Removal of methylene blue using biosynthesized silver nanoparticles

In recent decades, the focus of science and industry has been concentrated on production of metalnanoparticles (NPs). In this study, the biosynthesis of silver NPs by using Tragopogon buphthalmoides(Tragopogon b.) plant was investigated. Various effective parameters on the synthesis such as pH, extractvolume, concentration of silver nitrate, temperature and reaction time were optimized. Silver nanoparticleswere synthesized under optimal conditions of 0.5 mL Tragopogon b. extract, 4.5 mM silver nitrate,pH=10, temperature=70 °C and synthesis time of 180 min. Characterization of synthesized NPs performedat optimal condition by using UV-Vis spectroscopy, X-ray diffraction (XRD), Transmission electronmicroscopy (TEM), Field emission scanning electron microscopy (FE-SEM) and Fourier transform infraredspectroscopy (FT-IR). Also study of first and second-order kinetic to the adsorption process of methyleneblue by synthesized NPs at the optimal condition was performed. Resulted absorption peaks, indicatedstrong peaks around the λ = 420 nm which is the certain wavelength for silver NPs. TEM studies indicatedthat the silver NPs are spherical with an average diameter of 13 nm. In adsorption kinetic studies havefound out, the adsorption process follows the second-order kinetic model (R2 = 0.9977, qe = 21.79 mg/g).The results of the present study showed that the plants play a significant role in reducing and stabilizingthe metal NPs, due to their antioxidant properties and high secondary constituents and have high potentialfor synthesis of metal NPs which can be used in the removal of dye contaminants.