Characterization of crystallinity and molecular functional groups of silver nanoparticle-<i>Piptadeniastrum africanum</i> (Dahoma) sawdust composites synthesized <i>in-situ</i>

Abstract

Silver nanoparticles prepared by Turkevich method of reacting trisodium citrate as reducing agent with silver nitr-ate were incorporated in-situ with P. africanum (Dahoma) sawdust to produce nano-composite. Conventional X-ray powder diffraction of the nano-composite showed complex diffraction pattern, with line peak broadening in the crystalline phase and particle size widening in the amorphous region. The Miller indices of the four main peaks identified were (111), (200), (220) and (311); which confirmed the permitted reflections attributed to the presce-nce of crystalline silver. The mean lattice parameter calculated by Bragg’s law was 4.0903 Å, corresponding to face centred cubic Bravais lattice of silver. Using Scherrer formula, the crystallite sizes ranging from 4.95 – 15.25 nm were calculated for the broadened line peaks. The particle sizes in the amorphous phase were determined from the distorted peak or widening of the non-reflecting diffraction angles, and ranged from 1.35 - 4.10 nm. Fourier transform infrared (FTIR) spectroscopy of the nano-composite showed spectra lines of absorption peaks attributed to molecular functional group C-H-O at 1422.24 cm^-1 (major component of sodium citrate), while a band centred at 3450 cm^-1 was assigned to O-H bending or stretching of the interlayer water molecules (of H-bound and OH group vibrations), and the spectra line at 515.14 cm^-1 indicated the presence of Ag-O stretching modes. The crystalline characteristics of the nano-composites could be indicative of potential applications in industry.

Keywords: Nano-composite, X-ray Powder Diffraction, Crystallites, Lattice Parameter, Infrared Spectroscopy, Molecular Functional Groups