Photocatalytic degradation of microcystin-LR by modified TiO2 photocatalysis: A review

Microcystin-LR (MC-LR), the most toxic and commonly encountered cyanotoxin, is produced by harmful cyanobacterial blooms and potentially threatens human and ecosystems health. Titanium dioxide (TiO2) photocatalysis is attracting growing attention and has been considered as an efficient, environmentally friendly and promising solution to eliminate MC-LR in the aquatic ecosystems. Over recent decades, scientific efforts have been directed towards the understanding of fundamentals, modification strategies, and application potentials of TiO2 photocatalysis in degrading MC-LR. In this article, recent reports have been reviewed and progress has been summarized in the development of heterogeneous TiO2-based photocatalysts for MC-LR photodegradation under visible, UV, or solar light. The proposed photocatalytic principles of TiO2 and destruction of MC-LR have been thoroughly discussed. Specifically, some main modification methods for improving the drawbacks and performance of TiO2 nanoparticle were highlighted, including element doping, semiconductor coupling, immobilization, floatability amelioration and magnetic separation. Moreover, the performance evaluation metrics quantum yield (QY) and figure of merit (FOM) were used to compare different photocatalysts in MC-LR degradation. The best performance was seen in N-TiO2 with QY and FOM values of 2.20E−07 molecules/photon and 1.00E−11 mol·L/(g·J·h). N-TiO2 or N-TiO2-based materials may be excellent options for photocatalyst design in terms of MC-LR degradation. Finally, a summary of the remaining challenges and perspectives on new tendencies in this exciting frontier and still an emerging area of research were addressed accordingly. Overall, the present review will offer a deep insight for understanding the photodegradation of MC-LR with modified TiO2 to further inspire researchers that work in associated fields. [Display omitted] •Microcystin-LR represents one of the most toxic water pollutants.•The research of modified TiO2 for microcystin-LR removal was reviewed.•The mechanisms of microcystin-LR photodegradation were summarized.•Focuses on approaches for improving TiO2 were also discussed.•Research goals were suggested for further development.