Light Driven Microbial Disinfection of Water; Mechanisms, Kinetic Models and Factors Influencing It

Water inhabits microbial pathogens like viruses, algae, fungi, bacteria, and protozoans in it. These microorganisms not only contaminate water but air, soil, as well as food. Their decontamination has become complicated due to the development of a higher degree of antibiotic resistance. Various methods are being utilized to regulate antimicrobial activity and for detoxification of water. Photocatalytic disinfection is considered one of the suitable methods because of its ease of operation, non-toxic nature, and efficiency. For this purpose, photocatalytic nanocomposites are prepared by using several different methods. These nanocomposites deactivate cell walls and other structures of pathogens when exposed to light. The efficiency of this process depends on different factors such as pH, temperature, light source, and concentration of photocatalyst. Particularly, materials like graphene having compact, 2D structures that are preferred for nanocomposite synthesis in combination with other substances because of their properties of high surface area, hydrophobicity, porosity, and electrical and optical properties. This chapter highlights the significance of graphene being used in photocatalytic processes and its application in disinfecting pathogens. Furthermore, the mechanism of photocatalytic disinfection is elucidated, and the parameters which influence this process are explained giving insights into the optimum environment required for maximum efficiency of the prepared photocatalysts. The composites with their methods of preparation and efficiencies under different conditions for disinfecting water from various pathogens are reviewed and disinfection kinetic models including Chick’s model, Chick-Watson model, Delayed Chick-Watson model as well as the methods which are being used for detecting antimicrobial activity are illustrated. Overall, this chapter covers the important areas related to photocatalytic disinfection by using graphene and its derivatives.