Kinetics of sol-gel transformation for the preparation of TiO₂ ultrafiltration membrane

The sol-gel technique is considered to be one of the most practical methods for producing ceramic membranes, and the properties of the sols could affect the microstructures of the desired products. Especially, optimized viscosity and a short gelation time can reduce the sol particles infiltrate into the pores of the support. So how to control the forming process of the gel is essential for fabricating the membranes. In this paper, we developed a kinetic equation of sol-gel transformation to study the relationships between viscosity and time of titanium sol systems by using N, N-Dimethylformamide (DMF) as solvent. Both the growth process of the sol particles and activation energy of the process were investigated according to the kinetic curves. The results indicate that the viscosity of sols decreases with the increment of R and temperature, but increases with r_w, at the same time the gelation time decreases with r_w, temperature and R. Furthermore, the growth of sol particles versus time accord with the NLG model, and the activation energy of gelation process decreased with R. When R changed from 2 to 6, the activation energy was decrease from 12.48KJ/mol to 9.35KJ/mol. According to the analysis of the results of the sol-gel transformation, a shorter gelation time could be obtained by increaseing the r_w, R and the gelation' temperature.