Green synthesis of silver nanoparticles using gallic acid as reducing and capping agent: effect of pH and gallic acid concentration on average particle size and stability

We reported a green method for the synthesis of silver nanoparticles (AgNPs) using Gallic acid (GA) as both reducing and capping agent. The effect of pH and GA concentration was investigated on the average size and stability. The synthesized NPs were characterized by UV-Vis spectroscopy, DLS and zeta potential. The pH of 9 for AgNPs synthesis was optimum in order to formation of more NPs with the smaller average size. Then, the effect of GA concentration on average size and stability of AgNPs at optimum pH were investigated. A large number of NPs with smaller average size were obtained at the GA concentration of 7 mM. Zeta potential values indicated that AgNPs had good stability at all of conditions. The characterization through XRD and TEM techniques inferred that the NPs synthesized under optimum conditions were metallic silver with a FCC crystalline structure and the average size of 5.77 nm, respectively.