Enhanced visible-light-responsive photodegradation of ciprofloxacin by direct Z-scheme ZnFe2O4@g-C3N4 nanocomposites

Abstract

The zinc ferrite@graphitic carbon nitride (ZnFe2O4@g-C3N4, ZFO@CN) nanocomposites were fabricated as the direct Z-scheme heterostructured photocatalysts for the enhanced visible-light-driven photodegradation of ciprofloxacin (CIP). The 15 – 30 nm ZFO, fabricated from the nonaqueous hydrothermal method, is well-distributed on the sheet-like CN structure, resulting in the high specific surface and mesoporosity with increased surface-to-volume ratio and reactive sites. Moreover, the heterojunction interface between ZFO and CN enhances the visible light response as well as decreases the electron–hole recombination, and subsequently increases the photodegradation performance of CIP over ZFO@CN. A nearly complete removal efficiency with a rate constant of 0.047 min−1 for CIP photodegradation is observed. The environmental parameters including pH, initial CIP concentration, inorganic anions and water matrices were examined to optimize the photocatalytic activity of the ZFO@CN nanocomposite. The ZFO@CN nanocomposite exhibits excellent structural and physicochemical stability and good reusability over 5 cycles. The radical trapping results signify that O2− and h+ are the primarily responsible radicals for the enhanced degradation of CIP over direct Z-scheme ZFO@CN heterojunction. Results clearly elaborate on the superiority of ZFO@CN over the photodegradation of CIP, which can serve as the platform for the fabrication of metal oxide@CN as the Z-scheme heterojunction for water and wastewater purification.