2.3. Preparation of powders
The equivalent powders were obtained by aging the residual sol.
In this way, the residual sol was heated in a steam bath and then
the concentrated solution was placed at 60 ◦C for 48 h. The dried
solution was annealed at 500 ◦C for 1 h. By this method, 2 types of
dried bulk powders, Pure TiO2 and Tu/PEG–TiO2, were prepared.