Heterogeneous photodegradation of industrial dyes: An insight to different mechanisms and rate affecting parameters

[Display omitted] •Photodegradation (PD) is a solar-induced waste removal from liquid media.•Based on the choice of catalysts. PD can be homogeneous or heterogeneous.•The conventional mechanism involves the generation of photoexcitons within the photoactive material.•Type I, Type II and Z-Schemes are few new establishing mechanisms for hybrid and heterostructure systems.•The physicochemical nature of material and experimental parameters such as time, catalyst dose, medium pH etc. are PD rate affecting factors. The removal of wastes through solar-induced technologies is gaining extensive momentum over the last few years. Photocatalytic (PC) removal of dyes and other waste products from the main stream and aquatic media is considering industrially feasible technologies. Photocatalytic degradation (PD) could economically convert complex molecules into smaller, non-toxic, and lower molecular weight species through photo-assisted redox reactions. Mechanistically, PD process is based on the production of highly reactive, photogenerated hydroxyl and superoxide anion radicals that attack dye molecules and completely mineralize it into more unaffected species, such as CO2 and H2O. This advance technology has advantages over other conventional methods in terms of simplicity, complete pollutants mineralization, no harmful byproducts, cost-effectiveness and reducing contaminants at parts per million (ppm) and parts per billion (ppb) level. The aim of this review is to provide a thorough overview of heterogeneous PD with the literature support. The first section of the review will address the basic principle and materials utilization. This will be followed by a brief section on the different mechanisms reported for PD over the years with suitable examples. Finally, an overview will be provided to various parameters, which influence the process and mechanism pathway. This review aims to not only educate the beginners in the field of PD but also target experienced researchers, who are involved in heterogeneous PD and predicting mechanistic studies.