Synthesis of dimethyl ether using natural gas as a feed via the C-H-O ternary diagram

A dissertation submitted to the faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Science in Engineering – Chemical Engineering Johannesburg, 2017In this research, the C, H and O bond equivalent diagram was used to design processes for DME synthesis using natural gas as a feed. This research proposes alternative ways of producing DME using natural gas (a cleaner gas) compared to the traditional routes. The different feed combinations were assessed for the production of syngas. The crucial step is the H2:CO ratio in each feed which determines the DME synthesis process route and yield. The syngas process was developed under equilibrium and non-equilibrium conditions (assuming 100% methane conversion). The region of operation on the ternary bond diagram was limited by mass and energy balance and carbon deposition boundaries. The feed composition was as follows, (1) Feed 1: methane, steam and oxygen (2) Feed 2: methane, oxygen and carbon dioxide (3) Feed 3: methane, oxygen, carbon dioxide and water. Feed (2) had the highest DME yield. The most optimal reaction route produced DME via the JFE reaction route (H2:CO =1). The yield of DME was 0.67 moles of DME per mole methane processed under non-equilibrium conditions. The proposed route does not emit CO2, excess CO2 is recycled back to the reforming reactor. Under equilibrium, the yield of DME was 0.25 mole DME per mole methane processed. The results indicate that a combination of partial oxidation and dry reforming produces a syngas composition which results in a high DME yield compared to (1) and (3).MT201

KARAKTERISASI KITOSAN DARI CANGKANG KERANG DARAH (Anadara granosa) CHARACTERIZATION CHITOSAN FROM THE SHELLS OF BLOOD CLAMS (Anadara granosa)

Abstrak. Kitosan dapat diisolasi melalui tahap demineralisasi, deproteinasi, dan deasetilasi. Tujuan dari penelitan ini adalah mengetahui karakterisasi kitosan cangkang kerang darah yang menggunakan enzim papain pada proses deproteinasi. Pada tahap deproteinasi dilakukan variasi jumlah enzim dan waktu inkubasi untuk memperoleh kadar nitrogen terendah yang ditentukan melalui metode Kjeldahl. Karakterisasi kitosan yang dilakukan meliputi kadar air, kadar abu serta analisis gugus fungsi menggunakan spektroskopi FTIR. Hasil karakterisasi kitosan diperoleh kadar air sebesar 1,16%, kadar abu 1,25%, derajat deasetilasi 91,7% serta memiliki gugus fungsi kitosan yang spesifik yaitu –OH, -NH, -CH, -CN, and -CO.   Kata Kunci: Enzimatis, karakterisasi, kitosan.   Abstract. Chitosan can be isolated through the demineralization, deproteination and deacetylation. The aim of this experiment were to know the chitosan characterization from the shells of blood clams  which used papain enzyme on deproteination phase. In the deproteination phase was done enzyme volume and incubation time variation to get the lower total nitrogen which using Kjeldahl method. Chitosan characterization through the involve water, ash content, and functional group using FTIR spectroscopy. The characterization result of chitosan was showed the involve water is 1,16%, ash content is 1,25%, deacetylation degrees is 91,7% and have the  specific functional groups of chitosan is –OH, -NH, -CH, -CN, and -CO.   Key words: Enzymatically, characterization, chitosan

Statistical arbitrage in South African equity markets

The dissertation implements a model driven statistical arbitrage strategy that uses the principal components from Principal Component Analysis as factors in a multi-factor stock model, to isolate the idiosyncratic component of returns, which is then modelled as an Ornstein Uhlenbeck process. The idiosyncratic process (referred to as the residual process) is estimated in discrete-time by an auto-regressive process with one lag (or AR(1) process). Trading signals are generated based on the level of the residual process. This strategy is then evaluated over historical data for the South African equity market from 2001 to 2013 through backtesting. In addition the strategy is evaluated over data generated from Monte Carlo simulations as well as bootstrapped historical data. The results show that the strategy was able to significantly out-perform cash for most of the periods under consideration. The performance of the strategy over data that was generated from Monte Carlo simulations demonstrated that the strategy is not suitable for markets that are asymptotically efficient

Emerging and new pests under climate change in Limpopo Province, South Africa.

Doctor of Philosophy in Crop Science. University of KwaZulu-Natal, Pietermaritzburg 2018.Vegetable production is constrained by pests such as weeds, insects and diseases. The damage caused by pests and diseases can be highly exacerbated by climatic changes and variability. Poor agricultural practices play a role in increasing greenhouse gas emissions which contribute to climate change. Climatic factors such as increased temperature, increased carbon dioxide levels and erratic rainfall are responsible for influencing pest distributions, pest migration and increased pest population. Distribution and migration of pests can also result from globalization, trade and movement of people. Poor biosecurity and phytosanitary measures are also involved in bringing new pests in countries. This study was conducted in Limpopo Province in four municipalities of Vhembe District (Mutale, Musina, Makhado and Thulamela). Quantitative and qualitative techniques were used in data collection. Data was collected through questionnaire surveys, focus groups discussions and key informants. Farmers were randomly selected from a list provided by extension officers in each municipality. Three focus groups were conducted in each municipality consisting of seven women, seven men and a combined group of seven men and women. Statistical Package for Social Sciences (SPSS) was used to compare mean differences between different variables. Means and significant differences between means were declared at P ≤ 0.05. The aim of this study was to evaluate the presence of new and emerging pests in Limpopo Province. The major objectives of the study were to evaluate farmer’s perception on climate change and new and emerging pests, to determine the control measures used by farmers to manage vegetable insect pests, to evaluate the role of institutions on insect pest management, and to determine new and emerging pests in the district. Results of the study indicated that long dry spells, late rainfall and warmer winters were major indicators of climate change in Limpopo Province. Famers in all municipalities perceived aphids as major problematic insect pests to vegetables and were not significantly different from each other (P > 0.05). The highest percentage of aphid prevalence was found in Mutale municipality (82.1%) and the lowest was found in Thulamela municipality (66.7%). Tuta absoluta (South American tomato pinworm) and Spodoptera frugiperda were reported as new insect pests in Vhembe District. Tuta absoluta was only reported in Musina municipality. Spodoptera frugiperda was significantly higher in Makhado irrigated system (72%) and was significantly different from Musina municipality (8.3%) and Thulamela dryland system (19%). Bagrada hilaris (bagrada bug) and Acanthoplus discoidalis (armoured bush cricket) were observed as emerging pests in the district. Thulamela dryland system (73%) was significantly different from Thulamela irrigated system (33%) and Musina municipality (41%) in terms of Bagrada hilaris prevalence. Musina municipality (50%) was significantly different from the rest of the municipalities with respect to Acanthoplus discoidalis prevalence (P < 0.05). The lowest prevalence of amoured cricket was found in Mutale irrigated system (9.52%). All municipalities showed that they highly depended on chemical control for pest management. All municipalities except Makhado dryland system, mentioned that chemicals were effective for insect pest management. The percentage of farmers who agreed that chemicals were effective was significantly different from farmers who did not agree that chemicals were effective (P < 0.05). The overall study showed that climatic factors increased the prevalence of insect pests in Limpopo Province. High temperatures could have influenced the population and distribution of insect pests. New insect pests observed seemed to have quickly adapted to climatic factors in Limpopo Province and therefore, resulted to severe damage on host crops. The study also emphasized that chemical control was effective for insect pest management. However, farmers were over applying pesticides to kill insect pests. This resulted in high levels of pesticide resistance. Frequent application of pesticides can be harmful to the environment and to human health, and can also increase the level of pesticide residues on vegetables. More studies need to be conducted on the biology of new and emerging insect pests in Limpopo Province. Awareness on new and emerging insect pests must be raised to assist farmers in preparedness on how to manage insect pests. Farmers need to be trained more on chemical control measures and other control measures such as integrated pest management and biological control for pest management. The government should also train extension officers on climate change and insect pests, climate smart agriculture and effects of pesticides in order to deliver relevant advisory services to farmers

Microstructure and texture development in AISI430 ferritic stainless steel

AISI 430 ferritic stainless steel (FSS) is the most widely used FSS alloy due to good resistance to stress corrosion cracking. Owing to the chemical composition range, AISI 430 alloys undergo a partial phase transformation of ferrite to austenite when subjected to hot rolling temperatures. Consequently, the alloys consist of ferrite and austenite during processing. The presence of austenite and ferrite influences the microstructure evolution and texture development during hot rolling and subsequent annealing heat treatments. Two AISI 430 FSS heats of varying austenite volume fraction were used in this study. The two AISI 430 FSS heats were deformed using the first three passes of the Steckel mill hot rolling process. Post deformation heat treatments namely: continuous phase transformation and martensite tempering heat treatments were performed after three successive simulated Steckel mill passes. Microstructure analyses were performed using light microscopy and Electron Backscattered Diffraction (EBSD). The microstructure analyses were performed in order to determine microstructure evolution and texture development during hot deformation and post deformation heat treatments. The difference in austenite volume fraction in the respective heats A and B has profound influence on the possibilities for microstructure and texture evolution. For the higher austenite volume fraction heat A, the post-deformation path for austenite decomposition can lead to two very different textures in the prior austenite regions. During continuous diffusional transformation from austenite to ferrite the final texture is influenced by expected variant selection as well as growth selection during the prolonged isothermal heat treatment. The result is relatively strong {001} texture and comparably very weak γ-fiber texture. In the case of the martensite tempering process the γ-fiber texture that is inherited from the austenite to martensite diffusionless transformation is maintained in the prior austenite regions. The mode of post-deformation heat treatment does not significantly impact on texture development in heat B where the texture is dominated by recovery and growth in the primary ferrite phase

Environmental Contamination by Heavy Metals

The environment and its compartments have been severely polluted by heavy metals. This has compromised the ability of the environment to foster life and render its intrinsic values. Heavy metals are known to be naturally occurring compounds, but anthropogenic activities introduce them in large quantities in different environmental compartments. This leads to the environment’s ability to foster life being reduced as human, animal, and plant health become threatened. This occurs due to bioaccumulation in the food chains as a result of the nondegradable state of the heavy metals. Remediation of heavy metals requires special attention to protect soil quality, air quality, water quality, human health, animal health, and all spheres as a collection. Developed physical and chemical heavy metal remediation technologies are demanding costs which are not feasible, time-consuming, and release additional waste to the environment. This chapter summarises the problems related to heavy metal pollution and various remediation technologies. A case study in South Africa mines were also used

Effects of Leadership Style on Public Secondary Schools Teachers Performance In Tanzania: A Case Study of Kinondoni Municipality Dar es Salaam.

The study sought to explore the effects of leadership style on teacher’s performance at Kinondoni Municipal in Dar es Salaam. The study was guided by three objectives, namely; (i) to determine the effect of Autocratic leadership style on public secondary schools Teachers’ performance (ii) to determine the effect of Democratic leadership style on public secondary schools Teachers’ performance and (iii) to determine the effect of Laisse-Faire leadership style on public secondary schools Teachers’ performance. A quantitative research approach with descriptive survey design was used. A sample of 536 was drawn from 804 teachers as respondent. Simple random sampling was used to get respondents. Descriptive statistics and correlation analysis were used to analyse data. The study found that Autocratic leadership style was significantly negatively correlated with teachers’ performance; secondly it was found that Democratic leadership style was positively correlated to teacher’s performance and lastly the study found that Laissez faire leadership style was also positively and significantly related to teacher’s performance. Therefore the study recommends that the local government authorities where Kinondoni municipal council belong should make sure that all head teachers and head mistresses are trained on leadership skills whereby they will be effective in motivating, creating positive visions and involving other teachers in planning and executing school issues also among the three leadership styles studied on their effect on teachers performance, following the findings it is highly recommended that head teachers and head mistresses apart from using all leadership style. When teacher perceive the kind of leadership the headmaster or headmistress is applying have both positive and negative effect on the teacher’s performance. Keywords: Autocratic Leadership Style and Democratic Leadership Styl

Computational and experimental study for the desalination of petrochemical industrial effluents using direct contact membrane distillation

Abstract The petrochemical, mining and power industries have reacted to the recent South African water crisis by focussing on improved brine treatment for water and salt recovery with the aim of achieving zero liquid effluent discharge. The purpose of this novel study was to compare experimentally obtained results from the treatment of synthetic NaCl solutions and petrochemical industrial brines such as spent ion exchange regenerant brines and reverse osmosis (RO) brines to the classical well-known Knudsen diffusion, molecular diffusion and transition predictive models. The predictive models were numerically solved using a developed mathematical algorithm that was coded using MATLAB® software. The impact of experimentally varying the inlet feed temperature on process performance of the system is presented here and compared to simulated results. It was found that there was good agreement between the experimentally obtained results, for both the synthetic NaCl solution and the industrial brines. The mean average percentage error (MAPE) was found to be 7.9% for the synthetic NaCl solutions when compared to the Knudsen model. The Knudsen/molecular diffusion transition theoretical model best predicted the performance of the membrane for the industrial spent ion exchange regenerant brine with a mean absolute percentage error (MAPE) of 13.3%. The Knudsen model best predicted the performance of the membrane (MAPE of 10.5%) for the industrial RO brine. Overall, the models were able to successfully predict the water flux and can be used as potential process design tools