Each 25 cm3 of 0.25 mol dm−3 Ti(OH)4 gel was prepared by
mixing 6.25×10−3 mol of titanium isopropoxide (TIPO) with
an aqueous solution of varying pH with HClO4 or NaOH in
a 25-cm3 volumetric flask at 25◦C. If necessary, NaClO4 was
previously included in the aqueous solutions, so as to adjust its
final concentration to 0.10 mol dm−3. On mixing TIPO with
an aqueous solution, gel-like titanium hydroxide, Ti(OH)4, instantly
precipitated. Thus-formed Ti(OH)4 gels were allowed
to age at 25◦C for stabilizing their pH values and then transferred
to an oil bath preheated to 100◦C for additional aging.
The pH change was followed continuously at regular intervals.