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Title: Characterisation of silver and zinc oxide nanoparticles biosynthesized using Ocimum gratissimum and Vernonia amygdalina plant leaf extracts
Author: Mfon, Rebecca
ISNI:       0000 0004 7961 6800
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2019
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The need to reduce environmental pollution and make planet Earth safer for her inhabitants has led to the adoption of scientific methods which yield safer by-products. Nanoparticles which have in the Science world recently attracted much attention, have been synthesized and put into a wide range of applications but the main concern has been to ensure that the by-products from such processes are less toxic, and that their sizes are controlled for specific applications. Though chemical and Physical methods can be used for their synthesis, the biosynthesis option reported to be fast, cheap and environmentally friendly and more recently the use of plant leaf extracts has been preferred because the plant extracts through their inherent biomolecules do not only make the nanoparticles, they cap and can stabilize them. In view of this, this work studied the effect of Ocimum gratissimum (Og) and Vernonia amygdalina (Va) plant leaf extracts on the synthesis of silver and zinc oxide (ZnO) nanoparticles. The resulting nanostructures were characterized using optical spectroscopy and electron microscopy. Boosting food production can make it more affordable especially to the low-income earners in any society therefore this work also investigated the interactive effect of pH of synthesis and concentration of colloidal solution of the ZnO nanoparticles (used as Nano fertilizer) on the growth parameters (seedling characteristics and vegetative growth) of Amaranthus cruentus. Amaranthus cruentus is widely eaten in my country Nigeria but is still not within the reach of the average Nigerian. This research therefore used the zinc oxide nanofertilizer to grow this plant (A. cruentus) and determined the plant treatments which give best seedling characteristics or enhance the vegetative growth of the plants. The critical limit for the nanoparticles used were also determined. While the Amaranth studies showed that the ZnO Nano fertilizer enhanced the growth of the plant, it was discovered that beyond 500mg/L concentration, the colloidal solution of the ZnO nanofertilizer became toxic and even resulted in chlorosis in some cases. Furthermore, from available literature, it is obvious that not much has been done on the electrodeposition of silver on gold in the presence of plant leaf extracts particularly the ones listed for this research. This therefore was also explored using cyclic voltammetry and chronoamperometry techniques and the morphology of the silver thin films from aqueous iii silver nitrate in the presence of each of the chosen two leaf extracts was examined using the Atomic Force Microscope (AFM). The electrodeposition experiment gave silver films whose thickness and grains sizes were refined and found to be plant leaf extract dependent.
Supervisor: Sarua, Andrei ; Hall, Simon Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available