Study On Photocatalytic Antimicrobial Of Nanometer Sized TiO₂

Nowadays, clean and sanitary living environment is becoming one of people's goals with the improvement of their lives. In this situation, the world pays much attention to restraining the growth and reproduction of deleterious bacteria, or even to perishing them. As nanometer sized TiO2 powder has preferable photocatalytic activity, it has great potential to be used as antibacterial material. So, it becomes a pivotal field in antibacterial research. In the experiments, stable TiO2 gels containing and not containing silver were prepared by Sol-Gel method with Ti(OC4H9)4. Different kinds of antibacterial powders were prepared by adjusting the content of Ag+ and the heat treatment temperatures. Photocatalytic reactions and antibacterial experiments were carried out to appraise the photocatalytic activities and antibacterial performances of TiO2 samples respectively. With different kinds of tests and measures such as TG-DTA, XRD, TEM and UV-Vis, characters of TiO2 particles were studied, and on the base of this study, factors influencing photocatalytic activity and antibacterial performance of TiO2 were discussed. Furthermore, antibacterial PP polymer containing TiO2 antimicrobial was prepared and its antibacterial performance was investigated. It's found that the influences of C2H5OH quantity, H2O quantity, CH3COOH quantity and hydrolyze temperature on gelatinization time are remarkable. By optimizing the preparation process, an appropriate set of technical parameters has been obtained: n(C2H5OH)/n[Ti(OC4H9)4]=10~12, n(H2O)/n[Ti(OC4H9)4]=3, n(CH3COOH)/n[Ti(OC4H9)4]=2~2.5, and the suitable hydrolyze temperature is between 25~30℃. On the base of this technique, stable TiO2 gel containing silver was prepared by adding AgNO3 stabilized by citric acid. After TiO2 gel was dried in vacuum, grinded into powder, and calcined at different temperatures, nanometer TiO2 powder samples doped or not doped with silver were acquired. The results of photocatalytic degradation of methyl orange show that: TiO2 sample calcined at 500℃has the highest photocatalytic activity. Compared with TiO2 not containing silver, the Ag-TiO2 sample has even higher photocatalytic activity. The most optimal silver content is 1mol%. The results of antibacterial experiments prove that: Due to the antibacterial function of silver, TiO2 doped with silver has antibacterial performance even without ultraviolet radiation. However, TiO2 not doped with silver can't restrain the growth and reproduction of bacteria under the same condition. While radiated by ultraviolet, TiO2 sample possessing high photocatalytic activity has nice antibacterial property, and the antibacterial property of TiO2 improves with the increase of silver when its content stays in a low range. But the antibacterial property improves not evidently after silver content exceeds 1mol%. The reason is that too much metallic silver deposits on the surface of TiO2, restraining the photocatalytic effect. Under this condition, only silver acts as the antimicrobial.