Green Synthesis of Iron Nanoparticles (FeNPs) Using Plant Extracts and their Application in the Degradation of A Vat Dye

Abstract

The growing concern for environmental sustainability calls for the adoption of ‘greener’ techniques for remediation purposes. The application of green synthesized iron nanoparticles (FeNPs) provides a promising route in this context. This thesis reports a facile room-temperature synthesis of stable iron nanoparticles utilizing aqueous extract of peels of Musa sp. (Plantain) and Tetrapleura sp. (‘Prekese’). The extracts served as both reductants and capping agents owing to the myriad of polyphenolic compounds present. Synthesized nanoparticles were confirmed through visual inspection of colour changes and by the use of spectroscopic and microscopic techniques. Microstructurally, the synthesized iron nanomaterials using Tetrapleura tetraptera were non-discrete particles whereas the plantain (Musa sp.) mediated synthesized iron nanoparticles were uniformly shaped with approximate diameter within 80 nm and 100 nm range. Based on ultraviolet-visible (UV-Vis) data, prepared iron nanomaterials showed a maximum plasmon resonance absorbance at 300 nm, typical of nanoscale iron. Fourier transform infrared spectroscopy (FTIR) analysis indicated the presence of various functional groups, particularly hydroxyl, present in the extracts, which may be responsible for capping of nanoparticles. The synthesized iron nanomaterials exhibited good efficiency in the degradation of Vat orange dye. The degradation process was highly dependent on contact time, pH, temperature, initial adsorbate concentration, and adsorbent dose. The sorption equilibrium of the dye on the nanoparticles was reached within 240 min of subjecting the aqueous solution of dye to the synthesized nanoparticles and was best explained by the Freundlich adsorption model. The results from this study illustrate that biosynthesized iron nanomaterials offer a cost-effective, environmentally friendly and efficient means of remediation of dye-contaminated industrial effluents.