Effective visible light driven photocatalytic degradation of tetracycline and ciprofloxacin with enhanced heteroaromatic structures and bioaccumulation studies

Abstract

Antibiotics are emerging pharmaceutical pollutants that significantly contribute to the development of antimicrobial resistance. Among them, broad-spectrum antibiotics like tetracycline (TC) and ciprofloxacin (CP) are of particular concern due to their persistence and tendency to bioaccumulate. To overcome this challenge, we developed a series of novel visible-light-active photocatalytic composites (C1-C4), constructed from a titanium-iron (Ti-Fe) bimetallic complex coordinated with pyridine dicarboxylic acid (PDA) as a tridentate organic linker. This composite exhibited a reduced band gap of 1.57 eV, enhancing its photocatalytic activity under visible light. Photocatalytic degradation studies revealed that the composite achieved 89% degradation of TC within 30 min and 72% degradation of CP within 10 min of visible light irradiation. The treated water met pharmaceutical wastewater discharge standards, confirming the catalyst's effectiveness. The catalyst's environmental stability was evaluated through leaching studies in simulated ocean water, indicating minimal release of toxic components and confirming its environmental safety. Furthermore, bioaccumulation studies in tomato plants (Solanum lycopersicum) showed that TC and CP followed the accumulation order: root (0.59194 mg/g) > shoot (0.48821 mg/g) > leaf (0.03151 mg/g), and for CP leaf (0.0053 mg/g) > shoot (0.0044 mg/g) > root (0.0040) The fruit was also tested estimating amount of TC and CP as 0.012 mg/g &0.033 mg/g respectively emphasising the importance of removing antibiotic residues from water sources.