Production of titania sol
In a flask containing 100 ml of deionized water the 0.7 ml of concentrated nitric acid was added with constant stirring. Then the flask was covered with foil and heated to 70 °C. At the same time the solution of titanium isopropoxide in 2-propanol mixture was prepared, the components being in the amount of 16 ml and 12 ml respectively. The resulting isopropoxide-alcohol solution is slowly poured into the flask with nitric acid. The formation of white precipitate was observed. Thereafter the temperature was increased to 80 °C, and the liquid was kept under constant stirring for 45 minutes. Finally, the heating was turned off, the foil was removed and the mixture was kept under constant stirring for further 5-7 days until the formation of stable sol of titanium dioxide.