Investigation of Temperature-Time Characteristics of the Interaction of Modified Silica Gel with Sodium Hydroxide
Autoclave-free and low-temperature method of obtaining liquid glass from modified silica gel is considered. Silica gel, a side product of the production of aluminium fluoride, is amorphous silicon dioxide with admixture of fluorine and aluminium compounds. The methods of silica gel processing into liquid glass with preliminary acid purification from admixtures are analyzed. The physicochemical composition of silica gel was studied by means of IR spectroscopy and X-ray phase analyse. Activation of silica gel with the use of alkaline solution was used to increase the yield of liquid glass and the silicate modulus of liquid glass. The dependence of aluminium content in silica gel on the concentration of alkali in the activation solution was established. It was discovered that the yield of liquid glass is determined by the concentration of admixtures in activation solution. The effect of the concentrations of F <sup>-</sup> and SiF <sub>6</sub> <sup>2-</sup> ion content in activation solution on the silicate modulus of liquid glass was studied. It was concluded that it is reasonable to apply alkaline activation solution to obtain liquid glass from silica gel. The dependences of silicate modulus of liquid glass, its density and yield on temperature and time parameters are presented.