Review of the mechanism and operational factors influencing the degradation process of contaminants in heterogenous photocatalysis

This paper presents a review of the principles and mechanisms involved in the process of heterogenous photocatalysis. The goal of photocatalysis is to remove persistent organic pollutants as well as microorganisms present in contaminated water. With the help of a semiconductor photocatalyst, solar photons are utilised to generate electron-hole pairs in the oxidation process, forming hydroxyl and superoxide radicals. There are several types of semiconductor photocatalyst available, the most widely used being titanium dioxide (TiO2). The effects of various operating factors influencing the photocatalytic degradation of pollutants, such as pH, catalyst concentration, substrate concentration, light intensity and wavelength, and oxidising agents are discussed. Heterogenous photocatalysis technology has been used in wastewater treatment during the last decade, and has been growing in efficiency ever since. From previous studies of different applications, it will be shown that this process is simple, cost-effective, sustainable and environmentally friendly. However, there are some minor disadvantages associated with its use in water purification, which are presented in this paper.