Browsing by Author "Taziwa, Raymond"

Now showing 1 - 4 of 4
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    Green synthesis of crystalline silica from sugarcane bagasse ash: Physico-chemical properties
    (MDPI, 2022) Seroka, Ntalane S.; Taziwa, Raymond; Khotseng, Lindiwe
    Sugarcane bagasse South Africa is an agricultural waste that poses many environmental and human health problems. Sugarcane bagasse dumps attract many insects that harm the health of the population and cause many diseases. Sugarcane ash is a naturally renewable source of silica. This study presents for the first time the extraction of nanosilica from sugar cane bagasse ash using L-cysteine hydrochloride monohydrate acid and Tetrapropylammonium Hydroxide. The structural, morphological, and chemical properties of the extracted silica nanoparticles was cross examined using XRD, FTIR, SEM, and TGA. SEM analysis presents agglomerates of irregular sizes. It is possible to observe the structure of nanosilica formed by the presence of agglomerates of irregular shapes, as well as the presence of some spherical particles distributed in the structure. XRD analysis has revealed 2 angles at 20, 26, 36, 39, 50, and 59 which shows that each peak on the xrd pattern is indicative of certain crystalline cubic phases of nanosilica, similar to results reported in the literature by Jagadesh et al. in 2015.
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    Nanostructured silicon derived from an agricultural residue bagasse ash via magnesiothermic reduction method
    (MDPI, 2023) Seroka, Ntalane S.; Taziwa, Raymond; Khotseng, Lindiwe
    This study presents the magnesiothermic reduction of silica into silicon. This reduction process occurs at a lower reaction temperature than its carbothermal counterpart. Furthermore, silica was extracted from sugarcane bagasse ash via a thermo-chemical treatment method using, for the first time, L-cysteine chloride monohydrate and used as a precursor in the production of silicon using magnesiothermic reduction. The as-synthesized nanocrystalline silicon’s physicochemical properties were investigated using XRD, Raman, FTIR, BET, and SEM. A peak at 2 of 28.2 with a crystallite size of 32 nm was discovered using X-ray diffraction spectroscopy. The pronounced peak around 518 cm􀀀1 was observed from the Raman spectrum, characteristic of crystalline silicon. The FTIR analysis showed two sharp peaks at 446 cm􀀀1 and 1056 cm􀀀1, indicative of the Si-O rocking mode and Si-O-Si stretching mode functional groups present.
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    A review of the green synthesis of zno nanoparticles utilising Southern African indigenous medicinal plants
    (MDPI, 2022) Mutukwa, Dorcas; Taziwa, Raymond; Khotseng, Lindiwe Eudora
    Metal oxide nanoparticles (NPs), such as zinc oxide (ZnO), have been researched extensively for applications in biotechnology, photovoltaics, photocatalysis, sensors, cosmetics, and pharmaceuticals due to their unique properties at the nanoscale. ZnO NPs have been fabricated using conventional physical and chemical processes, but these techniques are limited due to the use of hazardous chemicals that are bad for the environment and high energy consumption. Plant-mediated synthesis of ZnO NPs has piqued the interest of researchers owing to secondary metabolites found in plants that can reduce Zn precursors and stabilise ZnO NPs.
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    Solar energy materials-evolution and niche applications: A literature review
    (MDPI, 2022) Seroka, Ntalane S.; Taziwa, Raymond; Khotseng, Lindiwe
    The demand for energy has been a global concern over the years due to the ever increasing population which still generate electricity from non-renewable energy sources. Presently, energy produced worldwide is mostly from fossil fuels, which are non-renewable sources and release harmful by-products that are greenhouses gases. The sun is considered a source of clean, renewable energy, and the most abundant. With silicon being the element most used for the direct conversion of solar energy into electrical energy, solar cells are the technology corresponding to the solution of the problem of energy on our planet. Solar cell fabrication has undergone extensive study over the past several decades and improvement from one generation to another.