Photodegradation of oxytetracycline hydrochloride by Z-scheme g-C3N4 @MIL-101(Fe) heterojunction: Experimental optimization, mechanism evaluation and practical application

The residues of oxytetracycline hydrochloride (OTC) in water have potential adverse effects on human health and ecological environment. Photocatalytic degradation has been widely studied in the treatment of antibiotic pollution due to its environmentally friendly and efficient characteristics. However, the band gap of traditional photocatalysts is too wide, and the recombination of photogenerated electrons and holes is serious, which has negative effects on photocatalysis. Therefore, the Z-scheme heterojunction g-C3N4@MIL-101(Fe) composite photocatalyst was synthesized by high temperature calcination combined with solvothermal method. g-C3N4@MIL-101(Fe) was characterized by XRD, FTIR, SEM, TEM and other tests. All the results showed that the compound was successful A series of photoelectric tests showed that g-C3N4@MIL-101(Fe) has a narrower band gap, stronger light absorption ability, and improved the separation rate of photogenerated electrons and holes. Under visible light irradiation, g-C3N4@MIL-101(Fe) could remove 87.68% of OTC in 300 min. g-C3N4 @MIL-101(Fe) showed good potential for practical application in five real water samples and stability after six cycles. Finally, superoxide radicals and hole radicals were identified as the main reactive species in the photodegradation process. The mechanism and pathway of the photocatalytic degradation of OTC by g-C3N4@MIL-101(Fe) are proposed. This work expands the construction and application of Fe-MOF based Z-scheme heterostructure and provides a new idea for water pollution remediation.