process. In the first step, molten sand (quartz) is reacted with sodium carbonate (Na2CO3). The resulting sodium silicate is dissolved in water, producing a solution known as “water glass.” In the second step, the sodium silicate solution is neutralized with an acid (usually H2SO4), thus causing the silica to precipitate.
It has several applications covering a wide range of areas. For example, it is used as a filler in tires, industrial rubber and footwear; as a dispersing agent in coatings, paints and inks; and as an anti-caking agent in the food and pharmaceutical markets.
