Optimization of green synthesized zinc oxide nanoparticles using Quercus infectoria gall extract: A response surface methodology approach

Zinc oxide nanoparticles (ZnONPs) were synthesized via an eco-friendly green route using Quercus infectoria gall extract as a phytochemical rich source of capping and stabilizing constituents. The synthesis process was optimized using response surface methodology (RSM) based on a Box Behnken design to evaluate the effects of pH, temperature, and ZnSO 4 :extract ratio on particle size, polydispersity index (PDI) and percentage yield. Statistical analysis revealed that particle size and PDI followed quadratic models, while percentage yield exhibited a linear relationship with process variables. Among the factors, ANOVA revealed that extract concentration was the dominant synthesis parameter influencing particle size, PDI, and percentage yield, followed by temperature and pH. The optimized conditions were identified as pH 7.9, 79°C, and ZnSO 4 :extract ratio of 1:3, yielding nanoparticles with a predicted particle size of 62 nm, PDI of 0.19, and yield of 91%. Experimental validation under optimized conditions resulted in a particle size of 49.1 nm, PDI of 0.20, and yield of 89%, demonstrating good agreement with model predictions. Characterization studies using DLS, FTIR, FESEM, and EDAX confirmed the formation of stable ZnO nanoparticles with uniform size distribution, characteristic Zn–O vibrations, nanoscale morphology, and elemental composition. The study highlights the effectiveness of green synthesis combined with statistical optimization in producing high quality ZnO nanoparticles with potential applications in pharmaceutical and biomedical fields.