A review on the potential of photocatalysis in combatting SARS-CoV-2 in wastewater

Abstract

Photocatalytic technology offers powerful virus disinfection in wastewater via oxidative capability with minimum harmful by-products generation. This review paper aims to provide state-of-the-art photocatalytic technology in battling transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in wastewater. Prior to that, the advantages and limitations of the existing conventional and advanced oxidation processes for virus disinfection in water systems were thoroughly examined. A wide spectrum of virus degradation by various photocatalysts was then considered to understand the potential mechanism for deactivating this deadly virus. The challenges and future perspectives were comprehensively discussed at the end of this review describing the limitations of current photocatalytic technology and suggesting a realistic outlook on advanced photocatalytic technology as a potential solution in dealing with similar upcoming pandemics. The major finding of this review including discovery of a vision on the possible photocatalytic approaches that have been proven to be outstanding against other viruses and subsequently combatting SARS-CoV-2 in wastewater. This review intends to deliver insightful information and discussion on the potential of photocatalysis in battling COVID-19 transmission through wastewater.

Keywords: COVID-19; Photocatalysis; SARS-CoV-2; Virus; Wastewater.

Graphical abstract

Fig. 1

Schematic diagram of COVID-19 virus structure [4].

Fig. 2

Classification of water disinfection methods.

Fig. 3

Progress in photocatalysis in battling virus from the water system. Reproduced with permission from Elsevier, [64].

Fig. 4

(a) Schematic illustration on immobilization of fullerene on PS or SiO₂ and SEM images of (b) neat PS resin, (c) C₆₀ coated on PS resin, (d) neat SiO₂ gel and (e) C₆₀ coated on SiO₂ gel [80].

Fig. 5

(a) Images of MS2 plaques formation before and after photocatalytic disinfection by g-C₃N₄ under visible light irradiation, (b) comparison of photocatalytic performance on MS2 inactivation under visible light irradiation, (c) schematic diagram of proposed mechanism on MS2 inactivation by g-C₃N₄ photocatalyst [78].

Fig. 6

Virus inactivation process through photocatalysis [95].

Fig. 7

Schematic illustration of the proposed mechanisms of microbial disinfection by difference semiconductor photocatalysts through activation of semiconductor by visible light, then generation of ROS by various semiconductors followed by the release of metal ions targets generic materials like mRNA, deoxyribonucleic acid (DNA), and ribosomes (The blue color arrow indicates targets of bismuth vanadate, BiVO₄. The green color arrow indicates targets of Ag nanoparticle) [96].

Fig. 8

Schematic diagram of the disinfection of E. coli by photoactivation of TiO₂ photocatalyst; (a) before disinfection, (b) ROS attack results in damage of the outer membrane cell wall, (c) prolonged ROS attack results in degradation of peptidoglycan, cytoplasmic membrane and direct DNA damage [97].

Fig. 9

(a) Photocatalysis activity of Cu-TiO₂ nanofibers in single virus system and virus/bacteria mixed system, (b) photocatalytic performance under visible light irradiation, and (c) photocatalytic performance without light irradiation [75].