3. Electronic Theses and Dissertations (ETDs) - All submissions

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    Extending the understanding of metal loading sites on a novel titania nanocatalyst
    (2016) Malibo, Petrus Molaoa
    The hydrothermal method of synthesis was successfully utilized to produce the rutile dandelion support onto which different noble metals were deposited using the deposition precipitation method to prepare the Au-TiO2, Pt-TiO2, Pd-TiO2 and Rh-TiO2 catalysts. The catalysts were prepared at different metals loadings. The deposition precipitation method was also employed to deposit the same metals (Au, Pt, Pd and Rh) onto the rutile (110) and (111) crystal surfaces to model the catalysts. Transmission electron microscopy, scanning electron microscopy and powder X-ray diffraction were used as the main characterization techniques to study the preferred deposition sites of the metals as well as the composition of the catalysts. TEM analysis showed the metals to deposit onto the sides and tips of the rutile nanorods making up the dandelion support structure. SEM analysis showed the metals to deposit onto the (110) and (111) crystal surfaces with the exception of Pd which deposited onto the (111) and (001) surfaces only. TEM analysis showed that the metals agglomerated following Temperature-Programmed Reduction (TPR) under H2 gas. TPR analysis showed strong-metal-support interaction for the Pt, Pd and Rh catalysts.
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    Tracing metals: an archaeo-metallurgical investigation of metal working remains and artefacts from Thaba Nkulu in the Waterberg, South Africa
    (2016) Naylor, Michael Lewis
    Excavations conducted at Thaba Nkulu, an Early Farming Community homestead with associated metal working debris, led to the recovery of iron slag, tuyères, furnace lining, iron ore, copper artefacts and iron artefacts. Using the material recovered, this dissertation identified chemical signatures for metal artefacts and metal smelting and smithing associated material. This was achieved through the use of a combination of X-ray fluorescence spectrometry (XRF) and Scanning Electron Microscopy coupled with Energy-Dispersive X-Ray Spectroscopy (SEM-EDX). The artefacts recovered were analysed, and 3 sets of possible chemical signatures were recorded.
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