A Study on the Role of Nanosilica Seeds on the Synthesis of Silica Colloids

In the current research sodium silicate has been used to synthesize silica colloid by ion exchange process. Deterministic relations for zeta potential, size and solid content have been developed by optimization of three input parameters: seed concentration (0, 1, 2%wt), temperature (30, 55, 80°C) and KOH concentration (0.5, 1, 1.5%wt). Central Composite Design of Response Surface Methodology was used to optimize silica colloid. The goal of this optimization is to achieve the silica colloid with the highest zeta potential, the minimum particle size and the highest solid content. The derived equations and contour plots predict the values of selected independent variables for preparation of optimum silica colloid with desired properties. Based on the fitted models, the optimum silica colloid is prepared by 0.756%wt KOH in 70°C that contains 59.9 %wt SiO2. Also, this silica colloid sample contains a particle size of 11.5 nm and zeta potential of -6.48 mV.