Phytochemical-Mediated Green Synthesis of Zinc Oxide Nanoparticles from Azadirachta indica Extract for Antimicrobial Wastewater Purification
The development of sustainable synthetic routes for functional nanomaterials is essential for advancing environmentally benign technologies for water treatment. Herein, zinc oxide (ZnO) nanoparticles were synthesized through a green approach employing aqueous leaf extract of Azadirachta indica (neem) as both the reducing and stabilizing agent. The influence of precursor-to-extract ratio (1:1 and 1:2) and reaction temperature (room temperature and 60 °C) on nanoparticle formation and performance was systematically investigated. Formation of the nanoparticles was initially evidenced by colour change during synthesis and further characterized using Fourier-transform infrared (FTIR) spectroscopy, which revealed O–H, C=O, and C–N functional groups associated with phytochemicals involved in nanoparticle reduction and surface stabilization, together with Zn–O vibrational bands confirming ZnO formation. The synthesized materials exhibited pH values ranging from mildly acidic to alkaline depending on the synthesis conditions, indicating that reaction parameters significantly influenced nanoparticle stability. The antimicrobial performance of the ZnO nanoparticles was evaluated using contaminated wastewater containing aerobic mesophilic bacteria. Nanoparticles prepared using the higher neem extract ratio (1:2) and applied at 0.5 g demonstrated the greatest reduction in bacterial load, indicating concentration-dependent antimicrobial activity. The enhanced performance is attributed to the synergistic effects of phytochemical surface capping, high surface reactivity, and ZnO-mediated disruption of bacterial cells. These findings demonstrate that neem-mediated ZnO nanoparticles represent an environmentally sustainable material for wastewater disinfection and highlight the potential of plant-assisted nanomaterial synthesis for low-cost water purification technologies.
KeyWords– AERONET, Green synthesis, Zinc oxide nanoparticles, Azadirachta indica, Wastewater purification, Antimicrobial activity.
