3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item Catalytic production of biodiesel from waste cooking oil using calcium silicate(2018) Ntinugwa, Ndubuisi EbenezerThe production of biofuels has witnessed a renewed interest in light of finding alternatives to fossil fuels. One such important biofuel is biodiesel. Biodiesel made from waste vegetable oil (WVO) is particularly favorable due to the availability of waste as fuel source as opposed to oil derived from food plants. Biodiesel production can therefore loom as a large economic opportunity for South Africa, whose fuel is largely imported from crude-oil rich regions in the world. Despite the environmental benefit compared to the fossil fuel, bio-fuels production at industrial level is not currently financially attractive in comparison to the conventional diesel fuel prices. The market price of the produced biofuel depends on its feedstocks, which fluctuate significantly and affect the production cost. The purpose and aim of this research project is to combine and investigate the optimum conditions and the elementary reaction kinetics for the production of biodiesel from waste vegetable oil using a calcium silicate catalyst. The optimum conditions of interest are the methanol to oil ratio and the catalyst concentration. There are various methods available for the production of biodiesel. For this project, transesterification was discovered to be the most suitable, and was then used throughout during the experiment. Prior to the production of biodiesel the catalyst was prepared from a reaction containing calcium hydroxide and silica gel as the reactants. The catalyst was characterized using FTIR, BET, XRD and SEM determinations. The waste vegetable oil was also characterized in order to determine its free fatty acid (FFA) content, its density and its moisture content; which are all essential to the quality of biodiesel that could be produced. The biodiesel produced was confirmed using GCMS and its quality in terms of concentration was derived from its absorbance using an absorbance vs. concentration calibration curve. The results show that the optimum methanol to oil ratio at a constant temperature of 60 ℃, with a reaction time of 180 minutes is 3:1. The optimum catalyst concentration at the same reaction temperature and time was found to be 5%. The transesterification reaction in this project correlated to an irreversible first order kinetic model. The reaction kinetics depicted this catalyst as ineffective for transesterification since low reaction rates were observedItem Production of biogasoline from waste cooking oil as an environmentally friendly alternative liquid fuel(2017) Bridgiliah, Mampuru MadinogeEnergy is an important utility to human kind. Since the beginning of human civilization, human beings have become acquainted with travelling and transportation of goods. The use of conventional energy fuels for automobile engines is no longer sustainable due to finite crude oil reserves available in the world, of which many are facing the crisis of being depleted. The use of conventional fuels is a major contributor to environmental concerns such as global warming. Therefore there is an urgent need to explore alternative sources of fuel energy that are sustainable and environmentally friendly. The production of biofuels has been receiving increased academic and industrial attention as practical alternative fuel sources that can partially or completely replace conventional fuels. A study of the production of biogasoline from waste cooking oil as an alternative and re-usable source of liquid fuel was conducted in this project. This work focused on the variety of parameters that would deliver the optimum conversion and yield of biogasoline. The waste cooking oil was converted through catalytic hydrocracking in the presence of an acid activated Ni-Mo/Al2C>3 catalyst and constant hydrogen gas pressure of 0.5 kPa. A number of Ni-Mo/A^Oa catalysts were synthesized with varying Ni-loadings from 5-25 wt. % and calcination temperatures from 300 °C to 700 °C. The catalysts were characterised using ICP-OES, TGA, BET, SEM, FT-IR and Raman spectroscopy. Catalyst characterisation results revealed that the catalyst with 5 wt. % Ni possessed the greatest thermal strength, with the maximum BET surface area of 61.61 m /g and high dispersion of the active species in the catalyst. The optimal calcination temperature range for this catalyst was found from 500 °C to 600 °C. The effects of reaction temperature, reaction time, catalyst: oil ratio, catalyst calcination temperature and Ni-loading (wt. %) were investigated. The highest percentage of produced biogasoline was 59.50 wt. % at a reaction temperature of 250 °C, catalyst: oil ratio of 1:75, reaction time of 1 hr with a catalyst loaded with 5 wt. % Ni and calcinated at 300 °C. The use of stainless steel reactors that can handle higher reaction temperatures and pressure is recommended for future studies that will allow more severe cracking of the raw material into lighter hydrocarbons. The Ni-Mo/AhCT catalyst can also be modified with boron or fluorine to enhance its catalytic activity.Item Challenges in recycling used cooking oil to produce biodiesel in Polokwane(2016) Ramuedzisi, Humbelani ElsonIn response to the ever increasing problems associated with climate change, and greenhouse gas emissions, many countries in the world are developing and adopting climate change resilient policies that support green economy. Green economy sector in South Africa has not as yet received much expected attention as a key sector to address economic and environmental problems. The use and the production of renewable fuels, such as biodiesel are known to have significant economic and environmental benefits. However, progress in the production of biodiesel is hampered by limits imposed by government on the use of fresh vegetable extracted oils for production of biodiesel, mainly due to challenges on food security; and the impact this will have on food prices. In recent years recycling has become an important tool to address waste problems; pollution control; and socio-economic problems such as joblessness, poverty and social inequity. Used cooking oil has always been considered waste and an environmental burden. Therefore through technology advancement of recycling, wastes such as used cooking oil have become useful resources for biodiesel production. This research is about the challenges in recycling used cooking oil to produce biodiesel. The study recommended that in order to address challenges facing sustainability of our environment, and high unemployment rate; small recycling industries such as those operating in Polokwane will need government support such as biodiesel sector policies and regulations, to encourage investment in the biodiesel value chains in a way that will lead to the achievement of green economy goals.