Microwave-Assisted Synthesis and Characterization of an Agriculturally Derived Silver Nanocomposite and Its Derivatives

Abstract

Nanocomposites and activated carbons are well known and tested effective adsorbents in the areas of water purification and water treatment. However, commercial nanocomposites and activated carbons are expensive; therefore, it has become increasingly pertinent to produce affordable nanocomposites and activated carbons. Herein, we report a microwave assisted synthesis of an agriculturally derived nanocomposite, maize tassel-silver (MtAg) nanocomposite. Controlled growth of silver nanoparticles (AgNPs) was formed with maize tassel powder (a lignocellulosic material) and silver nitrate in the ratio (1:1) and optimized microwave conditions of 1 h, 60 °C and 800 W. The MtAg nanocomposite was activated physically and chemically using air at 400 °C and nitrogen at 600 °C and H3PO4 at 500 °C respectively. The activated and non-activated MtAg nanocomposite were characterized using energy dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM), thermogravimetric analysis, Brunauer–Emmett–Teller (BET) and powder X-ray diffraction (XRD). The irregular sized, spherical shape of AgNPs was confirmed on the newly formed MtAg nanocomposite material using TEM. The XRD patterns showed diffraction peaks at 2θ of about 37.8°, 43.6°, 64.6°, 76.8° and 81.3°. The synthesized MtAg nanocomposite (ratios 1:1, 3:1 and 5:1/maize tassel vs. silver nitrate) exhibited low BET surface areas of 0.42, 0.36 and 0.13 m2/g, respectively. Upon physical activation, a BET surface area (86.27 m2/g) was recorded and this increased significantly to 331 m2/g, with chemical activation. The synthesized MtAg nanocomposite was found to be an improved form of the original tassel material in terms of thermal stability, crystallinity and structural morphology.