Enhanced visible-light photocatalytic activity and antibacterial behaviour on fluorine and graphene synergistically modified TiO₂ nanocomposite for wastewater treatment

ABSTRACT

The photocatalytic reduction of methylene blue was recognized as an economical and effective way for dye removal. To enhance photocatalytic activity under visible-light condition, fluorine and graphene synergistically modified TiO₂ (F-TiO₂/rGO) nanocomposites were successfully prepared by sol–gel method. Characterization results showed F ions played an essential role in the formation of TiO₂ nanoparticles. Between the fluorine sources selected, NH₄F was more optimal than NaF doping on the grounds that the existence of Na⁺ ion was an inevitable factor for the production of brookite. F-TiO₂/rGO nanocomposite obtained by adding 5%at NH₄F significantly narrowed the bandgap energy from approximately 3.17 to 2.41 eV. Box–Behnken design was adopted to optimize the MB photo-degradation process by F_(5%NH4F)-TiO₂/rGO nanocomposites under different reaction conditions. Moreover, the antibacterial behaviour of this novel material was also investigated by Escherichia coli (E. coli) bacteria under visible light. The morphology changes of E. coli cells were directly observed by field emission scanning electron microscope and further confirmed that the excellent sterilization of F-TiO₂/rGO nanocomposites resulted from the active species. The outstanding photocatalytic performance and antibacterial behaviour of F-TiO₂/rGO nanocomposite was attributed to the synergistic effect of photocatalytic redox reaction and adsorption. These results indicated F_(5%NH4F)-TiO₂/rGO nanocomposite was a promising antibacterial photo-adsorbent for wastewater treatment improvement.

GRAPHICAL ABSTRACT

KEYWORDS:

• Modified TiO₂
• fluorine and graphene
• wastewater treatment
• photocatalytic degradation
• antibacterial behaviour

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article.

Additional information

Funding

The financial supports from the National Natural Science Foundation of China [Grant Number 50576071] was gratefully acknowledged.