Theses

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A long essay or dissertation or thesis involving personal research, written by postgraduates of University of Ghana for a university degree.

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    Synthesis andApplication of Fe-Doped TiO2-Halloysite Nanotubes Composite and Their Potential Application in Water Treatment
    (Advances in Materials Science and Engineering, 2019) Nyankson, E.; Agyei-Tuffour, B.; Adjasoo, J.; et al.
    In this work, the potential application of TiO2-Fe-HNT photocatalyst-adsorbent composite in water treatment technologies was confirmed. ,e photocatalyst-adsorbent composite (TiO2-Fe-HNTs) was synthesized by the hydrothermal method and characterized by X-ray diffraction, thermogravimetric analysis, Fourier-transform infrared spectroscopy, scanning electron mi croscopy-energy dispersive X-ray spectroscopy, and diffuse reflectance spectroscopy. ,e adsorption and photocatalysis mechanism by the TiO2-Fe-HNT composite were examined on methylene blue dye, rhodamine blue dye, naproxen sodium (pharmaceutical drug waste), and imidacloprid (pesticide). ,e TiO2-Fe-HNT composite was active in UV and visible regions of the electromagnetic spectrum. ,e adsorption and photocatalytic efficiency increased with increasing amounts of HNTs. ,e photocatalyst-adsorbent composite exhibited excellent removal efficiency for pharmaceutical waste (naproxen sodium) and pesticides (imidacloprid). An adsorption equilibrium data fitted well with the pseudo-second-order kinetics for both methylene blue and rhodamine blue dyes with the intraparticle model describing its rate-controlling steps. ,e Langmuir and Freundlich isotherm models further described the adsorption of methylene blue and rhodamine blue molecules, respectively.
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    Awaso bauxite red mud-cement based composites: Characterisation for pavement applications
    (Case Studies in Construction Materials, 2017) Dodoo-Arhin, D.; Nuamah, R.A.; Agyei-Tuffour, B.; et al.
    This paper presents the development of Bauxite residue (red mud) based cement composite mortar blocks for applications in pavement construction. The experimental techniques considered include the structural, thermal, morphological, and microscopy analysis of the raw bauxite and red mud samples calcined at 800 °C. Composite mortar blocks of different batch formulations were produced and their physicochemical properties were investigated. The results show that the compressive strength of the as-prepared composite mortar blocks increased by ∼40% compared to the type M mortar strength of ∼2500 N/mm2 . The load-bearing applications of the composites are discussed to influence the adoption of the calcined red mud as a supplement in the production of low-cost Portland cement-based composite mortar blocks for the construction industry.
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    Layered Nanomaterials - A Review
    (2012) Yaya, A.; Agyei-Tuffour, B.; Dodoo-Arhin, D.; et al.
    Layered materials can become a myriad source of two-dimensional crystals if the layers can be separated from each other, for example via exfoliation. Potential applications for single-layer materials range from energy storage, electronics, and mechanical reinforcement of plastics, to life-saving applications such as drug delivery, medical imaging, and clean-up of toxic materials in the environment. Layered nanomaterials can be found naturally and can also be synthesized in the laboratory to suit certain specific applications. We describe here key layered materials including some naturally occurring (graphite, graphene, clays, layered hydroxides (LDHs)) and others that have been synthesized through chemical combination of some atomic species such as boron nitride (BN), transition metal oxides (TMOs), LDHs, and transition metal dichalcogenides (TDMs), along with a discussion of their properties and potential applications.
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    Application of Discarded Rubber Car Tyres as Synthetic Coarse Aggregates in Light Weight Pavement Concretes
    (American Journal of Materials Science, 2015) Dodoo-Arhin, D.; Mensah, S.A.; Yaya, A.; Agyei-Tuffour, B.
    The increasingly high cost of building construction materials is a major factor affecting quality housing delivery in Ghana. The current trend of continuous and increasing demand for these natural resources has necessitated extensive research into alternative low-cost construction materials such as recycled materials with comparable properties. The characteristics of concretes produced using locally available discarded rubber car tires as coarse aggregates have been investigated. Batch formulation of 0%, 25%, 50%, 75%, and 100% substitution of natural coarse aggregates with the rubber aggregates is considered. A comparison of the physico-mechanical properties of batch formulations by weight % and volume % have also been investigated. Generally, the compressive strength of the concretes decreased as the percentage of the rubber increased in the two batch formulations. At 25% replacement, the compressive strength of 9.26 N/mm2 (weight %), 11.56 N/mm2 (vol %) as compared to 14.80 N/mm2 and 24.00 N/mm2 respectively for the controlled program were obtained.
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    Characteristics Of Stabilized Shrink-Swell Deposits Using Eggshell Powder
    (2013) Nyankson, E.; Agyei-Tuffour, B.; Annan, E.; et al.
    Shrink-swell soils expand and heave or contract and crack during periods of high and low moisture content. The expansion and contraction cause the lifting and or sinking of structures, crack development, and eventual collapse of engineering structures. The need to stabilize such plastic soils to improve their load-carrying capacities cannot be overemphasized. Therefore in this article, the effect of lime contained in eggshells and its application in the stabilization of shrink-swell soils have been explored. 4wt% and 8wt% of eggshell powder were mixed with equal masses of two different soil samples from Dodowa (DD) and Adalekope (AD) in Ghana. The samples were characterized with X-ray fluorescence (XRF), Plasticity Index analysis (PI), Free Swell Index (FSI), pH test, and a grading test. The x-ray fluorescence results showed that eggshell contains about 52wt% of CaO, which is largely responsible for soil stabilization. The sample mixed with 8wt% eggshell powder showed a decreased PI, FSI, and a high silt/clay fraction. The results obtained have been discussed and can influence the application of eggshell powders for large-scale stabilization of expansive soils.