Photocatalytic comparison of Cu- and Ag-doped TiO2/GF for bioaerosol disinfection under visible light

Photocatalysts, TiO2/glass fiber (TiO2/GF), Cu-doped TiO2/glass fiber (Cu–TiO2/GF) and Ag-doped TiO2/glass fiber (Ag–TiO2/GF), were synthesized by a sol–gel method. They were then used to disinfect Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in bioaerosols under visible light irradiation. TiO2/GF did not show any significant disinfection effect. Both Cu and Ag acted as intermediate agents to enhance separation efficiency of electron–hole pairs of TiO2, leading to improved photocatalytic activity of Cu–TiO2/GF and Ag–TiO2/GF under visible light. Cu in Cu–TiO2/GF acted as a defective agent, increasing the internal quantum efficiency of TiO2, while Ag in Ag–TiO2/GF acted as a sensitive agent, enhancing the transfer efficiency of the electrons generated. The highest disinfection efficiencies of E. coli and S. aureus by Cu–TiO2/GF were 84.85% and 65.21%, respectively. The highest disinfection efficiencies of E. coli and S. aureus by Ag–TiO2/GF were 94.46% and 73.12%, respectively. Among three humidity conditions – 40±5% (dry), 60±5% (moderate), and 80±5% (humid) – the moderate humidity condition showed the highest disinfection efficiency for both E. coli and S. aureus. This study also showed that a Gram-negative bacterium (E. coli) were more readily disinfected by the photocatalysts than a Gram-positive bacterium (S. aureus).

Electron–hole pair separation mechanism of a metal-doped TiO2 systemFigure optionsDownload as PowerPoint slide