School of Physical and Mathematical Sciences
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Browsing School of Physical and Mathematical Sciences by Author "Amuzu, J.K.A"
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Item Characterization and Source Apportionment of Airborne Particulate Matter in Some Urban Neighbourhoods of Accra, Ghana(University of Ghana, 2014-07) Hughes, A.F.; Kakane, V.C.K.; Amuzu, J.K.A; Agyei, E.K.; University of Ghana, College of Humanities , School of Arts , Department of Philosophy and ClassicsA year-long campaign which accounted for seasonal differences have been conducted to examine the levels, chemical composition and sources of ambient particulate matter in multiple neighbourhoods of varying socio-economic status in Accra, Ghana. Between September 2007 and August 2008, simultaneous measurements of PM2.5 and PM10 aerosols at five monitoring sites in four neighbourhoods (Asylum Down, East Legon, Nima and James Town/Ussher Town) were done for one 48-hour period every six days. Harvard Impactor with polytetrafluorethylene (PTFE) Teflon filter of 37 mm supported by a Whatman drain disc were used to sample air particles in the Accra neighbourhoods. Gravimetric analysis and energy dispersive X-ray fluorescence (EDXRF) were used to determine the chemical composition and concentration of the aerosol particles. The mean mass concentration values for PM2.5 obtained at the five sites during the study period varied from 45.9 μg m-3 to 74.8 μg m-3. The mean mass concentration for PM10 also varied from 93.9 μg m-3 to 134.8 μg m-3. These levels were all substantially higher than the EPA (Ghana) guidelines values and other international air quality standards from WHO, USEPA and EU. Weak relationships were obtained between PM and weather parameters. Crustal elements were most abundant during the seasonal Harmattan period between late December and early February when Saharan dust is transported across West Africa. Enrichment factor analysis was used to provide an initial indication of the species of anthropogenic origin in the measured elemental composition. Source contributions were analysed using positive matrix factorization (PMF) model separately for Harmattan and non-Harmattan periods because large changes to source profiles is expected during the Harmattan period. Anthropogenic sources resolved by PMF model (biomass burning, solid waste burning, resuspended dust and traffic/industry emissions) during both Harmattan and non-Harmattan periods had significant influence on the four neighbourhoods in Accra.Item Synthesis and Characterization of Cupric Oxide Nanoparticles for Photovoltaic Applications(University of Ghana, 2015-03) Yankson, A.A; Kuditcher, A; Amuzu, J.K.A; Hagoss, G.G; University of Ghana, College of Basic and Applied Sciences, School of Physical and Mathematical Sciences, Department of PhysicsA simple inexpensive chemical route has been identified and used to synthesize cupric oxide nanoparticles suitable for photovoltaic applications. X-ray diffraction analysis showed the synthesized nanoparticles to be a pure cupric oxide phase. The particle size and particle size distribution of the cupric oxide nanoparticles were obtained by transmission electron microscopy (TEM) whereas the crystallite size and crystallite size distribution were obtained by X-ray diffraction peak broadening analysis. The particle size was found to be between 20 nm and 60 nm, an indication that cupric oxide nanoparticles are dominant in the sample produced and analysed. The particle size distribution obtained from cumulative percentage frequency plots features a log-normal function. Absorbance measurements and analysis show that the material has an absorbance peak around 314 nm and an average energy bandgap of 1.48 eV, making it a good candidate for photovoltaic applications. A thin film of average thickness of 1.47 microns made, was used to determine the conductivity of the material, which is 8.541×10−2 Ω−1cm−1. Incident radiation of various wavelengths from the highest (600 nm) to the lowest (300 nm), caused decrease in resistance of the thin film sample, an indication that the material responds favourably to visible radiation making it suitable for photovoltaic and photo electronic applications. We emphasize that a low cost approach has been used successfully to synthesize cupric oxide nanoparticles with the suitable optical and electrical properties required for application in the photovoltaic and photo electronic industries.