Recent advances in photocatalysis for environmental applications

Advanced Oxidation technologies (AOTs) are gaining attention as an effective waste water treatment methodology capable of degrading diverse spectrum of recalcitrant organic contaminants and microbes. Undoubtedly, photocatalysis is a promising AOT to alleviate the problem of water pollution. Despite recent research into other photocatalysts (e.g. ZnO, ZnS, Semiconductor-Graphene composites, perovskites, MoS_2, WO₃ and Fe₂O₃), titanium dioxide (TiO₂) remains the most popular photocatalyst due to its low cost, nontoxicity and high oxidising ability. Moreover, titania photocatalysts can easily be immobilized on various surfaces and be scaled up for large scale water treatment. The current review aims to highlight recent advancements in photocatalytic AOTs with main emphasis on TiO₂ photocatalysis. This review also discusses the use of TiO₂ photocatalysis for water and waste treatment, treating contaminants of emerging concern (CECs), pesticides, endocrine disrupters (EDs) and bacteria using both UV and visible light irradiations. It was concluded that with efficient photoreactor configuration and further studies on the photocatalyst regeneration, TiO₂ photocatalysis is a viable option for the reclamation of agricultural/irrigational waste water. Novel doped photocatalysts such as ZnS-CuS-CdS, carbon spheres/CdS, g-C₃N₄-Au-CdS, ZnS-WS₂-CdS, C₃N₄-CdS and Pd-Cr₂O₃-CdS have also been discussed. Finally, the advances in the actively studied metal organic framework based photocatalysts that are emerging as effective alternate for metal oxide based photocatalysts is also discussed in detail.