As part of the desire to save the environment through “green” chemistry practices, we herein report
an environmentally benign synthesis of silver nanoparticles (Ag-NPs) using cellulose extracted from
an environmentally problematic aquatic weed, water hyacinth (WH), as both reducing and capping
agent in an aqueous medium. By varying the pH of the solution and reaction time, the temporal evolutions
of the optical and morphological properties of the as-synthesised Ag-NPs were investigated.
The as-synthesised cellulose capped silver nanoparticles (C–Ag-NPs) were characterised using Fourier
transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), transmission electron
microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The maximum surface
plasmon resonance (SPR) peak decreased as the pH increased indicating that an increase in the pH of
the solution favoured the formation of smaller particles. In addition, instantaneous change in the colour
of the solution from colourless to brown within 5 min at pH 11 showed that the rate of reduction is faster
at this pH compared to those at lower pH. The TEM micrographs showed that the materials are small,
highly monodispersed and spherical in shape. The average particle mean diameters were calculated to
be 5.69
±
5.89 nm, 4.53
±
1.36 nm and 2.68
±
0.69 nm nm at pH 4, 8 and 11 respectively. The HRTEM confirmed
the crystallinity of the material while the FTIR spectra confirmed the capping of the as-synthesised
Ag-NPs by the cellulose. It has been shown therefore that based on this synthetic method, this aquatic
plant can be used to the advantage of mankind.