Studies On The Gelation Kinetics Of Silica Sol

The main objectives of this project are to produce stable silica sol, to study the gelation kinetic during the sol-gel processing and to study the role of different factors to the gelation behavior of silica. The factors that were studied are the concentration and relative humidity. The background of the project is described in Chapter 1. Sol-gel processing consists of two reactions which are hydrolysis and condensation. As a result from the reactions, silica sol will slowly convert to gel. In Chapter 2, which is the literature review provides the theory about sol-gel processing. To achieve the first objective that is to prepare stable silica sol, chemicals which are tetraorthosilicate (TEOS), ethanol, nitric acid and water is mixed together and is left reacted in a flask. This method is used to prepare silica sol at room temperature and pressure to study the effect of concentration and relative humidity. The details of the methodology are described in Chapter 3. In order to provide different relative humidity, different amount of sulphuric acid (in term of volume) is used in different descistors. For all experiments, refractive index is measured for every 24 hours. Refractive index indicates the formation of silica particle in liquid sol. The results obtained from experimental works are discussed in Chapter 4. At the end of this research, it is observed that higher concentration of silica sol reacted faster to convert into gel. In addition, the higher relative humidity provides better condition for hydrolysis and condensation reactions to occur at room temperature and pressure. The conclusion and recommendations for future works is described in the last part of this report, Chapter 5.