Antimicrobial activity of photocatalysts: Fundamentals, mechanisms, kinetics and recent advances

Photocatalysis has recently been emerged as an effective green solution for antimicrobial disinfection applications. Photocatalytic disinfection has been observed to be efficient in deactivation of extensive varieties of organisms. Numerous gram positive and gram negative bacterial strains such as Escherichia coli, Staphylococcus wrens, Streptococcus pneumonia etc. have been studied. Similarly, fungal strains such as Aspergillus niger, Fusarium graminearum, algal (Tetraselmis suecica, Amphidinium carterae etc.) and viral strains have also been examined in the last decades. The present review sketches the photocatalytic mechanism and provides a brief account of several model organisms used for the disinfection studies. It presents an overview of the major kinetic models such as the Chick's model, Chick-Watson model, delayed Chick- Watson model and Hom's with modified Hom's model. Furthermore, it summarises the importance of operational parameters on the inactivation kinetics and discusses the recent advances of the disinfection results by novel composites and progress in structural or morphological improvements in conventional catalyst. The current review presents a brief overview of the state of the art commercial products utilising photocatalytic antibacterial property. Finally, it details the major international testing standards (ISO, JIS, CEN and ASTM) for photocatalytic antimicrobial applications.