Decoration of CeO₂ nanoparticles on g-C₃N₄ for degradation of microcystins through photocatalytic activation of peroxymonosulfate

As the most common cyanobacterial toxin, microcystin LR (MC-LR) has dangerous neurotoxicity and hepatotoxicity, posing a serious threat to human and ecosystem health. Therefore, we constructed a type-II CeO₂/g-C₃N₄ heterojunction for highly efficient degradation of MC-LR via peroxymonosulfate (PMS) assisted-visible light-driven photocatalysis process. Multi techniques were conducted to analyze the microstructures, optical and electrochemical properties of CeO₂/g-C₃N₄. The experimental results indicate that the composite material has appropriate energy levels and establishes a well-established interfacial band structure, facilitating the migration and separation of photogenerated electron-hole pairs. The coupled photocatalysis and PMS activation system presented a dramatically enhanced catalytic performance. Within 60 min, 10% CeO₂/g-C₃N₄/PMS could degrade 99% of the MC-LR present in the solution under visible light irradiation, which was about 3.8 times higher than that in a single photocatalytic system. The optimal conditions for this degradation process were a PMS dosage of 3.0 mM and an initial pH of 2.5. EPR analysis revealed that SO₄^•ˉ, O₂^•ˉ, h⁺, and ¹O₂ were involved in the degradation process. Moreover, the intermediates of its degradation were analyzed through UPLC-MS. This study provides a valuable resource for the intelligent development of type-II heterojunction and its practical implications in the photodegradation of MC-LR through synergistic activation with PMS.