Theses

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Photocatalytic degradation of Rhodamine dyes using zinc oxide nanoparticles
(Materials Today: Proceedings, 2020) Dodoo-Arhin, D.; Asiedu, T.; Agyei-Tuffour, B.; et al.
This paper presents the synthesis of nanocrystalline zinc oxide (ZnO) particles via the sol-gel method using zinc acetate as a precursor. The calcination temperature of the ZnO was varied to determine its effect on particle size. The resultant samples were characterized using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), UltraViolet–visible Spectroscopy (UV–Vis) and Scanning Electron Microscopy (SEM). Nanocrystalline wurtzite ZnO particles with crystallite sizes ranging from 16 nm to 30 nm were produced. The Energy Band gap of the synthesized zinc oxide nanoparticles decreased with increasing calcination temperature and crystallite size. SEM Micrographs showed rice-like microstructure morphology of ZnO nanoparticles. The usage of the ZnO nanoparticles as a photocatalyst was also explored in the degradation of Rhodamine B dye using UV light, with particular attention paid to the effect of particle size and catalyst load on the degradation efficiency of the dyes. The nanoparticles calcined at 400 C with a crystallite size of 16 nm resulted in the highest degradation efficiency of 95.41% when 0.2 g catalyst loading was applied. 2019 Elsevier Ltd. All rights reserved. Selection and peer review under the responsibility of the scientific committee of the International Symposium on Nanostructured, Nanoengineered, and Advanced Materials
Modified nanostructured titania photocatalysts for aquatic disinfection applications
(Materials Today: Proceedings, 2020) Dodoo-Arhin, D.; Bowen-Dodoo, E.; Agyei-Tuffour, B.; et al.
According to SDG 6, everyone on earth should have access to safe and affordable drinking water. In sharing water-treatment technologies that lead to accomplishing this goal, it is imperative to devise ways of removing microbial contaminants such as E. coli from drinking water, especially in resource-limited settings that lack centralized water supply systems. One of the approaches is bacterial disinfection of water at the point of use. In this study, the bactericidal effects of the photocatalysis of titanium dioxide-based nanoparticles under UV and visible light are explored. Pristine and silver doped nanostructured mesoporous titanium dioxide (Ag-TiO2, TiO2) particles with high specific surface area and average crystallite domain size of 7.0–7.5 nm were prepared using the simple and cost-effective sol-gel technique followed by thermal treatment. The addition of Ag+ ions during the hydrolysis/condensation of the Ti(IV) molecular precursor led to the homogeneous dispersion of the Ag+ cations on the titania matrix. The As-prepared nanoparticles were characterized using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), thermogravimetry, Fourier Transform Infra-Red (FTIR), and Raman Spectroscopy. X-ray diffraction, FTIR, and Raman spectroscopy confirmed that the crystalline structure of the TiO2 matrix corresponds to the anatase polymorph; however, the presence of the dopant led to an increase in the system disorder due to the rise in the concentration of oxygen vacancies. The As-prepared nanoparticles were used for Escherichia coli (E. coli) inactivation under dark and UV–visible light conditions. Under dark conditions, Ag-doped titania and pristine titania resulted in 95% and 64% E. coli population inactivity while under light conditions, 99% and 97% degradation respectively were observed. Taken together, these results demonstrate that, the synthesized TiO2 nanoparticles have promising applications in the light-mediated point-of-use inactivation of bacterial contaminants in water. 2019 Elsevier Ltd. All rights reserved. Selection and peer review under the responsibility of the scientific committee of the International Symposium on Nanostructured, Nanoengineered, and Advanced Materials.
Mechanical measurements of pure and kaolin reinforced hydroxyapatite-derived scaffolds: A comparative study
(Materials Today: Proceedings, 2020) Obada, D.O.; Dodoo-Arhin, D.; Dauda, E.T.; et al.
This study describes the mechanical properties of pure hydroxyapatite (HAp) and kaolin-reinforced hydroxyapatite (K-HAp) is produced from non-separated animal bones using compression pressure under different sintering regimes. The HAp microparticles were synthesized separately using a facile heat treatment method and reinforced with 15 wt% of beneficiated kaolin (HAp/15 wt% BK) using the sol-gel method. The HAp and K-HAp-derived scaffolds were fabricated by cold pressing with a compaction pressure of 500 Pa. Next, the scaffolds were sintered at 900 C, 1000 C, and 1100 C with a 2 h dwell time in the air atmosphere. Subsequently, the mechanical properties of the scaffolds were examined. The effect of sintering temperature and compaction pressure on the hardness and the compressive strength of the pure and reinforced HAp showed that at all points of measurement (with and without compaction pressure), the mechanical properties increased with an increase in sintering temperature, and the most significant mechanical properties were obtained at 1100 C. The values of hardness at the maximum sintering temperature (1100 C) are 0.93 and 1.09 GPa with and without the application of compaction pressure, respectively, for pure HAp-derived scaffolds and 0.74 and 0.78 GPa with and without the application of compaction pressure, for K-HAp-derived scaffolds. The compressive strength for K HAp had the value of 7.84 MPa as compared with 0.69 MPa for the non-reinforced HAp matrix with the application of compaction pressure (500 Pa). The findings show that the mechanical properties of the synthesized kaolin-reinforced HAp about the scaffolds produced with the low compaction pressure of 500 Pa are suitable for human trabecular bone. 2020 The Authors. Published by Elsevier Ltd. This is an open-access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by nc-and/4.0) Selection and Review under the responsibility of the scientific committee of the International. Conference & Exposition on Mechanical, Material, and Manufacturing Technology.

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