Velu Subash, Velu Manikandan, Thamaraiselvi Kanagaraj, Duraisamy Elango, Ponnuchamy Kumar, Palaniyappan Jayanthi, Kwang Soup Song
This study presents the synthesis and characterisation of ZnFe 2 O 4 and ZrO x -modified ZnFe 2 O 4 (1–3 wt%) nanocomposites via co-precipitation and wet impregnation for visible-light-driven, H 2 O 2 -assisted photo-Fenton degradation of antibiotics. Structural analysis confirmed a cubic spinel phase, while ZrO x incorporation induced a hierarchical sea urchin-like morphology, enhancing surface area, charge carrier separation, and electron mobility. Among the prepared materials, the 2 wt% ZrO x /ZnFe 2 O 4 nanocomposite exhibited the highest photocatalytic performance, achieving 93.4% and 97.6% removal of ciprofloxacin (CIP) and tetracycline hydrochloride (TCH), respectively, within 140 and 120 min. Radical scavenging experiments identified hydroxyl (•OH) and superoxide (•O₂⁻) species as the dominant reactive oxygen species (ROS), supporting a photo-Fenton mechanism. Electrochemical analyses revealed n-type semiconducting behaviour and a conduction band potential of − 0.513 V vs. NHE, favouring redox reactions. Density functional theory (DFT) calculations provided insight into band structure modifications and highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) transitions, correlating with improved charge transfer. The photocatalyst demonstrated excellent recyclability (~ 90% activity retention) and low cytotoxicity (> 92% HEK-293 cell viability), underscoring its environmental and biological safety. These findings highlight the structure–function relationship and interfacial synergy in ZrO x /ZnFe 2 O 4 nanocomposites, demonstrating their potential as sustainable materials for antibiotic removal from water.