This study investigates the eco-friendly synthesis of zinc oxide nanoparticles (ZnO NPs) utilizing an aqueous solution of Hibiscus sabdariffa L. flower extract, which is acts as reducing agent as well as capping agent. The Fourier transform infrared spectroscopy (FTIR) results revealed the presence of flavonoids and phenols in the plant extract, indicating that they were the major agents capable of reducing zinc nitrate salt. According to our x-ray diffraction (XRD) results, ZnO-NPs exhibit a particular phase wurtzite structure. The ZnO-NPs are spherical in shape and have an average size of 15 nm, according to the measurements of electron microscope (SEM) and transmission electron microscope (TEM) measurements. Energy dispersion (EDX) analysis demonstrates that the NPs are mainly composed of zinc and oxygen. The zeta potential of these nanoparticles shows that they are very stable. The antibacterial activity of ZnO-NPs was tested using agar dilutions with a variety of gram-positive and gram-negative microorganisms. According to the research results, ZnO-NPs can be established as an extremely specific antibacterial agent for a wide variety of organisms to prevent bacterial growth. Furthermore, the antioxidant properties of ZnO-NPs were determined using the 2,2 diphenyl-1-picrylhydrazyl hydrate (DPPH) radical scavenging approach, and the IC50 value of 38 μg/mL was measured for ZnO-NPs. Furthermore, the biosynthesized ZnO-NPs showed significant catalytic performance of methyl orange (MO) under UV irradiation. Overall, ZnO-NPs in their produced state have excellent potential in biomedical and wastewater treatment applications. Radical scavengers were used to evaluate the role of radicals in the reaction mechanism.
Keywords: Hibiscus sabdariffa L. extract; ZnO; antibacterial; antioxidant; photocatalysis.