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Development of silver-magnetite nanocomposites for cysteine sensing and dye degradation

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dc.contributor.supervisor Alula, Melisew Tadele
dc.contributor.supervisor Murape, Davison
dc.contributor.author Mazhani, Micode
dc.date.accessioned 2022-04-21T14:19:26Z
dc.date.available 2022-04-21T14:19:26Z
dc.date.issued 2020-11
dc.identifier.citation Mazhani, M. (2020) Development of silver-magnetite nanocomposites for cysteine sensing and dye degradation, Master's Thesis, Botswana International University of Science and Technology: Palapye. en_US
dc.identifier.uri http://repository.biust.ac.bw/handle/123456789/427
dc.description Thesis (Msc Mathematics and Statistics Sciences) --Botswana International University of Science and Technology, 2020. en_US
dc.description.abstract The development of easily recoverable and re-usable catalytic nanostructures exhibiting high performances using simple and cheap procedures for applications in bio-sensing and wastewater treatment technologies is currently a prominent area of research. Noble-metal inclusive magnetic nano-catalysts in particular, have of recent gathered interest owing to their ease of separation from reaction products, environmental benignity and improved activities through synergistic qualities and photo-thermal effects. Herein, silver-magnetite core-shell nanocomposites (Fe3O4@AgNPs) displaying enhanced peroxidase-like catalytic properties were successfully synthesised via a facile one step solvo-thermal procedure. Governed by Michaelis-Menten kinetics, the nanocomposites’ capacity to oxidize the colourless o phenylenediamine to the yellow coloured 2, 3-diaminophenazine in the presence of hydrogen peroxide progressively improved relative to Fe3O4 alone with increasing precursor AgNO3 to an optimum of 50 mM. Following a study and reaction optimisation conditions on the inhibitory behaviour of cysteine; a biomarker for Alzheimer and other neurological conditions, towards the peroxidase-like catalytic activity of these nanocomposites, a considerably cheap, selective and highly sensitive detection method for this amino acid was developed. With a low limit of detection of 87 nM, the formed cysteine sensor proved to be superior to some of the existing sensors. A simple silver mirror reaction was also employed to fabricate nano-silver decorated magnetite (Ag@ Fe3O4) free of the often activity limiting and environmentally unfriendly organic reagents. The nano-sized magnetite supports were synthesised using the precipitation method. Following synthesis optimisation procedures, these composites were found to effectively catalyse the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride more than 8 times repeatedly. With a normalised activity parameter k of 1.44 ×10−3 L. s−1 mg−1, the synthesised catalyst performed better than some reported nanostructures. Furthermore, the catalytic degradation methylene blue and Rhodamine 6G which are some of the many water pollutant dyes in textile industry effluents was achieved by these nanocomposites. Also, owing to their SERS property, Ag@ Fe3O4 particles were efficient in real-time monitoring the catalytic degradation of p-Nitrothiophenol by NaBH4. Characterisation of all the synthesised nanocomposites in this work was carried out via transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Thermogravimetric analysis and surface-enhanced infrared absorption spectroscopy. en_US
dc.language.iso en en_US
dc.publisher Botswana International University of Science and Technology en_US
dc.subject Bio-sensing en_US
dc.subject Wastewater treatment en_US
dc.subject Synergistic qualities en_US
dc.subject Photo-thermal effects en_US
dc.subject Alzheimer en_US
dc.subject Neurological conditions en_US
dc.subject Michaelis-Menten kinetics en_US
dc.title Development of silver-magnetite nanocomposites for cysteine sensing and dye degradation en_US
dc.description.level msc en_US
dc.description.accessibility unrestricted en_US
dc.description.department mss en_US


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