Novel millimeter-sized honeycomb-like Fe/FeC@HBC from waste cotton textiles towards rapid degradation of ofloxacin via activation of HO.

Although multiphase catalysts with large sizes exhibit excellent recyclability and low toxicity in heterogeneous Fenton reactions, their reactivity, reusability and storage stability for degradation of organic contaminants still need improvement, which is essential for treating complex wastewater and ensuring environmental sustainability. In this study, the waste cotton textiles were firstly used as the carbon source to generate a novel millimeter-sized catalyst (Fe/FeC@HBC) with a honeycomb-like structure, which could effectively activate HO to realize rapid removal of ofloxacin (OFL) (100% in 10 min). It achieved remarkable removal performance across a broad temperature range (4-40 °C) and high-concentration OFL. It even demonstrated excellent removal towards other typical contaminants (Tetracycline, Ciprofloxacin, Methylene Blue, Rhodamine B, Malachite Green), showing outstanding storage stability, physical structural stability, reusability and separation characteristics. Whereafter, its removal mechanism was also explored, showing that it was entirely dependent on the degradation by the reactive oxygen species (ROS), including OH, O and O, as well as the persistent free radicals from the catalyst. Moreover, the honeycomb-like structure promoted the effective utilization of HO, facilitated the generation of OH and expedited the accumulation of OFL on the catalyst surface. Fe/FeC (inside of the catalytic instead of in the reaction solution) was essential for the degradation. Finally, the OFL degradation pathways and toxicity predictions were also proposed. Overall, this innovation supports cleaner water resources and enhances public health, demonstrating a significant step forward in environmental remediation technologies.