Antibacterial properties of photochemically prepared AgTiO₂ membranes

Biofouling reduces the membrane performance and has become a problem in many applications. One of the strategies to reduce biofouling is to apply antibacterial materials to the membrane surface, which prevents the attachment and growth of microorganisms. In this study, the surface of flat ceramic supports was covered with TiO₂ powder, and silver was applied by photoreduction using a CH₃COOAg solution at room temperature. After the photoreduction, AgO_x and metallic silver were found on the TiO₂ as analyzed by XPS. While a negligible amount of silver was released from the prepared AgTiO₂ membranes into water, the dissolution of silver was enhanced in a 0.09 M NaCl solution. The AgTiO₂ membranes inhibited the growth of Escherichia coli in dark conditions. The inhibition cannot be explained only by the concentration of silver ions released from the membranes. Microscopic observation showed that direct contact with AgTiO₂ kills E. coli. The results showed the possibility of improving the antibacterial activity of membranes by applying an AgTiO₂ coating.