Evaluation of colloidal silica obtained via the co-precipitation method using octane as an organic phase

The studies were conducted on the production of silica from emulsion systems by co-precipitation from solutions of sodium metasilicate and hydrochloric acid and octane were used as an organic medium. The obtained products were subjected to a comprehensive physicochemical analysis in order to define their dispersive and morphological properties. Particle diameters and polydispersity were determined by the NIBS (non-invasive back scattering) method while the shape and morphology of the particles were established using scanning electron microscopy (SEM). In order to determine the adsorptive properties of the obtained monodisperse silicas, isotherms of nitrogen adsorption/desorption on their surfaces were determined. Using the isotherms, also the specific surface area, the diameter and the volume of the pores were established. In order to define the hydrophilic/hydrophobic character of the products, profiles of wettability and of sedimentation in water were examined. The obtained products were well wettable with water and an increase in their weight depended on the amount of the applied surfactants. The particles of the precipitated silicas manifested a defined, spherical shape and showed a relatively low polydispersity.