Production improvement of aqueous solutions of nanosized silica

Abstract

The article deals with the method for obtaining aqueous solutions of silica nanoparticles based on sol-gel technology, namely, products of hydrolysis of silicon alkoxides and their polycondensation in an alcohol medium. In order to prevent polymorphic changes and dehydration of SiOH-groups, preference was given to low-temperature and vacuum methods. To combat the excessive foaming ability of surfactants and replace the solvent (alcohol with water), a method of distillation was proposed for partial supply of dry steam with air and water. To separate aqueous surfactant solution (tween-80), a method of oil flotation with petroleum ether addition, characterized by its low solubility, both in water and in alcohol, was proposed. The specifications of obtained nanosilica of aqueous solutions can be estimated using optical spectrophotometry, for which the concentration and size coefficients of the Geller Equation for this system were determined. The optimum concentration of SiO2 in the system was also determined when no particles above 100 nm were formed. Methods for the reagents reuse of ethanol, petroleum ether and tween-80 were proposed.