Abstract

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Magnetite nanoparticles have been produced by green synthesis method. Aqueous extract of Mangifera indica leaves was used as reducing agent for co-precipitation of magnetite from iron (II) and iron (III) salts 3 in 1:2 molar ratio. Optimisation of the process was carried out using 2 factorial design of experiments taking into consideration stirring time of reaction medium, temperature and volume of extracts with 2 hdrodynamic particle size as response. A 2 factorial design was afterwards conducted with temperature of reaction medium and volumetric ratio of plant extracts to iron precursor as factors and hydrodynamic particle size as response. Characterisation of the nanoparticles was done using UV-visible spectrometer, Dynamic Light Scattering (DLS) method for hydrodynamic particle size measurement, X-ray diffraction (XRD) and High Resolution Transmission Electron Microscopy (HRTEM). Results obtained reveals that the best parameter for the synthesis of magnetite nanoparticles is a volume of precursor to plant extract ratio o of 1:15 at a temperature of 70 C. Measurement of particle size of the magnetite nanoparticles using DLS method gave an average hydrodynamic particle size of 143.9 nm; the particles size measurement using Scherer's equation from the XRD spectra gave 52.04 nm, while the High Resolution Transmission Electron Microscopy result indicated that the nanoparticles are spherical in nature, with a mean particle size of approximately 9 nm. It can be inferred from the analyses that, ratio of iron precursors to plant extract, temperature, and stirring time, played important roles in size of particles.

Keywords: Optimisation, Magnetite, Nanoparticles, Factorial Design.