Evaluation of the kinetic and catalytic properties of biogenically synthesized silver nanoparticles

Present work encompasses the facile green and biogenic preparation of silver nanoparticles (AgNPs) using of cumin seeds (Cuminum cyminum) extract. The phytochemicals present in seeds extract, possessing strong anti-oxidant potential, reduce silver (Ag+) ions and subsequently stabilize the newly formed silver (Ag-0) nuclei. The effect of pH, concentration of seeds extract, reaction time and stability of nanoparticles were investigated by UV-visible spectroscopy. The reddish-brown color at a wavelength of 422 nm corresponding to surface plasmon resonance (SPR) absorption, confirmed the formation of AgNPs. Further, the nucleation, growth and stabilization phases have been examined. The rate constant value suggests the rapid formation of stable AgNPs. The nanoparticles were further investigated by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM) and Fourier transform infrared (FT-IR) spectroscopy. The biosynthesized AgNPs had been observed to be spherical in shape with an average particle size of 16 +/- 2 nm as calculated from TEM images. Furthermore, the stable AgNPs were excellent nanocatalysts towards borohydride reduction of various anthropogenic dye pollutants viz. methylene blue (MB), methyl red (MR), rhodamine-B (Rh-B) and 4 nitrophenol (4-NP). (C) 2018 Elsevier Ltd. All rights reserved.