Synthesis and characterization of iron nanoparticles using leaves extract of Phyllanthus amarus and its application in crystal-violet degradation

Nanomaterials play a crucial role in the photocatalytic degradation of dyes in wastewater. In this study, iron oxide nanoparticles (Fe₃O₄-NPs) were synthesized via a green approach using Phyllanthus amarus leaf extract and evaluated for their effectiveness in degrading crystal violet, a common cationic dye. The novelty of this work lies in the dual functionality of P. amarus extract as both reducing and capping agent, offering a sustainable and eco-friendly alternative to conventional physical and chemical synthesis methods. Fresh P. amarus leaves harvested from the Federal University of Technology Owerri were processed into aqueous extract and reacted with 0.01 M FeCl₃·6H₂O in a 1:1 volume ratio, leading to a rapid color change indicating nanoparticle formation. The synthesized nanoparticles (PaFeNPs) were characterized using UV-Vis spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). UV-Vis analysis revealed a characteristic absorption peak at 286 nm due to surface plasmon resonance. XRD confirmed the presence of Fe₃O₄ with an average crystallite size of ~9.13 nm, while SEM and TEM revealed irregular morphologies and an average particle size of ~86.2 nm, indicating aggregation due to magnetic interactions. The photocatalytic activity of PaFeNPs was tested under UV and dark conditions. Results showed up to 89% degradation of crystal violet within 90 minutes under UV light, significantly outperforming the dark condition, thereby confirming their light-assisted catalytic potential. The presence of bioactive phytochemicals such as flavonoids, terpenoids, and reducing sugars in the extract contributed to the efficient synthesis and stabilization of the nanoparticles. This study demonstrates the feasibility of Phyllanthus amarus-mediated green synthesis of iron oxide nanoparticles as a cost-effective, environmentally safe, and scalable solution for industrial dye remediation.