Microfibrous mesh coated with titanium dioxide: A self-sterilizing, self-cleaning filter

The utility of metal microfibrous mesh coated with titanium dioxide as a self-sterilizing, self-cleaning filter for air is explored. The low-cost mesh is produced via a roll-to-roll process similar to paper manufacturing. The titanium dioxide is applied by spraying an aqueous suspension of the photocatalyst on the surface of the mesh using an airbrush. Photocatalytic activity comparable to a powder layer is achieved at one quarter of the mass loading. The coating enhanced the separation of Escherichia coli (E. coli) from aqueous suspension, but also led to an increase in pressure drop in an air stream flowing through the mesh. The self-cleaning property of the coated mesh is established by recovery of pressure drop performance lost due to biofilm buildup. This is accomplished via a photocatalytic regeneration process involving exposing the mesh to ultraviolet light in air. Oxidation is confirmed by monitoring CO2 evolution during the regeneration. Scanning electron photomicrographs also provide visual evidence of successful regeneration via photocatalysis.