Photocatalytic Disinfection of E. coli Using Silver-Doped TiO2 Coated on Cylindrical Cordierite Honeycomb Monolith Photoreactor Under Artificial Sunlight Irradiation

In this paper, TiO 2 and Ag-doped TiO 2 photocatalysts were coated on the cylindrical cordierite honeycomb monolith (CHM) to evaluate their photocatalytic disinfection against Escherichia coli (E. coli) bacteria under artificial sunlight irradiation. The X-ray diffraction (XRD) patterns showed a single-phase anatase structure for TiO 2 samples calcined at 500 °C for 2 h. With the presence of Ag, the bandgap of TiO 2 becomes narrower, and the absorption edge shifts toward the visible region. 6 mol% Ag-doped TiO 2 (6Ag-T) showed a reduction of bandgap energy to 2.2 eV. TiO 2 and Ag-doped TiO 2 solutions were prepared and coated on the channels’ surface of CHM for antibacterial applications. Although monolithic TiO 2 caused a slight decrease in the number of alive E. coli , Ag dopant showed significant improvement in antibacterial properties. 6 mol% Ag-doped TiO 2 coated on CHM (6Ag-T/S10/M) showed strong antibacterial effectiveness against E. coli that the bacterial cell concentration dropped to zero after 1 h of exposure. Impressively, reusability tests with these materials showed superior performance, where the antibacterial remains unchanged after five or seven successive operation cycles. Graphical Abstract