Uranium (U) exhibits a high temperature body-centered cubic (bcc) allotrope that is often stabilized by alloying with transition metals such as Zr, Mo, and Nb for technological applications. One such application involves U–Zr as nuclear fuel, where radiation damage and diffusion (processes heavily dependent on point defects) are of vital importance. Metallic nuclear fuels swell under fission conditions, creating fission product gases such as helium, xenon and krypton. Several systems of U are examined within a density functional theory framework utilizing projector augmented wave pseudopotentials. The bulk modulus, the lattice constant, and the Birch–Murnaghan equation of state for the defect free bcc uranium allotrope are calculated. Defect parameters calculated include energies of formation of vacancies in the α and γ allotropes, as well as self-interstitials, Zr, He, Xe and Kr interstitial and substitutional defects. This work is utilized in the construction of modified Embedded-Atom Method interatomic potentials for the bcc phase of uranium as well as the binary systems of U-Xe, U-Kr and U-He. Using this potential, equilibrium volume and elastic constants are calculated at 0 K and found to be in close agreement with previous first principles calculations. Further, the melting point, heat capacity, enthalpy of fusion, thermal expansion and volume change upon melting are calculated and found to be in reasonable agreement with experiment. Calculations of dilute fission gas defects show reasonable agreement with first principles calculations. Finally, void and xenon bubble energetics are analyzed as a function of temperature.

Rapidly increasing concerns about energy security coupled with detrimental environmental impacts posed by the dependence on fossil fuels, and an urgent need for rural development in Africa are key drivers for the search for fuel alternatives. The international effort into the development of criteria and indicators for sustainable bioenergy production clearly recognizes that bioenergy production must not be at the expense of biodiversity and food security. Owing to its multi-purpose capabilities i.e. its ability to rehabilitate eroded lands, drought resistance as well as its biophysical and maintenance requirements, Jatropha was selected as a potential candidate for the production of biodiesel. Jatropha is not new to the people of Tanzania, the study area of the project. Research has shown that, its associated social, environmental and economic benefits are crucial to economic development of the country. At present, all of Tanzania’s petroleum based products are imported; about 90% of the energy consumed is derived from biomass; road, rail and electricity networks are underdeveloped. Environmental degradation is also a concern in the country. The aim of the study was to identify three optimal locations for large scale Jatropha cultivation for biodiesel production in Tanzania’s semi arid regions. Geographical Information Systems was used to overlay several remotely sensed data from previous research namely semi arid regions delineations, agro-ecological sub-zones that had Jatropha potential as well as the administrative zones of Tanzania. The unavailable and/unsuitable areas were verified against literature and this enabled the areas that were under cultivation, were housing biodiversity or were generally constrained to be filtered out from the study area. The three largest, available and potentially suitable areas that the study identified for large scale Jatropha cultivation occupied about 7.6 million hectares. Assuming an optimal seed yield and an oil content of 35%, these areas are capable of producing about 14.4 million litres of Jatropha oil per annum. Targeting a SADC fuel import substitution of 10%, these 14.4 million litres of Jatropha oil that the three areas will meet about 83% of the country’s energy needs. Owing to the state of electricity generation in Tanzania, these three areas are able to generate about six percent of electricity and this can contribute to some extend to the country energy needs. From the analysis it was clear to note that the production of biodiesel for blending or for electricity generation is going to be economically viable from the three selected regions. The available and suitable areas that were not consolidated within the three selected regions can be used for small scale Jatropha cultivation and their produce can be fed to large scale commercial oil production or they can use the biodiesel to produce their own electricity. Jatropha will have to be irrigated to enhance a viable economic yield; infrastructure will need to be constructed to areas that are not served by roads and railway lines. All of this bodes well for enhancing rural development. The government has already had the foresight to establish the National Biofuels Task Force which will need to monitor investors to ensure no enforced human displacement and/or exploitation in areas where the large scale farms are to be established. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2009.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: van Rooijen, Wilfred; Committee Member: Hertel, Nolan; Committee Member: Stacey, Weston

Thesis (M. Sc.)--University of Hong Kong, 1998. / Company products' information leaflets inserted. Includes bibliographical references.

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Thesis (Master of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, 2018. / The production of biodiesel is an energy and water intensive process. The wastewater that is produced during this process is high in concentrations of COD, BOD, FOG and various other contaminants. Since it contains low levels of nutrients, it is difficult to degrade using natural processes such as conventional activated sludge wastewater treatment. The discharge of untreated biodiesel wastewater also raises serious environmental concern. It interferes when remediated with biological processes and results in additional costs during the production of biodiesel when penalties and fines are applied. Conventional treatment processes are not capable of treating contaminants and pollutants in biodiesel to satisfactory concentrations and hence advanced treatment processes are necessary. In this research, a lab scale integrated treatment process was used to investigate the successful reduction of contaminants, in particular COD, BOD and FOG. The integrated treatment process used in this study consisted of three consecutive steps; acidification, electrochemical oxidation and adsorption using chitosan as an adsorbent. The electrochemical oxidation process with IrO2-Ta2O5/Ti anodes was applied to treat biodiesel wastewater. Different operating conditions were tested to establish favourable conditions. The current density applied as well as the concentration of NaCl as the supporting electrolyte greatly affected the process. A NaCl concentration of 0.08M was deemed sufficient, whereas a current density of 1 mA/cm² showed superior performance compared to lower or higher current densities. Adsorption of pollutants in biodiesel wastewater was investigated using Chitosan as the adsorbent. Various chitosan concentrations, initial pH of the wastewater and repetitive adsorption stages were investigated. It was discovered that all three operating conditions greatly affect the performance of the process. The three consecutive adsorption stages using a chitosan concentration of 4.5 g/L at a pH of 2 resulted in the highest pollutant removal. It was observed that the integrated treatment process could reduce COD, BOD and FOG levels by 94%, 86% and 95% respectively. This concludes that the treated effluent complies with local industrial effluent discharge standards, which could be disposed safely without further treatment.

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