Efficient Oxidation of Paracetamol Triggered by Molecular-Oxygen Activation at β-Cyclodextrin-Modified Titanate Nanotubes

Titanate nanotubes (TNTs) were coated with a cyclic oligosaccharide (carboxymethyl-beta-cyclodextrin, CM-beta-CD) to obtain a photocatalyst (CM-beta-CD-TNT) for efficiently activating molecular oxygen and removing the target contaminant. The hydrophobic cavity and the large specific surface area of the photocatalyst provide abundant active sites for activating molecular oxygen. The free radical capture experiment and quenching experiment showed that cyclodextrin could facilitate adsorption and activation of molecular oxygen to produce O-2(.-). Therefore, compared with the pristine TNT, CM-beta-CD-TNT accelerated the oxidation efficiency of paracetamol (APAP) by 3.4 times. Moreover, the ring cleavage reaction induced by CM-beta-CD-TNT effectively reduced the acute toxicity of wastewater containing APAP. Furthermore, 100% of bisphenol A (BPA), bisphenol S (BPS), phenol, 2,4-dichlorophen (2,4-DCP), and carbamazepine (CBZ) were degraded by CM-beta-CD-TNT after 2.5 h ultraviolet (UV) light irradiation. This strategy provides a new dimension for the advanced treatment of organic wastewater by organic macrocyclic molecule-modified materials.