This study introduces an evaluation of the downstream utilization of oxygen produced by the hybrid sulfur process (HYS). Both technical and economic aspects were considered in the production of primarily synthesis gas and hydrogen. Both products could increase the economic potential of the hybrid sulfur process. Based on an assumed 500MWt pebble bed modular nuclear reactor, the volume of hydrogen and oxygen produced by the scaled down HYS was found to be 121 and 959 ton per day respectively. The partial oxidation plant (POX) could produce approximately 1840 ton synthesis gas per day based on the oxygen obtained from the HYS. The capital cost of the POX plant is in the order of $104 million (US dollars, Base year 2008). Compared to the capital cost of the HYS, this seems to be a relatively small additional investment. The production cost varied from a best case scenario $9.21 to a worst case scenario of $19.36 per GJ synthesis gas. The profitability analysis conducted showed favourable results, indicating that under the assumed conditions, and with 20 years of operation, a NPV of $87 mil. and an IRR of 19.5% could be obtained, for the assumed base case. The economic sensitivity analysis conducted, provided insight into the upper and lower limitations of favourable operation. The second product that could be produced was hydrogen. With the addition of a water gas shift and a pressure swing adsorption process to the POX, it was found that an additional 221 ton of hydrogen per day could be produced. The hydrogen could be produced in the best case at $2.34/kg and in the worst case at $3.76/kg. The investment required would be in the order of $50 million. The profitability analysis for the base case analysis predicts an NPV of $206 million and a high IRR of 23.0% under the assumed conditions. On financial grounds it therefore seemed that the hydrogen production process was favourable. The thermal efficiency of the synthesis gas production section was calculated and was in good agreement with that obtained from literature. The hydrogen production section’s thermal efficiency was compared to that of steam methane reforming of natural gas (SMR) and it was found that the efficiencies were comparable but the SMR process was superior. The hydrogen production capacity of the HYS process was increased by a factor of 1.83. This implied that for every 1 kg of hydrogen produced by the HYS an additional 1.83 kg was produced by the proposed process addition. This lowers the cost of hydrogen produced by the HYS from $6.83 to the range of approximately $3.93 - $4.85/kg. In the event of a global hydrogen economy, traditional production methods could very well be supplemented with new and innovative methods. The integration of the wellknown methods incorporated with the new nuclear based methods of hydrogen production and chemical synthesis could facilitate the smooth transition from fossil fuel based to environmentally friendly methods. This study presents one possible integration method of nuclear based hydrogen production and conventional processing methods. This process is technically possible, efficient and economically feasible. / Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2009.

The gradual depletion of and dependence on fossil fuels, air pollution and global warming have all accelerated the development of alternative energy systems which use hydrogen as an energy carrier. The hybrid sulphur cycle (HyS) is the foremost electrothermochemical process that can produce hydrogen as the energy carrier. The HyS cycle consists of two units, namely the sulphuric acid decomposition reactor and the sulphur dioxide electrolyser (SDE). The SDE is responsible for the SO2 electrooxidation to sulphuric acid and protons at the anode and the electro–reduction of protons to hydrogen at the cathode. This research study focuses on the kinetic data collected from the prepared catalysts for SO2 electro–oxidation at the anode. Platinum dispersed on carbon, niobium pentoxide, tantalum pentoxide and zirconium dioxide as electrocatalysts were prepared using sodium borohydride as a reducing agent. These electrocatalysts were characterized using transmission electron microscopy and x–ray diffraction. Cyclic voltammetry was used to study the electrochemical active surface area (EAS) and the results showed that Pt/ZrO2–C had a higher EAS area than Pt/Ta2O5–C, Pt/Nb2O5–C and Pt/C. The high EAS of Pt/ZrO2–C can be explained by the low crystal size however after a series of linear polarisation scans Pt/ZrO2–C experiences a much greater area loss than all the other catalysts. Linear polarisation scans for each of the catalysts revealed that the influence of increased temperature and sulphuric acid concentration were showed improved results. Levich and Koutecky–Levich plots revealed that the SO2 oxidation is a multistep reaction on all the prepared catalysts and that there are regions which are kinetic and diffusion controlled and diffusion–only controlled. Pt/Ta2O5–C catalysts exhibited superior catalytic activity and stability compared Pt/Nb2O5–C, Pt/ZrO2–C and Pt/C. The Pt/ZrO2–C exhibited the most inferior catalytic activity and stability. / Thesis (M.Sc. (Chemistry))--North-West University, Potchefstroom Campus, 2011.

The ever increasing global demand for materials has placed aluminium as the world’s second most used metal, with world annual production currently >24 million tons. Consequently, the global alumina industry is perpetually striving to meet demands in conjunction with research, development and implementation of more efficient and sustainable processes and practises. Of specific concern for many proponents within the industry is that increased alumina production inadvertently results in increased Bayer Process-derived alkaline solid and liquid waste loads. Furthermore, in-house power generation at all Australian alumina refineries contributes to acid gas emissions, particularly SOx and NOx, both of which have environmental and anthropogenic impacts of global concern. The focus of this work is SO2 emission. SOx emission control measures can be achieved before, during or after combustion; the latter is termed flue gas desulphurisation (FGD). Commercially available FGD systems are dominated by once-through wet processes whereby the flue gas passes up through an absorbtion tower. The most favourable medium for industrial use is seawater, followed by limestone, and in some cases, a combination of both. However, the ever-increasing stringency of environmental emission legislation continues to inflict tighter controls on power production and is forcing industry to investigate alternative cost-effective FGD mediums. Therefore much research is currently dedicated to the utilisation of high volume, alkaline waste streams over manufactured sorbents. Modern environmental engineering approaches to waste product minimisation, neutralisation and/or reuse have lead to many new processes which change the view of many materials from waste product to environmental resource. Subsequently, this work examines the application of an isolated Bayer Process waste product, tricalcium aluminate hexahydrate (TCA6), as a FGD medium. Initial research assessed the dissolution behaviour and performance of the proposed medium with sulphuric acid, followed by batch reactor trials with a simulated flue gas. Data derived from this research indicated the suitability of TCA6 as a FGD medium and was subsequently applied to a preliminary model and proposed design parameters required for further pilot scale investigations. This work provides strong support for an economically viable and more sustainable approach to FGD for the alumina industry.

The ever increasing global demand for materials has placed aluminium as the world’s second most used metal, with world annual production currently >24 million tons. Consequently, the global alumina industry is perpetually striving to meet demands in conjunction with research, development and implementation of more efficient and sustainable processes and practises. Of specific concern for many proponents within the industry is that increased alumina production inadvertently results in increased Bayer Process-derived alkaline solid and liquid waste loads. Furthermore, in-house power generation at all Australian alumina refineries contributes to acid gas emissions, particularly SOx and NOx, both of which have environmental and anthropogenic impacts of global concern. The focus of this work is SO2 emission. SOx emission control measures can be achieved before, during or after combustion; the latter is termed flue gas desulphurisation (FGD). Commercially available FGD systems are dominated by once-through wet processes whereby the flue gas passes up through an absorbtion tower. The most favourable medium for industrial use is seawater, followed by limestone, and in some cases, a combination of both. However, the ever-increasing stringency of environmental emission legislation continues to inflict tighter controls on power production and is forcing industry to investigate alternative cost-effective FGD mediums. Therefore much research is currently dedicated to the utilisation of high volume, alkaline waste streams over manufactured sorbents. Modern environmental engineering approaches to waste product minimisation, neutralisation and/or reuse have lead to many new processes which change the view of many materials from waste product to environmental resource. Subsequently, this work examines the application of an isolated Bayer Process waste product, tricalcium aluminate hexahydrate (TCA6), as a FGD medium. Initial research assessed the dissolution behaviour and performance of the proposed medium with sulphuric acid, followed by batch reactor trials with a simulated flue gas. Data derived from this research indicated the suitability of TCA6 as a FGD medium and was subsequently applied to a preliminary model and proposed design parameters required for further pilot scale investigations. This work provides strong support for an economically viable and more sustainable approach to FGD for the alumina industry.

The ever increasing global demand for materials has placed aluminium as the world’s second most used metal, with world annual production currently >24 million tons. Consequently, the global alumina industry is perpetually striving to meet demands in conjunction with research, development and implementation of more efficient and sustainable processes and practises. Of specific concern for many proponents within the industry is that increased alumina production inadvertently results in increased Bayer Process-derived alkaline solid and liquid waste loads. Furthermore, in-house power generation at all Australian alumina refineries contributes to acid gas emissions, particularly SOx and NOx, both of which have environmental and anthropogenic impacts of global concern. The focus of this work is SO2 emission. SOx emission control measures can be achieved before, during or after combustion; the latter is termed flue gas desulphurisation (FGD). Commercially available FGD systems are dominated by once-through wet processes whereby the flue gas passes up through an absorbtion tower. The most favourable medium for industrial use is seawater, followed by limestone, and in some cases, a combination of both. However, the ever-increasing stringency of environmental emission legislation continues to inflict tighter controls on power production and is forcing industry to investigate alternative cost-effective FGD mediums. Therefore much research is currently dedicated to the utilisation of high volume, alkaline waste streams over manufactured sorbents. Modern environmental engineering approaches to waste product minimisation, neutralisation and/or reuse have lead to many new processes which change the view of many materials from waste product to environmental resource. Subsequently, this work examines the application of an isolated Bayer Process waste product, tricalcium aluminate hexahydrate (TCA6), as a FGD medium. Initial research assessed the dissolution behaviour and performance of the proposed medium with sulphuric acid, followed by batch reactor trials with a simulated flue gas. Data derived from this research indicated the suitability of TCA6 as a FGD medium and was subsequently applied to a preliminary model and proposed design parameters required for further pilot scale investigations. This work provides strong support for an economically viable and more sustainable approach to FGD for the alumina industry.

In order to understand, more fully, some of the factors affecting the S requirements of pastures, S³⁵-labelled gypsum fertilizer was applied to several field trials located on soils within the recent, yellow brown earth and high country yellow brown earth soil groups in Canterbury, New Zealand. Among the major processes studied were the incorporation of the S³⁵-labelled gypsum fertilizer into the soil organic matter, its movement in the soil and its uptake by pasture plants. The results obtained showed that on the same soil type, plant uptake of fertilizer S and its incorporation into the organic matter were greater under improved pastures. However, the movement of fertilizer S was relatively unaffected by the pastoral improvement. Rainfall conditions affected all three processes studied, particularly the downward movement of fertilizer S. Over the growing seasons of the first year almost all of the added fertilizer S remained within the upper 15 cm of the soil at a low rainfall trial. On a similar textured soil, receiving almost twice as much rainfall over a similar time period, fertilizer S was distributed evenly to a depth of 60 cm. Where the rainfall was similar, but soils differed in their water holding capacity, large differences in the downward movement of fertilizer S occurred. On a steepland yellow brown earth soil almost 70% of the applied fertilizer S was lost from the 0-45 cm soil depth two months after application. While on a recent soil, with a much higher water holding capacity, greater amounts of fertilizer S remained within the upper 45 cm over the same period.. Large differences in the downward movement of fertilizer S were shown by soils with contrasting retention capacities, but under similar rainfall conditions. On a yellow brown earth soil, with a medium S retention in the subsoil, fertilizer S was found not to have moved beyond 60 cm in the winter following the spring application. In contrast, fertilizer S penetrated beyond the 60 cm on a recent low S retentive soil. Under improved pastoral conditions, applying fertilizer S in late spring rather than early spring, to two different soils gave larger (almost twofold) residual effects the following year. Total recovery of the added fertilizer S in the soil-plant systems studied were generally greater than 80%. The pattern and rate of the downward movement of fertilizer S was little affected by fertilizer rates. Pasture recovery (%) of fertilizer S at the lower rate (22.5 kgS/ha) was slightly higher than that at the higher rate (45 kgS/ha). Fertilizer rates did not produce a consistent effect on the extent of fertilizer S incorporation into soil organic matter. The magnitude of the sulphur cycling pool was determined at each trial location by using the equilibrium specific activity of pasture. This pool was found to vary between trials and showed no relationship to their respective S response patterns. The rate of S cycling appeared to be more important. At some trials a strong correlation was found between the specific activity of the S in pasture and that for phosphate-extractable sulphate in particular soil depths. This relationship was used to assess indirectly, the likely soil zones from which plants extract S to meet their nutritional requirements. A new technique was developed to study, directly, the soil zone from which plants extract S to meet their-nutritional requirements. Carrier-free S³⁵, injected horizontally into various soil depths in a recent and a yellow brown earth soil, showed that both grasses and clovers recovered S³⁵ to a depth of 52 cm, in the spring. However, most of the S³⁵ uptake by plants was found to occur in the upper 30 cm (A horizon) in both soils. In the autumn, S³⁵ uptake experiments on these soils showed uptake to occur at 100 cm on the recent soil, and cease at 52 cm on the yellow brown earth soil. Growth cabinet experiments, using S³⁵-labelled pasture residue, recovered from the field plots, and added to various soils, showed that ryegrass recovery of labelled fertilizer S ranged from 6-16% and it varied according to soil type, degree of pastoral development, type and form of plant residue added. This extent of recovery represents only a small proportion (1%) of the fertilizer S recovered by pasture in the first year. The overall experimental results were considered in relation to both the S response patterns obtained from the present field trials and also those from other similar trials conducted in recent years in the Canterbury area. Some possible reasons for the variable S responses obtained were discussed and methods for improving the efficiency of fertilizer use, at farm level, were proposed.

Onion (Allium cepa L.) is an example of a species that accumulates very high levels of reduced sulfur (S)-containing compounds, particularly in the bulb as alk(en)yl-L-cysteine-sulfoxides (ACSOs) and it is these compounds, or their derivatives, that confers the distinct odour and pungent flavour. In common with higher plants, the S assimilation pathway in onion begins with the activation of uptaken sulfate (SO4 2-) to 5'-adenylylsulfate (APS), a reaction catalysed by ATP sulfurylase (ATPS; EC 2.7.7.4). Then, APS is reduced to sulfide (S2-) in a two-step process catalysed by the enzymes APS reductase (APSR; EC 1.8.4.9) and sulfite reductase (SiR; EC 1.8.7.1). To complete the reductive assimilation pathway, S2- is incorporated into the amino acid skeleton of O-acetylserine (OAS) to form cysteine, and this reaction is catalyzed by OAS (thiol)-lyase (OAS-TL; EC 4.2.99.8). While the regulation of the pathway is quite well defined in the plant model Arabidopsis, much less is known about its regulation in S accumulating species such as onion. The primary aim of this thesis, therefore, was to characterise the enzymes of the S assimilation pathway in onion, with a particular emphasis on ATPS. As part of this charaterisation two genotypes of onion were compared. These comprised a mild genotype, 'Texas Grano 438' (TG) with a lower level of S-containing compounds in the bulb tissues, and 'W202A' (W), a cultivar with a higher level of S containing compounds in the bulb tissues. As well, comparisons were made between seedlings (typically harvested at 7 weeks) and plants at a designated mature stage (at bulbing; typically after 4 months growth), and for plants grown in S-sufficient (S+) media or S-deficicnt (S-) media, as appropriate. In terms of plant growth, S-deprivation generally had a negative influence for both genotypes, with significant reductions in total biomass (measured as fresh weight) for TG at both the seedlings and mature stages. ATPS activity and accumulation were shown to be present in all tissues examined (leaf, root, bulb) as well as the chloroplasts, with highest activity measured in the roots, particularly in seedlings. ATPS activity and accumulation were also compared between the two genotypes (TG and W) with ATPS activity and accumulation higher in W, particularly at the seedling stage. In terms of the influence of S supply, in general higher ATPS activity was measured in chloroplast, leaf and root extracts from plants of both genotypes grown in the S- media, at the seedling stage. In roots of mature plants of both genotypes, a significant increase in activity was measured in response to S-deprivation, while in chloroplasts isolated from mature plants of both genotypes, highest activity was measure in those grown in the S+ media. Finally diurnal variations were observed in chloroplast, leaf and root extracts of both genotypes with a general trend of an increase in ATPS activity and accumulation a few hours after illumination and upon the onset of the dark period. Although a single gene coding for ATPS is presumed to be present in onion, the enzyme was characterized as two electrophoretic forms using 1D-PAGE during western analyses following fractionation of chloroplasts by anion exchange chromatography and also as an alignment of spots using 2D-PAGE. As protease inhibitors were routinely included in the extraction buffers, these forms suggest the occurrence of ATPS isoforms that may arise as a consequence of post-translational modifications. The regulation of ATPS by one mechanism of post-translational modification, phosphorylation, was therefore investigated using several techniques including the detection of a shift in molecular mass, a change in enzyme activity or pI (as determined by 2D-PAGE) and the capability to bind to 14-3-3 proteins using affinity chromatography. Following treatments of chloroplast extracts to promote either the phosphorylation (P+) or the dephosphorylation (P-) of proteins, no molecular mass change or change in activity was observed. However, after fractionation by 2D-PAGE, differences in the spot alignment of ATPS were visualized, suggesting that ATPS is a phosphoprotein. The enzyme was detected in pull-downs after affinity chromatography, suggesting that ATPS may also interact with 14-3-3 proteins (although this needs to be confirmed unequivocally). A model is advanced, therefore, in which upon phosphorylation, no variation in ATPS activity occurs but a change in the surface charged and possibly a change in conformation of the protein does occur to make the enzyme competent to interact with 14-3-3 proteins.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: David R. Maidment. Vita. Includes bibliographical references. Also available from UMI.

Thesis (D. Min.)--New Orleans Baptist Theological Seminary, 1996. / Includes abstract and vita. "March 1996." Includes bibliographical references (leaves 195-201).

Este estudo objetivou avaliar o efeito da aplicação de enxofre (S) e o manejo de nitrogênio (N) em cobertura em relação ao rendimento de grãos e qualidade industrial do trigo. Foram conduzidos três experimentos a campo, na safra de inverno 2013, em Capitão Leônidas Marques, Realeza e Santa Isabel do Oeste, estado do Paraná. Utilizou-se a cultivar de trigo CD 150, semeada em resteva de soja. Foi usado o delineamento experimental de blocos ao acaso com três repetições, em esquema fatorial 3x4. Os tratamentos consistiram de duas fontes de enxofre (gesso agrícola, enxofre elementar pastilhado e testemunha, aplicados a lanço no perfilhamento) e formas de aplicação de nitrogênio em cobertura (100% no perfilhamento, 100% no início da elongação, 50% + 50% e testemunha). As doses utilizadas foram de 80 kg ha-1 de S e N, sendo o nitrogênio aplicado na forma de uréia revestida com inibidor de urease (41% de N). As condições climáticas (precipitação pluviométrica e geadas) observadas na condução dos experimentos resultaram em uma baixa média produtiva geral dos experimentos. Em geral, não houve diferenças significativas entre os manejos de N testados em relação ao rendimento de grãos e índice relativo de clorofila, havendo alta correlação direta entre estas variáveis. O uso de enxofre elementar pastilhado incrementou em 16,3% o rendimento de grãos no ensaio de Realeza, comparado à testemunha. As formas de manejo de N em cobertura influenciaram o teor de glúten úmido (GU) e o índice de elasticidade (IE) da farinha, onde destacou-se a aplicação de N em dose única no início da elongação como melhor manejo. Não observou-se aumento na força de glúten (W) em relação às fontes de enxofre e à aplicação de N em cobertura para a cultivar CD 150. O rendimento de farinha foi influenciado positivamente pelo uso de nitrogênio em cobertura (independente o manejo) e pelas fontes de enxofre aplicadas, com vantagem do enxofre elementar pastilhado em relação ao gesso agrícola. A associação entre caracteres agronômicos e parâmetros de qualidade industrial, indicou que os tratamentos com maiores rendimentos de grãos e que apresentam maiores teores foliares de clorofila são determinantes na obtenção de farinhas com maior GU e IE, porém com tendência a obtenção de menor W e baixa extração de farinha. Assim sendo, para a cultivar de trigo CD 150, uma única aplicação nitrogênio em cobertura no início da elongação, assegura boa produtividade de grãos com benefícios a alguns parâmetros de qualidade industrial do trigo. No entanto, os resultados são inconclusivos em relação à utilização das fontes de enxofre em trigo, em virtude das condições climáticas adversas registradas. Orienta-se a condução de novos ensaios com o enxofre elementar pastilhado usado na adubação de base, o que poderia melhorar sua oxidação junto ao solo. Devem ser conduzidos novos estudos em condições à obtenção de maiores rendimentos de grãos e abrangendo outras cultivares de trigo da classe melhorador. / This study aimed to evaluate the effect of sulfur (S) and the management of nitrogen (N) coverage in relation to grain yield and Wheat industrial quality. Three experiments were conducted in the field, on winter 2013 season, in Captain Leônidas Marques, Realeza and Santa Isabel do Oeste, Paraná state. In all the three places were used the wheat cultivar CD 150, sown in the straw of wheat. We used the experimental of randomized blocks with three replications in a 3x4 factorial design. The treatments consist of two sulfur sources (gypsum and elemental sulfur patched, applied by throwing at tillering, witness) and forms of nitrogen application in coverage (100% at tillering; 100% in the elongation and 50% + 50%, Witness). The doses used are 80 kg ha-1 S and N, being the nitrogen applied in the urea form coated with inhibitor of urease (41% of N). The Weather conditions (rainfall and frost) observed in the conduct of experiments resulted in a general productive low average of experiments. It was observed, in general, no significant differences between the N management tested for grain yield (RG) and relative chlorophyll index (IRC), there is high direct correlation between these variables. The use of elemental sulfur patched increased by 16.3% grain yield testing in Realeza, compared to witness. The forms of management of N in coverage positively influenced the wet gluten content (GU) and the elastic índex (IE) the flour, where stood out the application of N a single dose at the beginning of elongation and better management. There wasn’t have an increase in gluten strength (W) in relation to sources of sulfur and to N coverage for cultivate CD 150. The flour yield was positively influenced by the use of nitrogen in coverage (independent of management) and the applied sulfur sources with the advantage elemental sulfur patched in relation to agricultural plaster. The association between agronomic traits and industrial quality parameters indicated that treatment with higher grain yields and have higher foliar chlorophyll are crucial in obtaining flour with higher GU e IE but with a tendency towards a lower and low extraction flour. Therefore, for the cultivate CD 150 wheat, just one application of nitrogen in coverage in elongation ensures good grain yield benefits to some Wheat quality parameters. However, the results are inconclusive regarding about the use of sulfur sources in wheat, due to adverse weather conditions recorded. The conduction of new tests with elemental sulfur patched used at the base of fertilization is oriented, which could enhance oxidation at ground. Further studies should be conducted in a position to higher grain yields and covering other wheat cultivars enhancer class.