Green Synthesis of Nanoparticles from the Leaf and Bulb of Costus Woodsonii Plant for the Enhancement of Photocatalytic Activity and Antimicrobial Properties

In this study, ZnO nanoparticles (ZnONPs) were synthesized via a green route using leaf and bulb (flower) extracts of Costus woodsonii , enabling a comparative assessment of nanomaterials derived from two distinct plant parts in terms of their photocatalytic and antimicrobial performance. This dual‐extract strategy represents a novel aspect of the work, providing insight into how phytochemical variation influences nanoparticle properties and performance. The synthesized nanoparticle was characterized using XRD, FE‐SEM, TEM, EDS, and XPS analysis. Additionally, crystallite dimensions of ZnONPs were evaluated using derived models from the X‐ray diffraction data. The band gap of the synthesized particles was found to be 3.17 eV through UV–vis‐NIR. The photocatalytic degradation efficiency of the synthesized ZnONPs was assessed for the removal of ciprofloxacin antibiotic in the aqueous medium at varying concentrations and pH. At the neutral pH, leaf, bulb (flower), and chemically synthesized catalysts showed 99.237%, 93.458%, and 99.875% degradation, respectively. Catalytic efficiency of the developed ZnONPs was confirmed through application in water samples from two different rivers of Bangladesh (Khulshi River and Feni River). The antimicrobial effcacy of the samples was evaluated against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli , and Salmonella typhi . Three samples showed the same microbial inhibition concentration of 1.25 mg/mL for L. monocytogenes . Also, the minimum bactericidal concentration was evaluated to be 20 mg/mL for the three nanocrystals against all the organisms except L. monocytogenes . The findings from this study demonstrate the dual environmental remediation and antimicrobial potential of green‐synthesized ZnONPs.