**2.7. Photocatalytic disinfection**

The acceleration of a photoreaction in the presence of a catalyst is referred as photocatalysis. In catalyzed photolysis, adsorbed substrate is used to absorb light. In photogenerated catalysis, electron–hole pairs are created by the photocatalytic activity (PCA) generating free radicals (e.g., hydroxyl radicals: •OH) that have the ability to undergo secondary reactions. Its practical application was made possible by the discovering the electrolysis of water by using of titanium dioxide.

### *2.7.1. Advantages*

The followings are the advantages of photocatalytic disinfection

• Photocatalysis uses capacity for renewable and pollution-free solar energy, thus it is a good replacement for the energy-intensive conventional treatment methods.

