Enhanced visible-light photodegradation of fluoroquinolone-based antibiotics and E. coli growth inhibition using Ag-TiO2 nanoparticles

Jiao Wang; Ladislav Svoboda; Zuzana Němečková; Massimo Sgarzi; Jiří Henych; Nadia Licciardello; Gianaurelio Cuniberti

doi:10.1039/d0ra10403e

Enhanced visible-light photodegradation of fluoroquinolone-based antibiotics and E. coli growth inhibition using Ag-TiO₂ nanoparticles

RSC Adv. 2021 Apr 13;11(23):13980-13991. doi: 10.1039/d0ra10403e.

Authors

Jiao Wang¹, Ladislav Svoboda^{2

3}, Zuzana Němečková⁴, Massimo Sgarzi¹, Jiří Henych⁴, Nadia Licciardello¹, Gianaurelio Cuniberti¹

Affiliations

¹ Institute for Materials Science, Max Bergmann Centre of Biomaterials, Dresden Center for Nanoanalysis, TU Dresden 01062 Dresden Germany nadia.licciardello@tu-dresden.de nadia.licciardello@inl.int gianaurelio.cuniberti@tu-dresden.de.
² IT4Innovations, VŠB - Technical University of Ostrava 17. listopadu 15/2172 708 33 Ostrava Czech Republic.
³ Nanotechnology Centre, CEET, VSB-Technical University of Ostrava 17. listopadu 15/2172 708 33 Ostrava Czech Republic.
⁴ Institute of Inorganic Chemistry, Czech Academy of Sciences Husinec-Řež 1001 250 68 Řež Czech Republic.

Abstract

Antibiotics in wastewater represent a growing and worrying menace for environmental and human health fostering the spread of antimicrobial resistance. Titanium dioxide (TiO₂) is a well-studied and well-performing photocatalyst for wastewater treatment. However, it presents drawbacks linked with the high energy needed for its activation and the fast electron-hole pair recombination. In this work, TiO₂ nanoparticles were decorated with Ag nanoparticles by a facile photochemical reduction method to obtain an increased photocatalytic response under visible light. Although similar materials have been reported, we advanced this field by performing a study of the photocatalytic mechanism for Ag-TiO₂ nanoparticles (Ag-TiO₂ NPs) under visible light taking in consideration also the rutile phase of the TiO₂ nanoparticles. Moreover, we examined the Ag-TiO₂ NPs photocatalytic performance against two antibiotics from the same family. The obtained Ag-TiO₂ NPs were fully characterised. The results showed that Ag NPs (average size: 23.9 ± 18.3 nm) were homogeneously dispersed on the TiO₂ surface and the photo-response of the Ag-TiO₂ NPs was greatly enhanced in the visible light region when compared to TiO₂ P25. Hence, the obtained Ag-TiO₂ NPs showed excellent photocatalytic degradation efficiency towards the two fluoroquinolone-based antibiotics ciprofloxacin (92%) and norfloxacin (94%) after 240 min of visible light irradiation, demonstrating a possible application of these particles in wastewater treatment. In addition, it was also proved that, after five Ag-TiO₂ NPs re-utilisations in consecutive ciprofloxacin photodegradation reactions, only a photocatalytic efficiency drop of 8% was observed. Scavengers experiments demonstrated that the photocatalytic mechanism of ciprofloxacin degradation in the presence of Ag-TiO₂ NPs is mainly driven by holes and ˙OH radicals, and that the rutile phase in the system plays a crucial role. Finally, Ag-TiO₂ NPs showed also antibacterial activity towards Escherichia coli (E. coli) opening the avenue for a possible use of this material in hospital wastewater treatment.