published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

This study utilizes new geochemical analyses of fluids (formation water and gas) collected predominately from Devonian organic-rich shales and reservoir sandstones from the northern Appalachian Basin margin to investigate basin scale hydrologic processes, water-rock reactions, microbial activity, and natural gas generation. Elemental and isotopic composition of co-produced formation waters and natural gas show that the majority of methane in Devonian organic-rich shales and reservoir sandstones is thermogenic in origin with localized accumulations of microbial gas. Microbial methanogenesis appears to be primarily limited by redox buffered conditions favoring microbial sulfate reduction. Thermal maturity (bioavailability) of shale organic matter and the paucity of formation waters may also explain the lack of extensive microbial methane accumulations. Iodine and strontium isotopes, coupled to elemental chemistry demonstrate basin scale fluid flow and clay mineral diagenesis. Evidence for this is based on anomalously high ¹²⁹I/I values sourced from uranium deposits (fissiogenic production of ¹²⁹I) at the structural front of the Appalachian Basin. Radiogenic ⁸⁷Sr/⁸⁶Sr (up to 0.7220), and depleted boron and potassium concentrations support smectite clay diagenesis at temperatures greater than 120 °C. The development of fissiogenic ¹²⁹I as a tracer of basin scale fluid flow is a novel application of iodine isotopes provided that the sources of cosmogenic and anthropogenic ¹²⁹I are reasonably well constrained. The anomalously high ¹²⁹I/I in Appalachian Basin brines may be alternatively explained by microbial fractionation based on a correlation with decreasing δ¹³C-DIC values and decreasing sulfate concentrations in the range of sulfate reduction. These results demonstrate that the microbial fractionation of iodine isotopes may be possible and an important consideration when interpreting ¹²⁹I/I, regardless of the source of ¹²⁹I. Results from this study have important implications for understanding the controls on and origins of natural gas production in sedimentary basins; tectonically and topographically driven basin scale fluid flow, including diagenetically induced waterrock reactions and mineral ore deposition related to orogenesis; and an improvement of the use of iodine isotopes for understanding large scale fluid flow, and possibly its use as a tracer of organic matter diagenesis and the distribution of radionuclides in the environment.

The demand for energy is increasing throughout the world, and fossil fuel resources are diminishing. At the same time, the use of fossil fuels is slowly being reduced because it pollutes the environment. Research into alternative energy sources becomes necessary and important. An alternative fuel should not only replace fossil fuels but also address the environmental challenges posed by the use of fossil fuels. Hydrogen is an environmentally friendly substance considering that its product of combustion is water. Hydrogen is perceived to be a major contender to replace fossil fuels. Although hydrogen is not an energy source, it is an energy storage medium and a carrier which can be converted into electrical energy by an electrochemical process such as in fuel cell technology. Current hydrogen production methods, such as steam reforming, derive hydrogen from fossil fuels. As such, these methods still have a negative impact on the environment. Hydrogen can also be produced using thermochemical cycles which avoid the use of fossil fuels. The production of hydrogen through thermochemical cycles is expected to compete with the existing hydrogen production technologies. The sulphur iodine (SI) thermochemical cycle has been identified as a high-efficiency approach to produce hydrogen using either nuclear or solar power. A sound foundation is required to enable future construction and operation of thermochemical cycles. The foundation should consist of laboratory to pilot scale evaluation of the process. The activities involved are experimental verification of reactions, process modelling, conceptual design and pilot plant runs. Based on experimental and pilot plant data presented from previous research, this study presents the simulation of the sulphur iodine thermochemical cycle as applied to the South African context. A conceptual design is presented for the sulphur iodine thermochemical cycle with the aid of a process simulator. The low heating value (LHV) energy efficiency is 18% and an energy efficiency of 24% was achieved. The estimated hydrogen production cost was evaluated at $18/kg. / Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2012.

The demand for energy is increasing throughout the world, and fossil fuel resources are diminishing. At the same time, the use of fossil fuels is slowly being reduced because it pollutes the environment. Research into alternative energy sources becomes necessary and important. An alternative fuel should not only replace fossil fuels but also address the environmental challenges posed by the use of fossil fuels. Hydrogen is an environmentally friendly substance considering that its product of combustion is water. Hydrogen is perceived to be a major contender to replace fossil fuels. Although hydrogen is not an energy source, it is an energy storage medium and a carrier which can be converted into electrical energy by an electrochemical process such as in fuel cell technology. Current hydrogen production methods, such as steam reforming, derive hydrogen from fossil fuels. As such, these methods still have a negative impact on the environment. Hydrogen can also be produced using thermochemical cycles which avoid the use of fossil fuels. The production of hydrogen through thermochemical cycles is expected to compete with the existing hydrogen production technologies. The sulphur iodine (SI) thermochemical cycle has been identified as a high-efficiency approach to produce hydrogen using either nuclear or solar power. A sound foundation is required to enable future construction and operation of thermochemical cycles. The foundation should consist of laboratory to pilot scale evaluation of the process. The activities involved are experimental verification of reactions, process modelling, conceptual design and pilot plant runs. Based on experimental and pilot plant data presented from previous research, this study presents the simulation of the sulphur iodine thermochemical cycle as applied to the South African context. A conceptual design is presented for the sulphur iodine thermochemical cycle with the aid of a process simulator. The low heating value (LHV) energy efficiency is 18% and an energy efficiency of 24% was achieved. The estimated hydrogen production cost was evaluated at $18/kg. / Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2012.

The fortification of salt with iron may reduce the prevalence of iron deficiency globally, but fortification is complicated by iron-iodiate interactions. To minimize this interaction, a spray dry microencapsulation system was developed. This study evaluated the creation and use of this system, and produced engineered iron premixes for integration into coarse iodized salt. Bioavailable ferrous fumarate powders were encapsulated to produce small particles (<20μm). Feed systems containing both suspended and dissolved ferrous fumarate were compared to find optimal conditions. The premixes were blended into iodized salt at 1000ppmiron and stored at 40C, ~60%RH. The salt was sampled periodically for 6 months to evaluate iodine stability. All encapsulated samples showed increased stability. The capsules ability to adhere to the salt as well as its colour and apparent bioavailability were evaluated. The evaluated samples indicate that stable double-fortified salt based on inexpensive, coarse, unrefined salt may be obtained economically by this approach.

Micronutrient poor diets around the globe and in particular in the developing world cause deficiencies in iron and folic acid. This may be rectified by the incorporation of these micronutrients into currently running salt iodization processes. The objective of this project was to develop folic acid and iodine spray solutions to be ready for pilot scale testing and to investigate the stability of triple fortified salt containing iodine, folic acid and microencapsulated ferrous fumarate. The optimal spray solutions were buffered to pH 9 with a carbonate/bicarbonate buffer to stabilize folic acid and contained 1%-2% w/v folic acid and 1%-3% w/v iodine (as KIO3). They remained in solution and retained ≥80% of both micronutrients after 5 months of storage at 25ºC and 45ºC. Double fortified salt produced using these spray solutions retained 100% of both folic acid and iodine over a 5 month period when stored at ambient conditions. Unfortunately triple fortified salt did not sufficiently retain the micronutrients due to excess moisture absorption and inadequate encapsulation of iron.

The fortification of salt with iron may reduce the prevalence of iron deficiency globally, but fortification is complicated by iron-iodiate interactions. To minimize this interaction, a spray dry microencapsulation system was developed. This study evaluated the creation and use of this system, and produced engineered iron premixes for integration into coarse iodized salt. Bioavailable ferrous fumarate powders were encapsulated to produce small particles (<20μm). Feed systems containing both suspended and dissolved ferrous fumarate were compared to find optimal conditions. The premixes were blended into iodized salt at 1000ppmiron and stored at 40C, ~60%RH. The salt was sampled periodically for 6 months to evaluate iodine stability. All encapsulated samples showed increased stability. The capsules ability to adhere to the salt as well as its colour and apparent bioavailability were evaluated. The evaluated samples indicate that stable double-fortified salt based on inexpensive, coarse, unrefined salt may be obtained economically by this approach.

Micronutrient poor diets around the globe and in particular in the developing world cause deficiencies in iron and folic acid. This may be rectified by the incorporation of these micronutrients into currently running salt iodization processes. The objective of this project was to develop folic acid and iodine spray solutions to be ready for pilot scale testing and to investigate the stability of triple fortified salt containing iodine, folic acid and microencapsulated ferrous fumarate. The optimal spray solutions were buffered to pH 9 with a carbonate/bicarbonate buffer to stabilize folic acid and contained 1%-2% w/v folic acid and 1%-3% w/v iodine (as KIO3). They remained in solution and retained ≥80% of both micronutrients after 5 months of storage at 25ºC and 45ºC. Double fortified salt produced using these spray solutions retained 100% of both folic acid and iodine over a 5 month period when stored at ambient conditions. Unfortunately triple fortified salt did not sufficiently retain the micronutrients due to excess moisture absorption and inadequate encapsulation of iron.

Thesis (Ph. D.)--McMaster University (Canada), 1990. / Source: Dissertation Abstracts International, Volume: 62-13, Section: A, page: 0000.

Thesis (M.Sc. (Food and Nutrition for Development))--Mahidol University, 2008. / LICL has E-Thesis 0036 ; please contact computer services.