Green Synthesis and Physicochemical Characterization of Copper Nanoparticles Using Citrus limon Ethanolic Peel Extract

The present study focuses on the green synthesis and characterization of copper nanoparticles (CuNPs) using ethanolic peel extract of Citrus limon as a reducing and stabilizing agent. Green nanotechnology has emerged as an environmentally sustainable alternative to conventional chemical and physical nanoparticle synthesis methods, which often involve toxic chemicals and hazardous reaction conditions. In this study, fresh Citrus limon peels were shade-dried, powdered, and Soxhlet-extracted with ethanol to obtain a phytochemical-rich extract containing flavonoids, phenolics, citric acid, and ascorbic acid. Copper nanoparticles were synthesized by reacting the ethanolic extract with 0.1 M copper sulfate solution under continuous magnetic stirring, followed by pH adjustment using sodium hydroxide solution. The formation of CuNPs was confirmed by a visible colour change from light blue to dark green. The synthesised nanoparticles were characterised using UV–Visible spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), and elemental mapping. UV–Visible spectroscopy confirmed nanoparticle formation through characteristic surface plasmon resonance peaks. XRD analysis revealed the nanocrystalline and partially amorphous nature of the CuNPs. SEM analysis showed granular and agglomerated morphology with rough surface texture, while EDS confirmed copper as the major elemental component. Elemental mapping demonstrated uniform distribution of copper throughout the sample. The study concludes that Citrus limon peel extract serves as an efficient eco-friendly reducing and capping agent for the synthesis of stable copper nanoparticles with promising applications in biomedical, catalytic, environmental, and industrial fields.