title: Green synthesis of silver nanoparticles using cellulose extracted from an aquatic weed; water hyacinth.
abstract: 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.
authors.affiliation: Department of Chemistry and Chemical Technology, Walter Sisulu University, Mthatha Campus, Private Bag XI, Mthatha 5117, Eastern Cape, South Africa.
authors.forename: Tanki
authors.initials: T
authors.lastname: Mochochoko
authors.forename: Oluwatobi S
authors.initials: OS
authors.lastname: Oluwafemi
authors.forename: Denis N
authors.initials: DN
authors.lastname: Jumbam
authors.forename: Sandile P
authors.initials: SP
authors.lastname: Songca
mesh_terms: D059001:Aquatic Organisms / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry* / Q000302:isolation & purification; D031806:Eichhornia / Q000737:chemistry*; D055772:Green Chemistry Technology; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D018520:Plant Shoots / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D013997:Time Factors
chemical_list: D012834:Silver; D002482:Cellulose
keywords: Capping agent; Cellulose; Echhornia crassipes; Silver nanoparticles; Water hyacinth; pH