1. Sol-Gel Method: The sol-gel method is one of the most widely used techniques for the synthesis of nanosilica. It involves the hydrolysis and condensation of silicon alkoxides or silicic acid precursors in a solution to form a gel. The gel is then calcined to obtain nanosilica particles. The sol-gel method offers control over the particle size and morphology of nanosilica and allows the incorporation of various dopants.
2. Stöber Method: The Stöber method is a simple and robust technique for the preparation of monodisperse nanosilica spheres. It involves the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in an alcoholic medium in the presence of ammonia or other catalysts. The particle size and size distribution of the nanosilica spheres can be controlled by adjusting the reaction parameters such as reactant concentration and temperature.
3. Precipitation Method: The precipitation method involves the precipitation of nanosilica particles from a solution containing a silica precursor under controlled conditions. This method typically utilizes an alkaline solution to induce the precipitation of silica nanoparticles. The properties of the precipitated nanosilica can be modified by altering the reaction parameters and adding dopants during the synthesis.
4. Aerosol Assisted Methods: Aerosol assisted methods, such as flame synthesis and aerosol spray pyrolysis, are widely used for the large-scale production of nanosilica particles. These methods involve the generation of aerosols of precursor compounds, followed by their combustion or pyrolysis to form nanosilica particles. The aerosol assisted methods offer control over the particle size, morphology, and surface functionalization of nanosilica.

https://morningreported.com/methods-of-preparation-and-application-areas-of-nanosilica/