Characteristics and properties of surface coated nano-TiO2

Nano-TiO2 was coated with Al2O3, SiO2 and silane coupling agent by chemical liquid deposition. The coating was characterized by Raman spectroscopy, XRD, TEM and FT-IR. The coating content and anti-ultraviolet capacity of nano-TiO2 were measured by XRF and UV-vis spectrometer. The results show that dense coatings containing 5% Al2O3 or SiO2 can be obtained by mixing slurry at pH 10, adding coating reagent and neutralization reagent into the slurry for 60 min at 85–95 °C, and finally aging for 120 min. Noncrystal SiO2 was coated on the surface of nano-TiO2 to form silica gel polymer with a Ti—O—Si bond, while aluminum compound exists in the form of AlOOH and part Al(OH)3. The integrated dense film can shield photocatalysis effectively. The inorganic coating film can increase the wettability for xylene and stability in water. The surface modification of nano-TiO2 will not impair its ability for anti-ultraviolet radiation, and more short band ultraviolet radiation can be absorbed. In addition, the optimal coating amount of silane coupling agent should be less than 3% and the best wettability for xylene can be reached when the amount is 1.2%.