Department of Materials Science and Engineering

Permanent URI for this collectionhttp://197.255.125.131:4000/handle/123456789/23127

Browse

Search Results

Now showing 1 - 10 of 176
  • Thumbnail Image
    Item
    Production and characterization of coconut shell charcoal-based bio-briquettes as an alternative energy source for rural communities
    (Heliyon, 2024-08-01) Yirijor,J.; Bere,A.A.T.
    The increasing demand for sustainable energy solutions has driven interest in the utilization of agricultural residues, such as coconut shells, for bio-briquette production. This study investigates the impact of binder types (cassava and corn) and concentrations (5 wt%, 10 wt%, 15 wt%) on the properties of bio-briquettes made from dried coconut shells with two particle sizes (40 mesh and 60 mesh). The experimental evaluation focuses on several performance indicators, including density, shatter index, percentage moisture content (PMC), percentage volatile matter (PVM), percentage ash content (PAC), percentage fixed carbon (PFC), higher heating value (HHV), ignition time, burning time, and boiling time. The results indicate that briquettes with 10 % fine charcoal cassava binder achieved the highest density of 0.764 g/cm3 due to improved compaction. Briquettes with 15 % coarse charcoal corn binder demonstrated the highest shatter resistance at 96.99 %, reflecting their superior structural integrity. The highest PMC and PVM values were observed in briquettes with 15 % coarse charcoal cassava binder, at 8.13 % and 31.25 %, respectively. Conversely, the highest PAC was 16.34 % for 5 % coarse charcoal cassava binder. Briquettes with 10 % fine charcoal corn binder exhibited the highest PFC of 70.79 % and HHV of 31.51 MJ/kg. Boiling times ranged from 15 min 53 s to 36 min 35 s, with the shortest boiling time for briquettes with 10 % fine charcoal corn binder. The findings highlight the superior mechanical properties and energy performance of bio-briquettes with specific binder concentrations and particle sizes. This study demonstrates the potential of coconut shell bio-briquettes as a viable and sustainable energy source, offering economic and environmental benefits through the effective utilization of agricultural waste and reduction of carbon emissions.
  • Thumbnail Image
    Item
    Unraveling the origin of the high photocatalytic properties of earth-abundant TiO2/FeS2 heterojunctions: insights from first-principles density functional theory
    (Physical Chemistry Chemical Physics Journal, 2024) Awe, O.F.; Eya, H.I.; Nbelayim, P.
    Herein, first-principles density functional theory calculations have been employed to unravel the interfacial geometries (composition and stability), electronic properties (density of states and differential charge densities), and charge carrier transfers (work function and energy band alignment) of a TiO2(001)/FeS2(100) heterojunction. Analyses of the structure and electronic properties reveal the formation of strong interfacial Fe–O and Ti–S ionic bonds, which stabilize the interface with an adhesion energy of 0.26 eV Å 2 . The work function of the TiO2(001)/FeS2(100) heterojunction is predicted to be much smaller than those of the isolated FeS2(100) and TiO2(001) layers, indicating that less energy will be needed for electrons to transfer from the ground state to the surface to promote photochemical reactions. The difference in the work func tion between the FeS2(100) and TiO2(001) heterojunction components caused an electron density rearran gement at the heterojunction interface, which induces an electric field that separates the photo-generated electrons and holes. Consistently, a staggered band alignment is predicted at the interface with the conduc tion band edge and the valence-band edge of FeS2 lying 0.37 and 2.62 eV above those of anatase. These results point to efficient charge carrier separation in the TiO2(001)/FeS2(100) heterojunction, wherein photo induced electrons would transfer from the FeS2 to the TiO2 layer. The atomistic insights into the mechanism of enhanced charge separation and transfer across the interface rationalize the observed high photocatalytic activity of the mixed TiO2(001)/FeS2(100) heterojunction over the individual components
  • Thumbnail Image
    Item
    Who is marginalized in energy justice? Amplifying community leader perspectives of energy transitions in Ghana
    (Energy Research & Social Science, 2021) Baker, E.; Nock, D.; Dodoo-Arhin, D.; et al.
    There is a divide in energy access studies, between technologically-focused modeling papers in engineering and economics, and energy justice frameworks and principles grounded in social sciences. Quantitative computational models are necessary when analyzing energy, and more specifically electricity, systems, as they are technologically-complex systems that can diverge from intuitive patterns. To assure energy justice, these models must be reflective of, and informative to, a wide range of stakeholders, including households and communities alongside utilities, governments, and others. Yet, moving from a qualitative understanding of pref erences to quantitative modeling is challenging. In this perspective piece, we pilot the use of the value-focused thinking framework to inform stakeholder engagement. The result is a strategic objective hierarchy that highlights the tradeoffs and the social, economic and technological factors that need to be measured in models. We apply the process in Ghana, using a survey, stakeholder workshops, and follow-up interviews to uncover key tradeoffs and stakeholder-derived ob jectives. We discuss three key areas that have been rarely, if ever, well-represented in energy models: (1) the relationship between the dynamics of electricity end-use and the technology and economic structure of the system; (2) explicit tradeoffs between electricity access, cost, and reliability as defined by stakeholders; and (3) the definition of new objectives, such as minimizing hazards related to theft. We conclude that this model of engagement provides an opportunity to tie together rigorous qualitative analysis and stakeholder engagement with crucial quantitative models of the electricity system.
  • Thumbnail Image
    Item
    Multicomponent Photocatalytic-Dispersant System for Oil Spill Remediation
    (ACS Omega, 2024) Gbogbo, S.; Nyankson, E.; Agyei-Tuffour, B.; et al.
    In the present work, the potential application of a fabricated halloysite nanotubes-Ag-TiO2 (HNT-Ag-TiO2) compo site loaded with a binary surfactant mixture made up of lecithin and Tween 80 (LT80) in remediating oil spillages was examined. The as-prepared Ag-TiO2 that was used in the fabrication of the HNT-Ag-TiO2-LT80 composite was characterized by X-ray diffraction, Raman spectroscopy, UV−vis and diffuse reflectance spectroscopy, CV analyses, and SEM-EDX. The synthesized composite was also characterized by thermogravimetric analysis, Fourier-transform infrared spectroscopy, and scanning electron microscopy-energy dispersive X-ray spectroscopy. The synthesized composite was active in both the UV and visible light regions of the electromagnetic spectrum. The oil-remediating potential of the as-prepared composite was examined on crude oil, and aromatics and asphaltene fractions of crude oil. The composite was able to reduce the surface tension, form stable emulsions and smaller oil droplet sizes, and achieve a high dispersion effectiveness of 91.5%. A mixture of each of the crude oil and its fractions and HNT-Ag-TiO2-LT80 was subjected to photodegradation under UV light irradiation. The results from the GC-MS and UV−vis analysis of the photodegraded crude oil revealed that the photocatal composite was able to photodegrade the crude oil, aromatics, and asphaltene fractions of crude oil with the formation of intermediate photodegradation products depicting that the HNT-Ag-TiO2-LT80 has a potential as an oil spill remediation material.
  • Thumbnail Image
    Item
    Recent Trends in The Use of Nanomaterials for Wastewater Treatment: A Minireview
    (The 2nd International Conference on Multidisciplinary Engineering and Applied Sciences, 2023) Saliu, H.; Annan, E.; Bello, A.
    Man’s life depends on water in many ways. Worldwide industrialization and water resource exploitation have accelerated during the past few decades. Heavy metals and other pollutants, including effluent wastewater, are released into water streams as a result of industrial activity all over the world. Due to their toxicity, these contaminants are thought to be hazardous to both man and the environment and lower the quality of water. Even in low concentrations, heavy metals can be extremely harmful to living things. Numerous methods have been investigated for treating wastewater for many years. However, the discipline of nanotechnology has recently shown the world how to solve the issue of wastewater treatment using creative and practical methods.
  • Thumbnail Image
    Item
    Vulcanization kinetics and reinforcement behaviour of natural rubber-carbon black composites Addition of Shea-butter versus aromatic oil as plasticizers
    (Heliyon, 2024) Mensah, B.; Onwona-Agyeman, B.; Nsaful, F.; et.al;
    This work is a comparative study between Shea butter (SB) and treated distillate aromatic extract oil (TDAE) as plasticizers in the vulcanization of natural rubber (NR)- carbon black (CB) vulcanizates (—CB—S—NR—). The plasticized CB—S—NR composites extended scorch (Ts2) and optimum (T90) curing times. The delays in crosslinking reaction were suspected to be due to the increased viscosity (ML) and insulation of the reacting species (NR, CB, Sulfur and other curing aids) by the films of plasticizers. This effect increased the activation energy (Ea (KJ/mol)) for vulcanization. The CB—S—NR— without plasticizer SB (SBO) showed higher ML, crosslinking density index (ΔM), rheological strength (MH) and low cure reversion properties than others. In comparison, the SB-loaded CB-S—NR— composites showed improvement in ML, ΔM, T90, with lower Ea (KJ/mol) than TDAE samples. Also, the SB compounds exhibited higher Young’s modulus Eo (MPa) than SBO and TDAE compounds. For instance, the Eo (MPa) of SB5 was over 7 and 1200 % higher than SBO and STD5, respectively. However, —CB—S—NR— filled with TDAE generally showed higher strength (MPa), attributed to stronger CB-NR interactions. Therefore, environmentally friendly SB could replace petroleum-based oils for compounding rubbers.
  • Thumbnail Image
    Item
    The Use of Recycled Polyethylene in Water-Oil Emulsion for Lightweight Concrete
    (International Journal of Polymer Science, 2024) Nangor, E.; Annan, E.; Konadu, D.S.; Damoah, L.N.W.; et al.
    This study was to determine the suitability of recycled waste polyethylene (WPE) processed into water-oil emulsion for lightweight concrete applications. The processed WPE in the form of polyethylene emulsion (PE-e) is to promote physical interaction between the polymeric material and the cementitious matrix. The PE-e used was also to partially replace concrete mix composition by PE-e_1, PE-e_2.5, PE-e_5, and PE-e_10 percents for reference concrete and to introduce plasticity into the mechanical behaviour of the concrete. The PE was processed into PE-e to promote affinity for water, and this hydrophilicity was prominent in PE-e_1 and PE-e_2.5 percent concretes. Concretes with PE-e_1 and PE-e_2.5 percent formed good miscibility with the cementitious matrix. The density of the PE-e concrete decreased to 13.68% with 10% PE-e at 28 days. The replacement of mix constituents of PE-e_1, PE-e_2.5, and PE-e_5 percent induced elastic to plastic behaviour in the concrete coupled with low water absorption. The FTIR data showed characteristic peaks of 3378 cm-1, 1740 cm-1, and 1148 cm-1 in the PE-e. Using optical microscopy, it was shown that the PE particles were homogenously dispersed in the concrete matrix. The study shows the feasibility of using PE-e_1 percent to produce structural lightweight concrete and up to PE-e_10 percent for nonstructural applications mainly for light, non-load-bearing partitions
  • Thumbnail Image
    Item
    Fracture and Toughening of Mycelium-based Biocomposites
    (Materials & Design, 2024) Etinosa, P.O.; Salifu, A.A.; Osafo, S.; et al.
    This study presents a combined experimental and analytical study of the fracture behavior and toughening mechanisms of bioprocessed mycelium-based biocomposites. The composites comprise hemicellulose hemp ducts (as nutritional and reinforcing components) intertwined with increasing weight percentages of laterite particles. Single-edge notched fracture experiments and in-situ observations of crack growth were used to explore the ef fects of varying proportions of laterite on the composite resistance-curve behavior. The toughening mechanisms, fracture modes, and crack-microstructure interactions were also elucidated. Since crack-bridging and crack deflection were observed to be the dominant toughening mechanisms, they were modeled using fracture me chanics approaches. Crack-bridging was shown to dominate the toughening at lower weight fractions of laterite (0–20 wt%). However, as the laterite content increases (20–40 wt%), a combination of crack-bridging and crack deflection was observed. Finally, at higher laterite weight fractions (>40 wt%), crack-tip shielding occurred primarily via crack deflection. The fracture mechanics predictions of resistance-curve behavior are shown to be consistent with the experimental measurements. The results suggest that mycelium-based and mycelium-laterite composites can be engineered with tunable fracture toughness. The implications of the results are also discussed for the development of sustainable building materials.
  • Thumbnail Image
    Item
    Ultrasonic–biogenic synthesis of silver on anodized aluminum with superior antibacterial properties
    (Materials Advances, 2023) Agbe, H.; Sarkar, D.K.; Dodoo-Arhin, D.; et al.
    The design and fabrication of high-touch surfaces with antibacterial properties can reduce microbial burden and subsequent nosocomial infections in a hygiene-critical environment. In the present study, biogenic silver nanoparticles (biogenic Ag-NPs) have been synthesized and deposited in situ on an anodized aluminum oxide surface using an ultrasound-assisted onion extract synthesis process. Morphological features and chemical composition have been characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) spectroscopy, UV-Vis absorption spectroscopy and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The biogenic Ag-NP-coated anodized aluminum exhibited 100% E. coli bacteria inactivation under 60 minutes of contact
  • Thumbnail Image
    Item
    Chicken Feather Protein Dispersant for Effective Crude Oil Dispersion in the Marine Environment
    (American Chemical Society, 2023) Adofo, Y.K.; Nyankson, E.; Agyei-Tuffour, B.; et al.
    Various studies report that aside from the adverse impact of crude oil on the marine environment, there is the likelihood that chemical dispersants used on the surface of water as oil-treating agents themselves possess a degree of toxicity, which have additional effects on the environment. To eliminate the subject of toxicity, there are several materials in nature that have the ability to form good emulsions, and such products include protein molecules. In In this study, chicken feathers, which are known to contain ≥90% protein, were used to formulate a novel dispersant to disperse crude oil in seawater (35 ppt). Protein from chicken feathers was extracted and synthesized into the chicken feather protein (CFP) dispersant using deionized water as a solvent. Emulsions formed from CFP-synthesized dispersants were stable over a considerably long period of time, whereas the droplet sizes of the emulsion formed were on the average very small in diameter, making droplet coalescence very slow. The CFP dispersants exhibited moderate surface and interfacial activity at normal seawater salinity. Using the US EPA’s baffled flask test, at 800 and 1000 mg/ml CFP surfactant-to-oil ratios, dispersion effectiveness values of 56.92 and 68.64 vol % were obtained, respectively, which show that CFP has a great potential in crude oil dispersion. Moreover, the acute toxicity test performed on Nile tilapia showed that CFP was practically nontoxic with an LC50 value of more than 100 mg/L after 96 hours of exposure. The results obtained showed that the CFP dispersant is environmentally friendly.