Novel 2D/3D Z-scheme heterojunction with Bi12O15Cl6 nanoplates anchored on MIL-53 (Fe) derived Fe2O3@C micro-rods for enhanced visible-light-mediated photocatalytic degradation of fluoroquinolones in wastewater

Abstract

Antibiotics, ubiquitous in environmental matrices, evade conventional wastewater treatment systems, posing a threat to humans and aquatic biota. In this context, a novel 2D/3D Z-scheme Bi₁₂O₁₅Cl₆/Fe₂O₃@C (BFC) heterojunction photocatalyst was prepared by anchoring Bi₁₂O₁₅Cl₆ nanoplates on perforated Fe₂O₃@C micro-rods via solvothermal route followed by calcination. The carbon framework surrounding Fe₂O₃ led to the partial surface metallization of Bi₁₂O₁₅Cl₆ nanoplates, which proved beneficial for photoinduced charge separation. The treatment efficacy of the as-prepared materials was assessed by degrading a mixture of fluoroquinolone-based antibiotics (levofloxacin (LEV) and ciprofloxacin (CIP)) under visible light. Under optimal conditions, the degradation efficiencies of the photocatalyst for LEV and CIP reached around 96% and 91%, respectively, after 120 min. This could be related to the decreased recombination rate of photoinduced charge carriers and their enhanced separation efficacy. In addition, ^●OH radicals were determined to be the principal reactive species supporting photocatalytic degradation of LEV and CIP, followed by $O_2^{·-}$ and h⁺. The BFC photocatalyst demonstrated exceptional chemical stability, non-toxicity, and sustained photocatalytic activity across multiple cycles of reuse. Furthermore, the colony forming unit (CFU) assay performed on E. coli, along with the in silico toxicity prediction of transformation products (TPs), showed that the treated effluent and TPs exhibited lower toxicity compared to the parent compounds, respectively.