Aqueous norfloxacin removal by novel biochar adsorbent prepared through ethanol-combined ball milling

Ethanol combined-ball milling was used to modify corn-stover biochar. The adsorption performance and mechanisms of aqueous norfloxacin (NOR) onto the resulting biochar (C₂H₆O-BC) were evaluated. Ball-milling modulated its surface oxygen-containing functional groups and enhanced its specific surface area. The adsorption capacity of C₂H₆O-BC was 163 mg·g⁻¹, and about 72% of the equilibrium adsorption capacity could be reached within 60 min. The electrostatic interaction was not the dominant mechanism when initial pH was lower than 8.00. The antagonistic effect of Cu(II) on NOR adsorption was observed. The fixed-bed column adsorption showed its potential to remove NOR and Cu(II) spontaneously. Sequential two-stage batch reaction experiment showed that it was a fast and efficient technology to remove NOR using C₂H₆O-BC. The adsorption mechanisms were suggested as π-π interactions, H-bonding and pore-filling. In summary, ethanol-combined ball milling in this study provided an efficient adsorbent for NOR.