Effect of secondary metabolites from several leaf extracts on the green synthesized-ZnO nanoparticles

This study explores a green synthesis approach for zinc oxide nanoparticles (ZnO NPs) using eco-friendly leaf extracts from mango (Mangifera indica), kapok (Ceiba pentandra), and oil palm (Elaeis guineensis Jacq.) trees. The research investigates the effect of the extracts' secondary metabolites on the synthesized ZnO NPs. Qualitative analysis identified the presence of alkaloids, phenols, steroids, and saponins in varying concentrations within each extract. ZnO nanoparticles were successfully synthesized using all three extracts, confirmed by FT-IR spectroscopy with a characteristic Zn–O peak at 416.3 cm⁻¹. XRD analysis revealed the crystalline structure of the nanoparticles, with an additional peak in ZnO_CPLE suggesting potential impurities. SEM images demonstrated the influence of secondary metabolites on particle size and morphology. ZnO_EGLE, containing both phenols and saponins, exhibited the smallest and most uniform nanoparticles (43.3 nm) compared to ZnO_CPLE (94.5 nm) and ZnO_MILE (74.9 nm). TEM analysis further supported these findings, highlighting the crucial role of phenols and saponins as capping agents in controlling particle size and agglomeration. This research suggests a promising green synthesis route for ZnO NPs using these leaf extracts, potentially tailoring particle properties based on the specific secondary metabolite profile.