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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    The physico-mechanical influence of dehydroxylized activated local kaolin: A supplementary cementitious material for construction applications
    (Case Studies in Construction Materials, 2019) Marfo, K.K.; Dodoo-Arhin, D.; Agyei-Tuffou, B.; et al.
    This work presents the effect of partially replacing metakaolin with Portland limestone cement to produce mortars for construction. Teleku Bokazo kaolin was explored as an SCM for the production of mortars. The hydration product between Portland limestone and metakaolin was studied. The kaolin was heat treated to form metakaolin and partially used to replace Portland limestone cement (PLC) in mortars to explore the optimum replacement and its mechanical and durability effect. The samples were characterized using X-ray diffraction (XRD) for phases and crystallinity of the kaolin. Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) gave information on the functional groups formed during the hydration and structure and surface morphology respectively. The pastes and mortars produced were subjected to setting time, water absorption, flexure, and compression strength tests. The mechanical properties were observed to increase with increasing metakaolin replacements. Therefore, from the results obtained, it is suggested that a 20 % replacement of Portland limestone cement with Teleku Bokazzo metakaolin can be very suitable for construction applications.
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    Effects of Purity on the Mechanical Properties of Single-Walled Carbon Nanotubes-Polymer Nanocomposites
    (British Journal of Applied Science & Technology, 2013) Yaya, A.; Dodoo-Arhin, D.; Onwona-Agyeman, B.; et al.
    This study investigated the superior mechanical properties of single-walled carbon nanotubes (SWCNTs), and its polymer nanocomposites using 0.5% and 1% loading of raw and purified SWCNTs in an epoxy matrix and the degree of dispersion. The extent of load transfer between the nanotubes and the matrix was studied by analyzing the second order G’-band ( 2550 cm-1) of Raman Spectroscopy. The samples have been characterized by structural (Raman spectroscopy), mechanical (tensile test), physical, and microstructural (SEM) point of view. Purified SWCNTs give a better-reinforcing potential compared to raw SWCNTs. We found an increase in Young’s Modulus (3780 MPa-4263 MPa) and toughness (62 MPa-68.8 MPa) for the nanocomposites prepared from purified SWCNTs.
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    Fabrication and Characterisation of Ghanaian Bauxite Red Mud-Clay Composite Bricks for Construction Applications
    (American Journal of Materials Science, 2013) Dodoo-Arhin, D.; Konadu, D.S.; Annan, E.; et al.
    The behavior of Ghanaian-based bauxite red mud-Tetegbu clay composites has been investigated for their applicability in the ceramic brick construction industry as a means of recycling bauxite waste. The initial raw samples were characterized by X-ray diffraction (XRD), X-ray Fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (Tg-DTA). The red mud-clay composites have been formulated as 80%-20%, 70%-30%, 60%-40%, 50%-50% and fired at sintering temperatures of 800ºC, 900ºC and 1100ºC. Generally, mechanical strengths (modulus of rupture) increased with higher sintering temperatures. The results obtained for various characterization analyses such as bulk densities of 1.59 g/cm3 and 1.51 g/cm3 compare very well with literature and hold potential in bauxite residue eco-friendly application for low-cost recyclable constructional materials.
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    On the modelling of diffraction line profiles from nanocrystalline materials
    (Solid State Phenomena, 2010) Scardi, P.; Dodoo-Arhin, D.; Leoni, M.
    Recent advances in Line Profile Analysis of powder diffraction patterns must be paralleled by increasing attention to the quality and quantity of experimental data. The analysis of simulated data with different noise levels demonstrates the importance of statistical quality to reveal fine details of interest in the analysis of nanocrystalline materials, like the crystallite shape. It also shows how synchrotron radiation diffraction can improve data quality concerning laboratory measurements, both in terms of statistical quality and in terms of accessible information.
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    Effect of mechanical activation on mullite formation in an alumina-silica ceramics system at lower temperature
    (World Journal of Engineering, 2016) Obada, D.O.; Dodoo-Arhin, D.; Dauda, M.; et al.
    Purpose – This work aims to analyze the effect of mechanical activation on structural disordering (amorphization) in an alumina-silica ceramics system and the formation of mullite most notably at a lower temperature using X-ray diffraction (XRD). Also, an objective of this work is to focus on a low-temperature fabrication route for the production of mullite powders. Design/methodology/approach – A batch composition of kaolin, alumina, and silica was manually pre-milled and then mechanically activated in a ball mill for 30 and 60 min. The activated samples were sintered at 1,150°C for a soaking period of 2 h. Mullite formation was characterized by XRD and scanning electron microscopy (SEM). Findings – It was determined that the mechanical activation increased the quantity of the mullite phase. SEM results revealed that short-milling times only helped in mixing the precursor powders and caused partial agglomeration, while longer milling times, however, resulted in greater agglomeration. Originality/value – It is noted that a manual pre-milling of approximately 20 min and a ball milling approach of 60 min milling time can be suggested as the optimum milling time for the temperature decrease succeeded in the production of mullite from the specific stoichiometric batch formed.
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    Potentials of fabricating porous ceramic bodies from kaolin for catalytic substrate applications
    (Applied Clay Science, 2016) Obada, D.O.; Dodoo-Arhin, D.; Dauda, M.; et al.
    In this work, the suitability of using kaolin–styrofoam, sawdust, and high-density polyethylene to produce porous ceramic bodies was experimentally investigated. The kaolin samples (raw and beneficiated) were characterized by the XRD, SEM, TGA/DSC, and FTIR methods. Batch formulations of the samples including the kaolin and pore formers were formed into green bodies and fired to 1150 °C. The porosities of sintered bodies were calculated and given the following: apparent porosity: 28.63%–67.13% for all the samples investigated. Samples with high-density polyethylene (HDPE) pore formers showed minor surface cracks after firing but exhibited the highest porosity levels while samples with styrofoam and saw dust exhibited uniform surface characteristics with pores, thermal stability, and no visible surface cracks. It can be concluded that formulations containing 80% kaolin can be used for the production of ceramics with porosities as high as 67% if the right pore formers are used.
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    Silver nanoparticles decorated on a three-dimensional graphene scaffold for electrochemical applications
    (Journal of Physics and Chemistry of Solids, 2014) Bello, A.; Dodoo-Arhin, D.; Fabiane, M.; et al.
    Silver metal nanoparticles were decorated by electron beam evaporation on graphene foam (GF) grown by chemical vapor deposition. X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopy, and atomic force microscopy were used to investigate the structure and morphology of the graphene foam/silver nanoparticles (GF/Ag). Both samples were tested as electrodes for supercapacitors. The GF/Ag exhibited a significantly higher capacitive performance, including a specific capacitance value of ( 110 Fg 1 ) and excellent cyclability in a three-electrode electrochemical cell. These results demonstrate that graphene foam could be an excellent platform for metal particles to investigate improved electrochemical performance.
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    Co-fired Ghanaian clay-palm kernel shells pozzolan: Thermogravimetric, 29Si and 27Al MA NMR characteristics
    (Construction and Building Materials, 2017) Bediako, M.; Dodoo-Arhin, D.; Kevern, J.T.
    Pozzolanic materials are well known to improve the mechanical and durability properties of cement-based products including concrete, mortar, and paste. This has therefore made pozzolans widely accepted for construction. In this work, pozzolans were produced from a mixture of clay and palm kernel shells. A thermal gravimetric analyzer (TGA) was used to determine the lime consumption pattern of the calcined clay pozzolan whereas the 29Si and 27Al solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) was used to determine the aluminate and the silicate phases of the hydrated product. The TGA results showed that the calcined pozzolan containing palm kernel shells had a higher lime consumption pattern than the calcined clay and Portland cement. The 27Al MAS NMR showed that the calcined clay/palm kernel shell pozzolan produced stable mono-sulfate compounds in the octahedral environment. The 29Si MAS NMR results also proved that additional calcium silicate hydrates were formed in the cement containing pozzolan than in the Portland cement. The formation of stable mono sulfates combined with the formation of additional silicate hydrates are the reasons for the strength enhancement of the calcined materials than Portland cement
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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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    Photocatalytic Degradation of Azo and Rhodamine Dyes Using Copper (II) Oxide Nanoparticles
    (10th Int'l Conference on Advances in Science, Engineering, Technology & Healthcare, 2018) Mbu, E.E.; Dodoo-Arhin, D.; Ntwampe, S.K.; et al.
    Freshwater pollution by dyes from various industries are raising a lot of concern lately. Despite their well-known toxicity to humans, azo dyes make up over half of the used dye population. Rhodamines are also a well-used class of dyes in industry. This study employed a cost-effective, energy-efficient, environmentally benign method to degrade Methyl Orange (MeO), Methylene Blue (MB) and Rhodamine B (RhB) dyes. The photocatalyst used was copper (II) oxide (CuO) nano-sized particles synthesized from CuSO4 .5H2O, Cu(NO3 )2 .3H2O and NaOH via a simple solution route with neither a catalyst, template nor a surfactant. The nanoparticles were characterized and used for the photocatalytic degradation of the above dyes in the presence of H2O2 . The CuO nanoparticles synthesized from both copper precursors were found to degrade all dyes effectively over the same degradation time interval, recording an overall minimum degradation efficiency of 85 % and a maximum of 99 %.