Abstract

Green synthesis of nanomaterials finds the edge over chemical methods due to its environmental compatibility. The present study deals with the green synthesis of silver (AgNPs) nanoparticles using the aqueous extract of Alstonia scholaris without any catalyst, template, surfactant or any intermediate. The method was well controlled using ultrasonic cavitation so as to facilitate the high level of dispersion with an increase in rate of reaction. AgNPs was synthesized using silver nitrate in aqueous extract of Alstonia scholaris as a reducing agent. The size of AgNPs can be tuned using significant variation in reaction parameters. The as-synthesized nanomaterials were characterized using UV-visible spectroscopy, X-ray diffraction (XRD), Transmission electron microscopy (TEM), Field emission scanning electron microscope (FE-SEM) and Fourier transform infra-red spectroscopy. The optimized condition produces the AgNPs of size ~15-38 nm. The presence of aldehydic and ketonic compounds (alkaloids, flavonoids, pinocarvone and cryptone) potentially acts as reducing as well as stabilizing agents. Moreover, reduction of silver nitrate under controlled ultrasonication shows the implosive collapsing of bubbles, which results in attaining a very high temperature of solution with fast cooling at RT. Due to this uniform dispersion there are less chances of agglomeration of nanoparticles.

Keywords: Alstonia scholaris leaf extract, Ag NPs, Transmission electron microscopy, X-ray diffraction and ultrasonication.

Graphical Abstract