Green Synthesis and Multi-technique Characterization of Copper Nanoparticles Mediated by Citrus sinensis Peel Essential Oil

Abstract

Background: Green synthesis of nanoparticles using plant-derived materials has gained increasing attention due to environmental and safety concerns associated with conventional chemical methods. Citrus sinensis essential oil, obtained from agro-waste citrus peels, contains bioactive phytochemicals capable of acting as natural reducing and stabilizing agents. This study aimed to synthesize copper-based nanoparticles via a green route and evaluate their physicochemical properties. Methods: Copper nanoparticles were synthesized via a green, biogenic route using Citrus sinensis essential oil. The synthesized nanoparticles were characterized using UV-Visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and gas chromatography-mass spectrometry (GC-MS). Results: UV-Visible spectroscopy showed a characteristic absorption band at 300-320 nm, indicating nanoparticle formation. FTIR analysis revealed functional groups such as hydroxyl, carbonyl, and aliphatic moieties, confirming phytochemical involvement in reduction and stabilization. SEM images (8000×-10,000×) showed agglomerated clusters with irregular and porous morphology, while the primary particle size was inferred to be nanoscale. XRD patterns exhibited diffraction peaks consistent with nanocrystalline copper-based structures; however, peak broadening and low intensity suggest weak crystallinity and possible phase overlap. GC-MS identified 40 phytochemical constituents, predominantly oxygenated monoterpenes and sesquiterpenes, including cis-(-)-1,2-epoxy-p-menth-8-ene, decanal, D-carvone, and α-copaene, which likely contributed to nanoparticle formation and stabilization. Conclusion: Citrus sinensis essential oil serves as an effective biogenic agent for the synthesis of copper-based nanostructures, providing an eco-friendly approach for agro-waste valorization. The characterized properties suggest potential applications in agriculture, environmental management, and vector control; however, further studies are required to validate their biological and functional performance.