Advancements in biogenic synthesis of zinc oxide nanoparticles for superior water decontamination and antibacterial efficacy

Abstract

An urgent problem is the bacterial infestations caused by home and industrial wastes that contaminate surface water. This article presents a sustainable and affordable method for synthesizing zinc oxide nanoparticles (ZnO NPs) utilizing Asparagus racemosus root extract. X-ray diffraction, Fourier transform infrared spectroscopy, and UV–visible spectrum analysis were used to characterize the synthesized ZnO nanoparticles. The X-ray diffraction peaks of ZnO NPs matched to a standard JCPDS card (no. 36–1451) and the particles were 21–29 nm in size and had a wurtzite structure with good crystallinity. UV–Vis spectroscopy showed absorption peaks between 359 and 364 nm in ZnO NPs synthesized from Asparagus racemosus root extract. ZnO NPs were confirmed by FTIR, which revealed absorption bands in the 469–525 cm⁻¹ region, showing stretching of the Zn–O bond. In this study, methylene blue (MB) was degraded using ZnO nanoparticles as photocatalysts under the influence of UV light. Notably, the maximum MB decomposition efficiency of 98% was demonstrated by ZnO for 100 mg/mL with reaction rate constants of 0.0312, 0.02104, and 0.001362 min⁻¹ for ASP₁, ASP₂, and ASP₃, respectively. Additionally, the well diffusion technique was used to assess the zone of inhibition, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of ZnO nanoparticles against clinical strains of Escherichia coli and Staphylococcus aureus. ZnO-NPs were more effective against E. coli and S. aureus which exhibited inhibition zones of 13 ± 0.57 and 15 ± 1.15 mm, respectively. These results emphasize the important potential of ZnO nanoparticles produced from biological sources for effective water purification, emphasizing their photocatalytic and antibacterial capabilities.

Graphical Abstract