High-efficiency adsorption of norfloxacin using octahedral UIO-66-NH2 nanomaterials: Dynamics, thermodynamics, and mechanisms

Antibiotics abuse has been a significant threat to the environment and human health. In this study, we successfully synthesized highly stable amino-functionalized Zr-based metal-organic frameworks (UiO-66-NH2) and studied the adsorption behaviors of norfloxacin (NOR) in water. The adsorption capacities of UiO-66-NH2 reached a maximum of 222.5 mg/g for NOR, which were considerably higher than that of most reported adsorbents. Moreover, the equilibrium time (6 h) was less than that of several previously reported adsorbents. Ionic-strength-influenced experiments showed that NaCl and CaCl2 aqueous solutions could improve the removal efficiency of NOR. The presence of humic acid could barely affect the adsorption amount. At a concentration of 10 mg/L, the highest partition coefficient of 20.9 mg/g/mu M was obtained, and the removal rate of NOR was as high as 91.6%, implying that UiO-66-NH2 offered considerable adsorption performance at a low concentration of NOR. In addition, UiO-66-NH2 exhibited good regeneration efficiency, thus offering the possibility to remove norfloxacin from sewage. Finally, several credible adsorption mechanisms were proposed. The results will aid us to comprehend the surface interaction between organic micropollutants and UiO-66-NH2 and prefigure the potential of UiO-66-NH2 as a novel adsorbent for the removal of NOR.