Selective production of singlet oxygen for harmful cyanobacteria inactivation and cyanotoxins degradation: Efficiency and mechanisms

Knowledge about the impact of singlet oxygen ( 1 O 2 ) on the characteristics and inactivation of harmful cyanobacterial organic matter is limited. In this study, the feasibility of using an improved single-iron doped graphite-like phase carbon nitride catalyst (FeCN) to activate peroxymonosulfate (PMS) catalytic production of 1 O 2 to inactivate four harmful cyanobacteria was investigated. The inactivation efficiencies at 30 min were 92.77%, 66.84%, 91.06%, and 93.45% for Microcystis aeruginosa ( M. aeruginosa ), Nodularia harveyana , Oscillatoria sp., and Nostoc sp . , respectively. This was associated with adjusting experimental parameters, such as the FeCN and PMS doses and initial pH, to obtain the maximum 1 O 2 yield. The quenching experiment results and electron paramagnetic resonance spectra showed that 1 O 2 generated via the non-radical pathway might play a dominant role in inactivating harmful cyanobacteria and degrading harmful algal toxins (Microcystin-LR and Nodularin). In addition, the FeCN-PMS system not only effectively destroyed the integrity of harmful cyanobacterial cells but also effectively degraded cyanobacterial toxins , thereby preventing severe secondary contamination by cell rupture. A possible removal mechanism was proposed. This reveals the potential of 1 O 2 to simultaneously inactivate harmful cyanobacteria and degrade harmful cyanobacterial toxins.