Zinc oxide nanoparticles fabrication using Moringa oleifera Lam. seed extract—impact on phytotoxic, photocatalytic, and antimicrobial activities

In the present study zinc oxide nanoparticles (ZnONPs) were synthesized using the seed extract of Moringa oleifera (Lam.) and its perspective was explored against biological applications. The biosynthesized nanoparticles were characterized and screened for the presence of phytochemicals and also assessed for their diverse properties such as phytotoxic, photocatalytic, and antimicrobial activities. Phytochemicals such as alkaloids, flavonoids, steroids, glycosides, polyphenols, proteins, and carbohydrates were detected in the biosynthesized ZnONPs which proved to be a potential stabilizing and capping agent in the formation of zinc oxide nanoparticles. The results of the UV–Vis spectrum revealed the formation of surface plasmon bands at 223.5 nm indicating the formation of ZnONPs. FT-IR analysis confirmed the presence of functional groups that contributed to the formation of ZnONPs. SEM–EDS analyses confirmed the structural morphometry of nanostructured ZnONPs and their high stability while the XRD revealed the crystalline nature of the biosynthesized nanoparticles. The particle size of 15.3 nm indicated the nanostructure of the biosynthesized nanoparticle. Phytotoxicity studies revealed an appreciable germination rate in the green gram seedlings treated with ZnONPs. The photocatalytic activity also confirmed the potential of ZnONPs in the degradation of crystal violet. The isotherm, kinetics, and thermodynamics studies validated the mechanism of adsorption of crystal violet onto ZnONPs. The adsorption process fits well with both the Langmuir and Freundlich models and obeyed pseudo-second-order kinetic model, implying the removal of crystal violet onto ZnONPs. According to thermodynamic studies, the adsorption capacity dropped as the temperature rose, indicating the exothermic process. The biosynthesized ZnONPs displayed enhanced microbicidal activity against the tested bacterial and fungal isolates.