The bactericidal and virucidal effect for the photocatalytic action of TiO2 is due to the formation of Reactive Oxygen Species (ROS) including the hydroxyl radical HO·, generated by the synergic system Titanium dioxide-light. Most of the studies led to the same conclusion, namely that the hydroxyl radical HO· is the predominant species involved in the bactericide and virucidal action of photocatalysis.
The hydroxyl radical, having an extremely short duration, must be generated in the vicinity of the membrane to be able to remove the components. Its extremely short lifespan and being produced on a surface make it harmless to people.
The most powerful advanced oxidation systems are based on the generation of hydroxyl radicals. The hydroxyl radical is a very powerful oxidising agent. Because of its strong oxidative capacity, photocatalytic oxidation can effectively sanitize, deodorize, and purify the air, water and other surfaces.
Photocatalysis not only kills the cells of bacteria, but decomposes them. It has been seen that titanium dioxide is more effective than any other antibacterial agent because the photocatalytic reaction takes place even when there are cells that cover the surface and the multiplication of bacteria is active. It becomes active on the surface, bypassing the bio-film created by bacteria. It is therefore effective where traditional chemical sanitizing agents achieve fewer results. In addition, the endotoxin derived from the death of the cell is decomposed by the photocatalytic action. Titanium dioxide does not decompose and shows an antibacterial and virucide long-term effect. In general, disinfection with titanium dioxide is 3 times more effective than what you achieve with chlorine, and 1.5 times more effective than ozone.
In a similar way to bacteria, viruses must be destroyed without causing intollerable damage to the host cells. Enveloped viruses, such as HIV, are generally susceptible to the photo-inactivation, as opposed to non-enveloped viruses: this indicates that it is the viral envelope, rather than nucleic acids, that is the objective of photosensitization.