Copper oxide combing with multi-walled carbon nanotubes activated peroxyacetic acid for the degradation of sulfamethoxazole

In this study, a stable and efficient catalyst, copper oxide composite multi-walled carbon nanotubes (CuxO@MWCNTs), was prepared by a sol-gel method for the activation of peracetic acid (PAA) for the degradation of sulfamethoxazole (SMX) in water. The catalyst exhibited excellent adsorption properties, and the MWCNTs promoted electron transfer between Cu+/Cu2+ and formed a synergistic catalytic effect for rapid activation of PAA to generate reactants with a wide pH applicability. Under the condition of PAA concentration of 0.1 mM, SMX dosage of 1.5 mg·L−1, catalyst concentration of 200 mg·L−1, pH = 7, and reaction temperature of 25 °C, the complete degradation of SMX was achieved in the CuxO@MWCNTs/PAA system within 16 min. The reaction mechanism of the CuxO@MWCNTs/PAA system was systematically investigated through quenching experiments, electron spin resonance spectra, and the result of X-ray photoelectron spectroscopy. Radical and non-radical pathways were determined, and unlike most of previous studies, singlet oxygen (non-radical pathway) was the main reactive species for SMX degradation in this study. In addition, CuxO@MWCNTs maintained good activity and stability. This study provided a green and efficient technique for removing antibiotics from water and offered new ideas for application in environmental remediation.