Studies On Photocatalytic Properties Of Doped TiO₂ And Its Antibacterial Properties

Titanium dioxides doped with metal ions (Ag⁺,Cu²⁺,Ni²⁺,Pb²⁺,Bi³⁺) andnon-metal (N,B,S) were prepared by sol-gel method. Bi-compeonent co-doped titaniumdioxides were also synthesized. They were characterized by XRD,FT-IR,UV-Vis DRS,XPS,TG-DTA and so on. Their photocatalytic activities were evaluated by thephotodegradation of methylene blue under visible light. At the same time, the effects ondegradation of methylene blue was studied under the different conditions: different mol.ratios of Ag/Bi, different calcined temperatures, different pH of initial reaction solution,different catalyst amounts, taking Ag-Bi-TiO₂ as the representative sample. In addition,the Ag-Ti-O thin film loaded on aluminium alloy was prepared via dip-coating method,using TiO₂ sol prepared by sol-gel method doped with Ag. Its surface topography andphotoresponse were analysed with XRD,SEM,FT-IR and UV-Vis DRS to know itsmicro-character. The photodegradation activity of methylene blue (MB) solution and oleicacid were investigated under irradiation using the doped film as catalyst. The antibacterialactivities of the samples were evaluated with Escherichia coli and Staphylococcus aureusunder visible light condition. The primary results showed that, obvious red-shift wasobserved in the UV-Vis DRS spectra in doped TiO₂. They revealed well photocatalyticactivity on methylene blue. Silver and bismuth primarily exist in oxide forms inAg-Bi-TiO₂ sample. Its decolourizing rate of the methylene blue solution was up to95.2% with 5h irradiation and mineralization rate was 24.4% and 85.1% with 24hirradiation. Ag-Ti-O films have good photocatalytic activity on methylene blue and oleicacid. Its decolourizing rate of the methylene blue solution was up to 98.4% with 5hirradiation and mineralization rate was 35.2% and 86.5% with 24h irradiation. Oleic acidall can be completely degraded under UV-light irradiation with 1h or visible light with 3h.At the meantime, it exhibited good antibacterial activity on Escherichia coli andStaphylococcus aureus.