Tannin chemistry enabled lignocellulose-supported Fe0: A sustainable separation material for antibiotic removal from water

Lignocellulose (LC), a distinctive biomass fibrous material, exhibits unique potential in catalysis due to its inherent structural properties and rich functional group. In this study, an efficient and environmentally friendly catalyst (LT-Fe 0 ) was successfully fabricated by immobilizing zero-valent iron (Fe 0 ) onto plant tannin-functionalized lignocellulose (LT). The as-prepared LT-Fe 0 exhibited remarkable catalytic activity toward ciprofloxacin (CIP) degradation in aqueous solutions, achieving a removal efficiency of 93.21% under optimum conditions ([C 0 ] = 50   mg L −1 , [LT-Fe 0 ] = 0.5 g L −1 , T  = 25 °C and pH = 3.0). The catalyst demonstrated effective anti-interference capability against some typical co-existing factors. Moreover, LT-Fe 0 retained 90.12% of its initial removal efficiency after six regeneration cycles. This excellent performance was attributed to the protective role of the LT matrix, which effectively reduced the agglomeration and oxidation of Fe 0 active sites. Radical quenching experiments confirmed that hydroxyl radicals (•OH) were the predominant reactive oxygen species responsible for CIP degradation. Based on density functional theory (DFT) calculations and liquid chromatography-mass spectrometry (LC-MS) analysis, possible degradation pathways of CIP over LT-Fe 0 were proposed. Furthermore, toxicological assessment revealed that the degradation process substantially reduced the toxicity of CIP and its intermediates. This work provides a novel route for lignocellulose valorization and offers a practical solution for mitigating CIP contamination in specific aquatic environments.