Sustainable synthesis of ZnO nanoparticles from Brickellia cavanillesii extract with enhanced photocatalytic and antimicrobial properties

Abstract

Zinc oxide (ZnO) semiconductor nanoparticles (NPs) were synthesized via a green chemistry approach using a phytochemical-rich natural extract derived from Brickellia cavanillesii in an environmentally friendly approach. Multiple techniques were used to study the properties of the obtained materials, including Scanning Electron Microscopy (SEM) to investigate surface morphology. At the same time, Transmission Electron Microscopy (TEM) was utilized to measure morphological characteristics and estimate the average particle size of the obtained materials; the analysis results suggest a direct influence of the extract and its concentration on particle size. The synthesized NPs presented high crystallinity and a zincite hexagonal shape, as analyzed employing X-ray diffraction (XRD). The photocatalytic performance of the NPs was systematically analyzed by monitoring the photodegradation of a series of organic dye pollutants under ultraviolet (UV) irradiation. The selected dyes: Congo red, methylene blue, malachite green, rhodamine B, and methyl orange, served as representative models for both anionic and cationic contaminants commonly found in industrial wastewater. The results demonstrated a remarkable capability of the materials to remove these pollutants from aqueous solutions, achieving complete degradation (100%) of Congo red and methylene blue. Furthermore, the synthesized NPs were able to eliminate at least 81% of malachite green, rhodamine B, and methyl orange, highlighting their strong potential for application in wastewater treatment and environmental remediation. Finally, the antimicrobial activity of NPs against multiple bacteria (Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae, and Escherichia coli) was analyzed, demonstrating a bacteriostatic effect on the bacteria.