Removal of methylene blue using biosynthesized silver nanoparticles

Abstract

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