Production of Precipitated Nano-Silica from Granite Waste

Precipitated nanosilica has diverse applications in advanced industries. One method for producing precipitated silica is through direct dissolution from mineral sources. This study investigates the production of nanostructured precipitated silica from granite waste powder. Initially, in the dissolution stage with sodium hydroxide, the effects of parameters such as solvent concentration, temperature, stirring speed, time, and sample mass were examined. The results showed that under optimal dissolution conditions (1.5M sodium hydroxide concentration, 80°C, 2.5h, and 900rpm stirring speed), only 0.76g of a 20g sample dissolved. In the precipitation stage, the effects of parameters like pH, temperature, time, and stirring speed were investigated. The results indicated that under optimal precipitation conditions (pH 7, 60°C, 1.5h, 1000rpm stirring speed), approximately 0.149g of nanostructured silica was obtained from the 0.76g of dissolved material. Both the dissolution and precipitation yields were very low, indicating the stability of silica in the granite sample. To enhance the efficiency, pressure dissolution, and calcination of the mineral material should be considered. Characterization of the produced precipitated silica using XRD, FTIR, BET, and SEM analyses revealed that it has the desirable quality for various industrial applications, including tire manufacturing.