Controlling the pathogenic bacterial growth and wastewater treatment by biogenic ZnO nanoparticles synthesized using Nyctanthes arbor-tristis flower extract

This report describes the synthesis of biogenic ZnO nanocatalyst, and nano antibiotics using Nyctanthes arbor-tristis (N. arbor-tristis) flower extract for the first time. The flower extract itself showed significant inhibition zones against bacterial strains and enhancement of inhibition zone was recorded for the extract mediated ZnO NPs. Moreover, ZnO NPs revealed excellent photocatalytic performances by degradation of organic dye under irradiation of UV light. The zincite phase of ZnO NPs was probed by X-ray diffraction (XRD) analysis, and the average crystallite size was 19.35 nm with a dislocation density of 2.67 × 10 − 3 nm −2 . The bio-reduction of ZnO NPs was confirmed by UV–visible spectroscopy with a narrow sharp peak at a wavelength of 375 nm for the corresponding bandgap 2.81 eV. The morphological analysis was conducted by Field Emission Scanning Electron Microscopy (FESEM) and the average particle size was calculated 44.93 nm. Fourier Transform Infrared Spectroscopy (FTIR) has been used to identify the active functional groups in N. arbor-tristis flower extract. The antibacterial activities of biogenic ZnO NPs have been utilized against Escherichia coli 25922 ( E. coli ) and Staphylococcus aureus 398 ( S. aureus ) pathogens in different dose concentrations. ZnO NPs exhibited remarkable inhibition zones in a low concentration, and the inhibition zones had increased for higher dose concentrations. Moreover, the ZnO nanocatalyst exhibited tremendous photocatalytic performance by degradation of 88.4 % Methylene blue (MB) dye with a degradation rate of 0.0156 min −1 . These promising findings may serve as noteworthy documentation for the treatment of water pollution and the development of pharmaceutical applications. • Nyctanthes arbor-tristis flower extract has been used to synthesize ZnO NPs. • Comparative antibacterial activities among different concentrations of ZnO NPs and commercial antibiotic have been evaluated. • Nyctanthes arbor-tristis flower extract exhibits potential activities against bacterial strains. • Biogenic ZnO NPs revealed excellent antibacterial activities against both gram-positive and negative pathogens. • ZnO NPs played as potential catalyst to remove the pollutants from the wastewater.