Bio-based TEMPO-CNC reinforced Fe-doped UiO-66 with hierarchical porosity for efficient enrofloxacin removal.

Enrofloxacin (ENR), characterized by its remarkable stability and resistance to degradation, has become a significant contaminant in aquatic ecosystems. In this study, a CNC/UiO-66(Fe) composite was synthesized via a one-step hydrothermal method, and response surface methodology (RSM) was employed to optimize the key experimental conditions for the efficient removal of ENR from aqueous solutions. The incorporation of cellulose nanocrystals (CNC) improved the dispersibility and stability of UiO-66, and significantly enhanced the crystallinity of the material, as confirmed by XRD analysis. Iron (Fe) doping introduced additional active sites and defects, synergistically enhancing the overall adsorption capacity. The composite exhibited a high BET surface area of 1294.81 m2/g and a well-developed porous structure. The adsorption process was spontaneous and exothermic, fitting well with both the pseudo-second-order kinetic model and the Langmuir isotherm model. Under alkaline conditions, the material showed excellent adsorption performance, with a theoretical maximum adsorption capacity of 275.84 mg/g for ENR at 25 °C and pH 10. The adsorption mechanism involved multiple synergistic interactions, including electrostatic attraction, hydrogen bonding, π-π stacking, metal coordination, and pore filling. Furthermore, CNC/UiO-66(Fe) exhibited excellent stability and reusability, retaining over 80 % of its removal efficiency after five cycles. This study provides an effective and sustainable approach for remediating antibiotic contaminants in aquatic environments.