Preparation of nano-TiO2 from TiCl4 by dialysis hydrolysis

The hydrolysis of TiCl4 was achieved by using a dialysis membrane to make H+ and Cl− penetrate out slowly, which produced hydrogel. By this method, no reactant is required and no by-product occurs. The hydrogel was dried by different methods and calcined to obtain nano-TiO2 powder. The samples were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), BET surface area and pore size distribution. For comparison, TiCl4 was also hydrolyzed to prepare nano-TiO2 by other methods such as heating and adding ammonia. The experiments indicate that hydrolysis and drying have important effects on the properties of product. The hydrogel obtained by dialysis hydrolysis is anatase with a higher phase transformation temperature in calcination and the gel washed with ethanol has better porosity and bigger specific area than the products prepared by other hydrolysis methods and the same washing. In this paper, the drying methods of washing with ethanol and azeotropic distillation with n-butanol were improved by an ensuing rewashing with cyclohexane containing a little of surfactant Span-80 and chemical dehydration with acetic oxide, which further improve the porosity and surface area of nano-TiO2 powder.