3. Electronic Theses and Dissertations (ETDs) - All submissions
Permanent URI for this communityhttps://wiredspace.wits.ac.za/handle/10539/45
Browse
2 results
Search Results
Item The effect of temperature and headspace on the determination of ethanol in post-mortem blood specimens: A South African perspective(2019) Southon, BiancaThe Forensic Chemistry Laboratories in South Africa have, between the year 2014 and 2017, endured a lot of media scrutiny surrounding a backlog of specimens for blood alcohol and toxicology analyses and the poor environmental and storage conditions in which these specimens are kept. Many studies have been performed on the stability of alcohol in blood, since environments are not standard, to gain a better understanding on whether the backlog issues significantly impact on the integrity of the blood-alcohol concentration (BAC) results by evaluation of conditions, especially variables such as temperature and headspace. The aim of this study was therefore, to assess the stability of ethanol concentrations in post-mortem blood specimens by evaluating temperature (room and refrigerator) and headspace (4mL and 8mL) variables at 3 months and 6 months respectively. Blood from 119 decedents was collected, analysed and subjected to the varied volumes and storage conditions. Blood alcohol was determined and quantified using a G1888 Headspace Auto sampler (Agilent Technologies®) coupled to a 6890N Agilent® Gas Chromatography instrument utilising a Flame Ionization Detector on an Agilent HP-Innowax® column. A general decrease in alcohol concentration was observed over a storage period of 6 months regardless of the storage temperature, whilst headspace was found to have no significant effect on the BAC results. It is, therefore, important that Forensic Pathologists, investigators and scientists are aware of factors such as temperature and headspace and consider them when interpreting blood alcohol results from a post-mortem environment.Item Biogasoline production from waste cooking oil using nano-cobalt molybdenum catalyst(2016) Mabika, KudzaiThe world is gradually shifting to renewable clean energy and away from fossil fuels which are considered to have a finite reserve and have negative impact on the environment. Many alternatives have been developed including biofuels. Of the biofuel family, not all products are produced at the same level given the differences in technological advancements. Commonly produced biofuels which are commercialised are bioethanol and biodiesel. Given that a large number of vehicles operate using gasoline, there is a need to develop biogasoline specific processes to produce biogasoline. Bioethanol is used as a blending agent and has a drawback of engine corrosion. Biogasoline can be used for blending or to substitute gasoline in existing motors. The main objective of the project was to produce biogasoline from waste cooking oil using nano-particle catalyst for better performance. A Co-Mo/Al2O3 catalyst was synthesized and tested in two processes namely thermal cracking and hydrocracking. The waste cooking oil used in this study was pre-treated to remove salts and excess water prior to cracking process. Various analytical techniques were then used to characterize the catalyst, waste cooking oil and the products. Waste cooking oil was successfully pre-treated for salt removal with salt dropping from 13.18% to 4.37%. Effect of catalyst performance on thermal cracking proved to be minimal with temperature being the major factor in cracking. The catalyst performed better under hydrocracking with effects of catalyst calcination temperature and catalyst/oil ratio being more apparent as opposed to thermal cracking. Highest percentage biogasoline achieved under thermal cracking was 81.6% at a reaction temperature of 600°C. The highest percentage biogasoline achieved under hydrocracking was 75.7% at a reaction temperature of 210°C, using calcined catalyst at 700°C, catalyst/oil mass ratio of 1/75 and reaction time of 1hr. The biogasoline produced had low sulphur content. The highest sulphur containing product for hydrocracking was 7.4% and that for thermal cracking was 1.3%. It is recommended that the hydrocracking and thermal cracking methods be used for biogasoline production and that further research be done on the optimization of the biogasoline production process and synthesis of nano Co-Mo catalyst.