Eco-friendly production of gold nanoparticles from Ocimum sanctum leaves and their application in catalytic reduction of nitro-organic compounds in industrial wastewater

The growing need for sustainable and environmentally benign methods in nanotechnology has led to increased interest in plant-mediated synthesis of metal nanoparticles. This study synthesized gold nanoparticles (AuNPs) using an eco-friendly, green chemistry approach employing Ocimum sanctum (holy basil) leaf extract as a reducing and stabilizing agent. The bio-fabricated AuNPs were characterized using UV-Vis spectroscopy, FTIR, XRD, TEM, SEM, and elemental mapping analysis to determine their optical properties, functional groups, crystalline nature, and morphology. UV-Vis spectroscopy revealed a characteristic surface plasmon resonance (SPR) peak at approximately 536 nm, indicating the successful synthesis of AuNPs. X-ray diffraction (XRD) analysis confirmed the crystalline nature of the nanoparticles, displaying distinct diffraction peaks corresponding to the face-centered cubic (fcc) structure of gold. Transmission electron microscopy (TEM) further illustrated the morphology of the synthesized AuNPs, revealing predominantly spherical particles with a uniform size distribution ranging from 7 to 37 nm. The synthesized nanoparticles exhibited excellent catalytic activity in reducing toxic nitro-organic compounds, such as 4-nitrophenol and 4-nitroaniline, commonly found in industrial wastewater. Kinetic studies confirmed that the reduction followed pseudo-first-order kinetics in the presence of NaBH4. This green synthesis approach provides a sustainable alternative to conventional chemical methods and demonstrates practical utility in environmental remediation applications. The results suggest that Ocimum sanctum-derived AuNPs could serve as efficient, low-cost, and eco-friendly catalysts for detoxifying industrial effluents.