Effect of pH on the Environmentally Friendly Fabrication of Silver Nanoparticles Using Rambutan Peel Extract

Abstract

Silver nanoparticles (AgNPs) have been intensively researched because of their wide range of applications in the areas of catalysis, optics, antimicrobials and biomaterials production. The pH of the reaction mixture is one of the crucial parameters for improving the properties of AgNP, including size, morphology and agglomeration. In this study, AgNPs were synthesized by a biological method using rambutan peel extract. The effect of pH on the resultant biogenic AgNPs was observed by varying the pH values to be 2, 4, 6, 8, 10 and 12. The biosynthesized AgNPs was characterized by UV-Vis spectroscopy (UV-Vis), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX) and Zeta potential analysis. The results showed the formation of AgNPs with size ranging from 15-120 nm in diameter. Phytochemical compounds in the extract are likely responsible for the reduction and stabilization of AgNPs. The shape, size and stability of AgNPs depend on the pH of the solution. AgNPs prepared at pH 2, 4 and 6 were of various shapes with a large size distribution. Those synthesized in basic solution (pH 8, 10 and 12) were spherical in shape. The results indicate that pH 8 is optimal for synthesis of AgNP as it offers pureness and fineness with narrow size distribution. Furthermore, biosynthesized AgNP exhibits antibacterial activity against the growth of selected human pathogens.