Effect of Ag+ ion Concentration on the Reaction Kinetics and Shape of Nanoparticles Synthesised by Green Chemical Approach

The effect of varying Ag+ ion concentration on the green chemical reaction with a fixed tea aliquot concentration has been studied in detail with the help of UV-visible absorption spectra. With increase in the concentration of Ag+ solution the position of surface plasmon band systematically increased from 435 nm 450 nm. The reaction followed first order kinetics and the rate of reaction increased in a linear fashion with k = 3.54 x 10(4) min(-1) for 0.5 mL to k = 1.86 x 10(-3) min(-1) for 3.0 mL Ag+ solution. X-ray diffraction patterns showed an enhanced (200) reflection for 3.0 mL Ag sample. The shape of Ag nanoparticles could be effectively tuned from spherical to cuboid with increase in silver content as evidenced from scanning electron and transmission electron micrographs. The average particle size of Ag NPs increased from 25 nm to 55 nm with increase in the Ag+ content of the reaction.