Enhanced Visible-Light-Responsive Photocatalytic Degradation of Ciprofloxacin by the CuxO/Metal-Organic Framework Hybrid Nanocomposite

Abstract

Ciprofloxacin (CIP) is a commonly used antibiotic, however, once in the environment, it is highly toxic with a poor biodegradability. Given these attributes, an effective strategy for the removal of CIP is urgently needed for the protection of water resources. Herein, a novel copper metal-organic framework (CuxO/MOF) multifunctional material has been produced, in this work, by the calcination of Cu-MOF urea at 300 °C, in the presence of a 5% H2 atmosphere. The morphological, structural, and thermal properties of the prepared CuxO/MOF were determined through various techniques, and its photocatalytic behavior was investigated for the degradation of CIP under visible-light irradiation. The prepared CuxO/MOF bifunctional material is presented as a graphitic carbon-layered structure with a particle size of 9.2 ± 2.1 nm. The existence of CuO-Cu2O-C, which was found on the CuxO/MOF surface, enhanced the adsorption efficiency and increased the photosensitivity of CuxO/MOF, towards the degradation of CIP in aqueous solutions. The tailored CuxO/MOF, not only shows an excellent CIP degradation efficiency of up to 92% with a constant kinetic rate (kobs) of 0.048 min−1 under visible light, but it can also retain the stable photodegradation efficiency of >85%, for at least six cycles. In addition, CuxO/MOF has an excellent adsorption capacity at pH 6.0 of the maximum Langmuir adsorption capacity of 34.5 mg g−1 for CIP. The results obtained in this study demonstrate that CuxO/MOF is a reliable integrated material and serves as an adsorbent and photocatalyst, which can open a new pathway for the preparation of visible-light-responsive photocatalysts, for the removal of antibiotics and other emerging pollutants.

Recent advances in Cu-BTC MOF-based engineered materials for the photocatalytic treatment of pharmaceutical wastewater towards environmental remediation

“…Tsai et al successfully designed a bifunctional Cu x O/MOF in the presence of urea for the photocatalytic degradation of CIP under visible light in an aqueous medium. 43 This could serve as a potential and reliable candidate for establishing a new pathway for the advancement of visible-light-responsive photocatalysts to eliminate antibiotics and other emerging contaminants.…”

Mixed valence copper oxide composites derived from metal–organic frameworks for efficient visible light fuel denitrification

“…The two characteristic peaks at 952.5 and 932.8 eV correspond to the binding energies of Cu + 2p 1/2 and 2p 3/2 electrons, while the two characteristic peaks at 953.8 and 933.8 eV correspond to the binding energies of Cu 2+ 2p 1/2 and 2p 3/2 , respectively. 46,47 In addition, satellite peaks with 2p 1/2 and 2p 3/2 peaks were also observed, corresponding to the electronic oscillation, 48 indicating the presence of Cu 2+ and the coexistence of Cu 2 O and CuO on Cu x O-T. It can be found that in Cu x O-T, the ratio of Cu + /Cu 2+ gradually decreases with the increase in temperature, and the ratio of Cu x O-300 is the highest at other temperatures, while Cu x O-500 is the lowest.…”