Impact des nanoparticules synthétisées : semi-conductrices, à faible coût et éco-respectueuses sur la remédiation de l’eau via des procédés d’oxydation avancés.

Abstract

ABSTRACT In order to investigate the structural, morphological, antibacterial, and photocatalytic capabilities of silver oxide (AgO) and zinc oxide (ZnO) nanoparticles, this work uses leaf extract as a natural reducing agent. With an emphasis on their uses in the environmental and medical domains, the study examines how the concentration of leaf extract affects the nanoparticles' characteristics. Although the concentration of the leaf extract changed the size of the crystallites and the density of defects, X-ray diffraction (XRD) examination for the synthesis of AgO nanoparticles revealed that the extract had no effect on the crystalline phase of AgO. At 2θ values of 32.83°, 38.08°, 54.95°, 65.50°, and 68.83°, respectively, diffraction peaks were detected that corresponded to the (111), (200), (220), (311), and (222) Bragg planes. Depending on the leaf extract concentration, the average crystallite size varied between 15 and 40 nm. According to scanning electron microscopy (SEM), raising the quantity of leaf extract caused the particle sizes to decrease from around 100 nm to 10 nm, but it also increased the aggregation of the particles. The existence of functional groups on both the AgO nanoparticles and the leaf extract was verified by Fourier-transform infrared spectroscopy (FTIR), which showed peaks that corresponded to hydroxyl groups, C-O bond vibrations, and metal-oxygen bond vibrations. UV-Vis spectroscopy revealed that the nanoparticles had broad absorption bands in the visible and ultraviolet spectrums, with a rise in Urbach energy (Eu) and a noticeable drop in band gap energy (Eg) when the quantity of leaf extract rose. Ag₂O nanoparticles showed strong antibacterial action against both gram-positive and gram-negative bacteria, with minimum inhibitory concentrations (MICs) between 6.25 and 25 μg/ml. However, against Candida albicans, no discernible antifungal action was seen. Methylene blue (MB) dye photocatalytic degradation revealed that Ag₂O nanoparticles made with leaf extract were less effective than as-synthesized Ag₂O, with degradation yields ranging from 68% to 87% and rate constants range from 1.32 to 4.02 × 10⁻² min⁻¹. The synthesis of ZnO nanoparticles was confirmed through X-ray diffraction (XRD) analysis, which identified a hexagonal wurtzite crystalline structure. The crystallite size and defect density were observed to be dependent on the concentration of leaf extract and the annealing temperature (320°C and 500°C). Scanning electron microscopy (SEM) images indicated that an increase in extract concentration resulted in the formation of smaller spherical nanoparticles; however, higher concentrations also contributed to increased particle aggregation. Fourier-transform infrared spectroscopy (FTIR) analysis identified functional groups analogous to those present in Ag₂O nanoparticles, including hydroxyl groups, C–O bonds, and metal–oxygen vibrations. Ultraviolet-visible (UV-Vis) spectroscopy revealed a reduction in band gap energy and an increase in Urbach energy with higher leaf extract concentrations and annealing temperatures. The ZnO nanoparticles exhibited significant antimicrobial activity against both Gram-positive and Gram-negative bacteria, as well as Candida albicans. Furthermore, photocatalytic degradation studies of methylene blue dye demonstrated an efficiency of up to 74% for ZnO samples annealed at 500°C, highlighting their potential for environmental remediation. Overall, this study underscores the efficacy of green-synthesized Ag₂O and ZnO nanoparticles as sustainable alternatives to conventional synthesis methods. The findings demonstrate their potential applications in antimicrobial treatments, water purification, and environmental catalysis. By leveraging natural resources such as leaf extracts, this research contributes to the development of eco-friendly nanotechnology, promoting enhanced material properties for diverse technological and environmental applications.

Keywords: Green synthesis; Silver oxide nanoparticles; zinc oxide nanoparticles; X-ray diffraction; Optical properties; Photocatalysis. ; antimicrobialtreatments