Synthesis and Characterization of Amorphous Silica Nanoparitcles from Aqueous Silicates Uisng Cationic Surfactants

In this work amorphous silica was synthesized using sodium silicate and hydrochloric acid by precipitation according to Stober method. A system of chemical reactions has been developed which permits the controlled growth of silica particles using two different cationic surfactants as the dispersing agents. These surfactants were cetyltrimethylammonium bromide [CTAB] and dodecyltrimethylammonium bromide [DTAB]. The synthesized silicas were characterized by using X-ray diffraction (XRD), Infrared Spectroscopy (IR), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and Dynamic light scattering (DLS). Addition of a dispersing agent in the reaction reduced the particle size of the silica produced. The average size of silica nanoparticles can be finely tuned in the range 148-212 nm by changing the chain length of cationic surfactant. XRD results showed that the synthesized silica was predominantly amorphous.