Removal of methylene blue using biosynthesized silver nanoparticles

Document Type : Original Research Paper


Department of Chemistry, Arak Branch, Islamic Azad University, Arak, Iran



In recent decades, the focus of science and industry has been concentrated on production of metal
nanoparticles (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, extract
volume, concentration of silver nitrate, temperature and reaction time were optimized. Silver nanoparticles
were 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 performed
at optimal condition by using UV-Vis spectroscopy, X-ray diffraction (XRD), Transmission electron
microscopy (TEM), Field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared
spectroscopy (FT-IR). Also study of first and second-order kinetic to the adsorption process of methylene
blue by synthesized NPs at the optimal condition was performed. Resulted absorption peaks, indicated
strong peaks around the λ = 420 nm which is the certain wavelength for silver NPs. TEM studies indicated
that the silver NPs are spherical with an average diameter of 13 nm. In adsorption kinetic studies have
found 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 stabilizing
the metal NPs, due to their antioxidant properties and high secondary constituents and have high potential
for synthesis of metal NPs which can be used in the removal of dye contaminants.