Synchronous removal of oxytetracycline and Cr(Ⅵ) in Fenton-like photocatalysis process driven by MnFe2O4/g-C3N4: Performance and mechanisms

Abstract

Complex wastewater has more complicated toxicity and potential harm to organisms, and synchronous REDOX of complex pollutants in wastewater has always been a bottleneck in the development of advanced oxidation technology. Herein, a Fenton-like photocatalytic system (MnFe₂O₄/g-C₃N₄ heterojunction composites) was established to simultaneously remove oxytetracycline (OTC) and Cr(Ⅵ) in this study. The MnFe₂O₄/g-C₃N₄ heterojunction composites exhibited outstanding catalytic performances for OTC and Cr(Ⅵ) removal, and more than 90% of OTC and nearly 100% of Cr(Ⅵ) were simultaneously removed within 1 min photocatalysis. The photo-generared electrons and holes played significant roles in Cr(Ⅵ) reduction and OTC degradation, respectively. Moreover, the heterojunction formed between g-C₃N₄ and MnFe₂O₄ effectively accelerated the separation and migration of photogenerated carriers. The OTC degradation was mainly initiated by cracking of benzene rings, degradation of substituents, and removal of groups such as -OH, -NH₂, -CH₃, and -CONH₂, resulting in generation of small molecular substances; Cr(Ⅲ) was the main reduction product of Cr(Ⅵ). Meanwhile, the MnFe₂O₄/g-C₃N₄ heterojunction composites also exhibited excellent stability and reusability in removal of OTC and Cr(Ⅵ).

Keywords: Cr(Ⅵ); MnFe(2)O(4); Oxytetracycline; Photocatalysis; g-C(3)N(4).