Photocatalytic generation of electron and hole for peroxymonosulfate activation to degrade levofloxacin over ZnO/ZnFe2O4 heterojunction

This study addresses the challenge of eliminating persistent antibiotics like levofloxacin (LEV) from wastewater by developing a ZnO/ZnFe 2 O 4 heterojunction catalyst through a sol-gel method. The heterojunction synergistically combines ZnO and ZnFe 2 O 4 to reduce bandgap energy (1.89–1.99   eV) and enhance visible-light absorption. Under energy-efficient LED irradiation (5   W, 320–780   nm), the ZnO/ZnFe 2 O 4 -PMS system achieved 94.11% LEV degradation within 90   min, alongside 58.61% total organic carbon removal efficiency and 71.69% defluorination efficiency, outperforming individual components and physical mixtures. Mechanistic investigations revealed that reactive oxygen species ( 1 O 2 , SO 4 - ∙, ‧O 2 - and ‧OH) and holes jointly oxidize LEV. The heterojunction’s built-in electric field effectively suppressed charge recombination, as being confirmed by photoluminescence and photocurrent analyses. Remarkably, the catalyst retained >87% efficiency over four cycles with negligible metal leaching efficiency (<1%), demonstrating robust stability. This work highlights the dual advantages of the ZnO/ZnFe 2 O 4 heterojunction and LED-driven activation, offering a scalable and energy-efficient strategy for antibiotic wastewater remediation.