Surface engineering of Al₂O₃ nanotubes by ureasolysis method for activating persulfate degradation of antibiotics

Though ecofriendly, pure Al₂O₃ has never been used for activation of peroxodisulfate (PDS) to degrade pollutants. We report the fabrication of Al₂O₃ nanotubes by ureasolysis method for efficient activating PDS degradation of antibiotics. The fast ureasolysis in aqueous AlCl₃ solution produces NH₄Al(OH)₂CO₃ nanotubes, which are calcined to porous Al₂O₃ nanotubes, and the release of ammonia and carbon dioxide engineers the surface features of large surface area, numerous acidic-basic sites and suitable Zeta potentials. The synergy of these features facilitates the adsorption of the typical antibiotics ciprofloxacin and PDS activation, which is proved by experiment results and density functional theory simulation. The proposed Al₂O₃ nanotubes can catalyze 92-96% degradation of 10 ppm ciprofloxacin within 40 min, with chemical oxygen demand removal of 65-66% in aqueous, and 40-47% in whole including aqueous and catalysts. Ciprofloxacin at high concentration, other fluoroquinolones and tetracycline can also be effectively degraded. These data demonstrate the Al₂O₃ nanotubes prepared by the nature-inspired ureasolysis method has unique features and great potentials for antibiotics degradation.