Synthesis of nano-sized TiO2 colloidal sol and its optical properties

Nano-sized TiO2 sol was prepared through a wet synthesis process. The synthesis procedure involved hydrolysis of TiCl4, acid treatment, and a SiO2 surface-modifying process. Before surface modification, the TiO2 suspension was treated with acid to remove Na ions, soluble TiO2, and other impurities. The acid treatment of a TiO2 suspension at a higher temperature was proved to be useful for effective SiO2 modification. The colloidal sol provided high transparency in visible light as well as excellent UV-shielding properties. Surface modification of TiO2 particles with SiO2 greatly improved both the dispersing stability in neutral pH and the photostability of TiO2 colloidal sol.