4. Electronic Theses and Dissertations (ETDs) - Faculties submissions

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    Synthesis and characterization of onion-like carbons for adsorption of tartrazine dye in water
    (University of the Witwatersrand, Johannesburg, 2024-08) Cwayi, Herbert Qaqambile; Maubane-Nkadimeng, Manoko S.; Coville, Neil J.; Maboya, Winny K.
    Industrial effluent often can contain a significant amount of synthetic dyes. The discharge of wastewater containing dyes into water streams without proper treatment consequently enters the soil and disturbs the aquatic and terrestrial life. Several wastewater treatment technologies have been proposed that can efficiently reduce the amount of synthetic dyes from the environment, in particular azo dyes. Among all the existing technologies for wastewater treatment, physical adsorption is a popular technology because it is inexpensive, simple, and efficient. The aim of this study is to synthesize, modify, and characterize onion-like carbons (OLCs) derived from four different waste oils for the adsorption of tartrazine dye in water. The OLCs derived from different carbon precursors (waste household oil, restaurant waste oil, engine waste oil, and paraffin oil bath waste) were synthesized using a flame pyrolysis method. The synthesized materials were doped with nitrogen using a chemical vapor deposition technique using 10% ammonia gas as a source of nitrogen. The N-doped OLCs were attached with hydroxyl groups through oxidation reactions to improve their solubility and adsorption efficacy. According to the high-resolution transmission electron microscopy and scanning electron microscopy images, the OLCs from all four-carbon precursor were quasi-spherical, agglomerated, and presented a chain-like structures of multi-layers. The distance between the graphitic layers was found to be 0.32 nm. The average particle size of OLCs was calculated to be 40.2 ± 2.5 nm. Adsorption studies revealed that the initial dye concentration, contact time, and pH of the dye solutions influenced the adsorption capacity of the tetrazine. Nitrogen doping of OLCs increased its capacity to adsorb the tartrazine dye. The nitrogen doped OLCs from household waste oil (H-N-OLCs) and engine waste oil (E-N- OLCs) were used in equilibrium adsorption studies in this work. For a concentration of 20 mg/L of tartrazine dye, an adsorption capacity of 28.9 mg/g was achieved using the N- doped OLCs from household waste oil. The adsorption process follows the pseudo second- order kinetic model. The adsorption isotherm is best fitted to the Freundlich mathematical model. The results obtained show that, the source of oil did not have major effect on the physicochemical properties of OLCs and that incorporation of nitrogen onto carbon matrix enhanced the adsorption of the anionic tartrazine dye in aqueous solution.
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    Assessing the Validity of the Exclusion of Night-time Thermal Comfort in Tourism Climate Indices
    (University of the Witwatersrand, Johannesburg, 2024-09) Mnguni, Zandizoloyiso; Fitchett, Jennifer
    Biometeorological indices are instruments that can be used to streamline complex climatic information for economic and other decision-making. Indices hold inherent assumptions where the use of an index is only reliable and valuable if those assumptions are true. The Holiday Climate Index (HCI) is presented as the improved version of the TCI, with a key difference being the removal of night-time thermal comfort due to the assumption that air conditioning is ubiquitous throughout Europe. This study investigated the validity of this exclusion of night-time thermal comfort in tourism climate indices, particularly for the HCI using the six European cities for which the index was developed – Barcelona, Stockholm, London, Istanbul, Paris and Rome. The assumption of ubiquitous air conditioning was investigated using Booking.com accommodation listings, the night-time economy and prevalence of night-time activities outside of each accommodation establishment, and whether tourists experienced adverse thermal comfort during the night through posted reviews. Without the air conditioning filter applied, the proportion of listings categorized as offering air conditioning ranged from 28.8% for Stockholm to 98.9% for Rome. With the filter applied, the proportions ranged from 96.4% for Stockholm and 99.0% for Paris. A total of 24,252 TripAdvisor reviews were also examined for both accommodation establishments and night-time tourist activities. The reviews were manually examined for the mention of weather, climate, night-time temperature and air conditioning. The findings of this study exhibit a range of night-time activities, many of which are outdoors, where tourists did comment on night-time thermal comfort. The research disproves the claim of the original authors, and it was found that air conditioning is not ubiquitous. Therefore, the assumption that the HCI is based on is problematic, and the index should be used with caution. Moreover, a similar approach in index validity testing should be performed prior to future studies seeking to apply indices.
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    Mechanisms that enable the use of M&E information in decision-making to improve programme outcomes in the Centre for the Study of Violence and Reconciliation
    (University of the Witwatersrand, Johannesburg, 2024) Fanelwa, Lutshaba
    This study aims to show how employees employed by the Centre for Study of Violence and Reconciliation (CSVR) for a minimum of six months use M&E data to guide decision making choices and improve programme outcomes. To explore and appreciate the mechanisms and processes of decision-making using data from individuals collecting data and those making decisions in the organization, a research design used a case study through a qualitative method approach. One of the issues facing the NGO sector is the lack of documentation about the use of monitoring and evaluation data in decision-making procedures (Bornstein, 2006). Comprehending how gathered and processed data is used and how it improves programme outcomes is challenging because of this deficiency. The planned study will examine the various ways the organization uses data to make choices, as it is currently unclear if CSVR has the same conceptualization issues with data use and practice. The investigation results verified that the organization is faced with the same issue of inadequate documentation of its processes for monitoring and evaluation. This is made clear by the M&E framework, which provides insufficient information on database administration, information consumption, and routine data management activities. Using data and making decisions are related. The organization's decision-making process is not well understood; some people think decisions are made collaboratively by the team at weekly meetings, while others think project managers are in charge of making decisions. Decision-making and standardization in the application of knowledge are impossible without a functioning M&E system. The organizational structure makes it difficult to adopt an M&E system completely since it affects other programme support and where the unit fits in the organogram. M&E only provides support for one programme.
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    Modelling for Rainwater Harvesting Structures Using Geospatial Techniques
    (University of the Witwatersrand, Johannesburg, 2024-10) Makaringe, Precious Nkhensani; Atif, Iqra
    Climate change poses a significant threat, leading to droughts, floods, and hindering sustainable development. Water scarcity is a growing concern, particularly in developing countries like South Africa, where limited freshwater resources are further strained by climate variability. This research explores the potential of rainwater harvesting (RWH) as a strategy to address water scarcity in such regions. This study aims to model potential rainwater harvesting sites in Lynwood Park, Pretoria, South Africa, utilising geospatial techniques. Object-Based Image Classification (OBIC) was employed to extract building footprints from high-resolution satellite imagery. Microsoft and Google building footprints were utilised to determine the suitable automated building footprints for Lynnwood Park. ArcGIS Pro software served as the primary platform for spatial data analysis and mapping potential RWH sites. Data integration included high-resolution satellite imagery, a Digital Elevation Model (DEM), building footprints, and rainfall data. Additionally, questionnaires were distributed to estimate population and water demand within the study area. The research demonstrates the efficacy of geospatial tools in identifying suitable locations for RWH systems. Indicating that steeper slopes in the southern region of Lynnwood Park have limited collection from large rooftops, while the flatter north offered greater potential. Rainfall graphs and PRWH results suggest that over half of Lynwood Park's annual water demand could be met through rooftop rainwater collection. However, factors such as system losses due to evaporation, inefficiencies in collection and storage, and variability in rooftop sizes across different buildings would need to be incorporated into more detailed models, as well as water quality analysis for rooftop harvested water in future studies. This study highlights the potential of RWH as a viable water security strategy in water-scarce regions. The findings contribute to the development of geospatial approaches for RWH implementation, promoting water security and sustainability in a changing climate.
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    Currency Volatilities of BRICS Countries: The Impact of Commodity Prices, Interest Rates and Geopolitical Risks
    (University of the Witwatersrand, Johannesburg, 2024) Luo, Heng; Odei-Mensah, Jones
    Currency volatility in emerging markets is an interesting topic for managers, investors, and regulators. This study investigated the currency volatility of the five BRICS nations, examined the risk sources of the BRICS currencies and observed the connectedness of their currency risks, in the context of the COVID-19 pandemic, Russia-Ukraine war and current interest rate hikes, using data spanning between September 2011 and September 2023. The ARDL model was the main econometrics approach applied for identifying the long run and short run currency volatility determinants. In addition, Quantile Regression was adopted to observe the currency markets’ tail behaviours. The research has three major findings. Firstly, the research confirmed that interest risk, commodity risks, geopolitical risk, and economic policy uncertainty are the risk sources of BRICS nations’ currencies, especially when volatilities are at high levels. Additionally, the research provided support for spillover of the commodity market, the USA’s geopolitical risks and economic policy risks to the BRICS’ currency markets, and the volatility spillover across BRICS currency markets. Finally, the study revealed the shock evolution trend of Chinese RMB, with accelerating impacts of US geopolitical risk, US and home economic policy risk, and oil price exposure on RMB’s volatility. Overall, the heterogeneity of BRICS nations’ currency markets responding to external shocks, and the asymmetry of the connectedness of BRICS currency markets, were important implications of the research. The findings are crucial for investors and policy makers
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    Factors contributing to transgressions in the procurement practices of state-owned entities (SOES): Eskom and Transnet
    (University of the Witwatersrand, Johannesburg, 2024) Moloto, Bonolo; Setlhalogile, Matlala
    Public procurement is a vital process for governments and state-owned enterprises (SOEs) to procure essential goods and services. However, state capture and unethical practices have plagued it. The State Capture Commission Report highlighted issues such as poor governance, unethical conduct, and insufficient internal control systems. This has led to financial and operational challenges for SOEs, which heavily rely on state guarantees and bailouts. In South Africa, the government spends around R1 trillion annually on procurement, which represent 12% of the country’s gross domestic product (GDP) (National Research Foundation, n.d.). The Auditor General (AG) report for the 2020/21 financial year reported that most SOEs had high balances of irregular expenditures. Transnet had the highest irregular expenditure, totalling R14.1 billion, followed by Eskom with R11.6 billion (Maeko, 2021). This study aimed to identify the underlying governance factors contributing to transgressions in SOE procurement practices and to provide remedial actions to prevent recurrence. Agency Theory was used to examine the identified issues, and a comprehensive literature review was conducted to investigate the underlying factors. The study found that failure to address these governance issues could lead to qualified audit opinions, issues of going concerns for SOEs as well as impact investments and public confidence. The study also revealed that the slow implementation of consequence management could foster a culture of noncompliance and accountability. The current South African public procurement system ca is characterised by political interference and cadre deployment, which undermines transparency, accountability, and good governance. Political appointments and cadre deployment in critical positions encourage wasteful spending, undermine governance, and promote dictatorship. Politicised boards and management in SOEs has led to an increasing prevalence of corruption. The AG, Standing Committee of Public Accounts (SCOPA), National Treasury (NT), Department of Public Enterprises (DPE), and the respective SOEs’ boards have been unable to conduct their oversight functions effectively due to their unwillingness to do the right thing and failure to establish robust preventative controls. The state's approach to board nomination lacks transparency, operates in an ad hoc manner, and is excessively politicised. iii Remedial actions to address these issues require a dedicated commitment from top leadership, fast implementation of corrective measures, and periodic monitoring and evaluation processes. Limiting political interference in the administration of remedial actions can enhance the effectiveness, fairness, and integrity of the anti-corruption process.
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    Microwave-assisted synthesis of palladium-based ferroalloy electrocatalysts for application in alkaline direct alcohol fuel cells
    (University of the Witwatersrand, Johannesburg, 2024-11) Ramashala, Kanyane Nonhlanhla Eugenia; Billing, Caren; Modibedi, R. Mmalewane; Ozoemena, Kenneth Ikechukwu
    This research work describes the study of Pd-based ferro-electrocatalysts for application towards direct ethanol fuel cells (DEFCs), direct ethylene glycol fuel cells (DEGFCs), direct glycerol fuel cells (DGFCs) and oxygen reduction reaction (ORR) operated in a basic environment. The initial part of the research was to explore the Pd-based monometallic and bimetallic (Pd/C and PdFe/C) by utilising varied methods such as the conventional sodium borohydride (NaBH4) and microwave-assisted technique (MW) towards the oxidation of glycerol (gly), intending to choose the best method viable for these catalysts. This study revealed that MW techniques tuned the physicochemical properties of Pd/C and PdFe/C by augmenting their crystallinity and defect. These led to improved electrocatalytic activities towards glycerol oxidation reaction (GOR) over NaBH4 technique. MW process as a powerful tool was further used in the entire study to synthesise bimetallic and trimetallic electrocatalysts in ethanol (EtOH), ethylene glycol (EG) and glycerol (Gly) oxidation reaction in an alkaline environment. The synthesised bimetallic catalysts studied in this research work were (PdFe/C, PdCo/C, and PdMn/C) at varied ratios of Pd: M (Pd2M/C (2:1) and PdM/C (1:1)). Amongst them all, Pd2Fe/C and PdFe/C were observed to be the most favourable catalysts towards all the alcohols, with the excellent specific activity of about, for EtOH (11.59 and 4.15 mA cm-2), EG (9.82 and 5.51 mA cm-2) and Gly (8.94 and 4.73 mA cm-2), respectively. The satisfactory performance exhibited by the PdFe/C electrocatalyst prompted the exploration of the second 3d transition metal (PdFeMn/C and PdFeCo/C), intending to investigate the synergistic behaviour between the non-noble metals and Pd. The XRD confirmed that these electrocatalysts are in a crystalline nature with a decrease in d spacing (from 0.2247 nm, PdFe/C to 0.2236 nm (PdFeMn/C)) after the insertion of Mn into PdFe/C. This was supported by the TEM images obtained for the PdFeMn/C catalyst with a particle size of sub 10 nm. The comparison studies towards EtOH, EG and Gly were investigated for all the electrocatalysts and there was a remarkable observation, which is dissimilar from the theoretical studies (DFT). Density Functional Theory (DFT) revealed that PdFeCo performed better in terms of Gibbs free energy, binding energy, and energy band gap than PdFeMn; however, the experimental studies favoring the performance of PdFeMn. The PdFeMn/C delivered the best electrochemical activities, including a superior electrochemical active surface area (ECSA), larger current densities and mass activity response, and less susceptibility to poisoning and high conductivity as compared to PdFe/C and PdFeCo/C electrocatalysts. Furthermore, the PdFeMn/C electrocatalyst exhibited remarkable electrochemical properties during the ORR (basic medium). Ultimately, the best two anode electrocatalysts (PdFe/C & PdFeMn/C) were explored and tested for the proof-of-concept in the two-electrode configuration with the micro-3D printed cell. The PdFeMn/C delivered improved µ-ethylene glycol fuel cell, µ-glycerol fuel cell, and µ-ethanol fuel cell activities with respective to high voltage and power density of 33.27 mW cm-2, 11.00 mW cm-2 and 45,80 mW cm-2 respectively, operated at 100 mV / s. These electrocatalysts have demonstrated promising results in advancing ADAFCs.
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    The implications of mandible morphology and dental structure on the feeding ecology and predatory behaviour in Hyaenidae (hyenas) using geometric morphometric analyses
    (University of the Witwatersrand, Johannesburg, 2024-03) Naidoo, Riyanta; Iqbal, Safiyyah
    Hyenas are often overlooked as being successful predators due to their scavenging behaviour. However, their morphological adaptations allow them to succeed in bone-cracking behaviour, an act that most carnivores are unable to achieve. Craniodental morphology influences carnivore performance, therefore understanding the functional morphology of carnivore mandibles would allow for the justification of Hyaenidae behaviour. This study investigates the morphological differences between the Hyaenidae mandible and large carnivore mandibles in Africa, as well as the differences in mandible morphology within the Hyaenidae family. This study uses a two-dimensional landmark-based geometric morphometric methodology to analyse morphological features on the carnivore mandibles and dentition to determine the morphological clusters linking the carnivore species, determine how the mandible morphology accommodates biomechanical needs, and to determine the implications that mandible morphology and dentition has on feeding ecology. The results of this study indicated that the sizes (PC1) of the carnivore mandibles were clustered according to their respective families (i.e. Hyaenidae, Canidae, and Felidae), however the shape (PC2) of the mandibles differed according to diet. The mandible morphology of the hypercarnivorous Hyaenidae displayed evident adaptations to osteophagy behaviour, including a thickened corpus, a large masseteric fossa, an anteriorly-displaced coronoid, and robust and blunt-like canines. The Proteles cristata, however, displayed mandibular adaptations to a hypocarnivorous diet. Ultimately, it was found that an increased resistance to bending forces and an increased area for muscle attachment on the mandible, directly relates to an increase in the Hyaenidae bite force, improving their feeding and hunting success.
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    Exploring the role of social media influencers and brand ambassadors in influencing purchase intention
    (University of the Witwatersrand, Johannesburg, 2024) Da Fonseca, Helen; Saini , Yvonne
    This study investigates the comparative influence of social media influencers and celebrity brand ambassadors on purchase intention within the South African cosmetics industry, specifically targeting millennial and Generation Z consumers. Grounded in the Source Credibility Model, the research examines how credibility, trustworthiness, and expertise shape consumer decision-making. Social Media Influencer-Driven Purchase Intention (SIPI) and Brand Ambassador-Driven Purchase Intention (BAPI) were introduced as higher-order constructs to evaluate and compare which type of endorser has a stronger influence on overall purchase intention. A Structural Equation Modeling (SEM) methodology was used to analyse survey data collected from 130 respondents. The findings indicate that both Social Media Influencer-Driven Purchase Intention (SIPI) and Brand Ambassador-Driven Purchase Intention (BAPI) influence consumer purchase intention, with celebrity brand ambassadors exerting a more substantial effect due to their higher perceived credibility and expertise. Celebrity brand ambassadors were shown to play a pivotal role in enhancing consumer trust and confidence, making them more effective in driving purchase behaviour compared to social media influencers. These insights offer strategic guidance for marketers and brands looking to refine their influencer marketing strategies to better resonate with the evolving preferences of millennial and Generation Z consumers in the South African market.
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    The evolution of consolidation accounting: an application of chaos and memetic evolution theory
    (University of the Witwatersrand, Johannesburg, 2024) Van Zijl, Wayne; Maroun, Warren
    Many researchers have explored the evolution of accounting either as a technical and quasi- scientific discipline or as a social construct that both influences and is influenced by history. Some researchers have considered the role played by agency costs, economic pressures, regulation and the complexity of modern business. Other researchers have focused on political lobbying, the socialisation of accountants and the agency they have when applying accounting prescriptions as key evolution factors. The impact of power struggles and acts of resistance have also received much attention. This thesis builds on these earlier works by proposing a novel framework of accounting evolution inspired by two non-accounting theories: Darwin’s theory of evolution by natural selection and chaos theory. Using the case of consolidation accounting, 30 detailed interviews with local and international financial reporting experts illustrate how accounting theory and practice evolve at the macro- and micro-level. In doing so, the thesis helps to reflect how different perspectives highlighted by the prior literature can function concurrently under the proposed framework. The application of chaos theory suggests that consolidation accounting’s macro evolution is characterised by five observations. Firstly, consolidation accounting’s evolution is intertwined with and influenced by other systems, including business practice, taxation regulations, social norms and economic pressures. Secondly, accounting’s future state is highly dependent on its current state. This creates a path-dependency where its trajectory up to a specific point constrains its trajectory after that point. Thirdly, consolidation accounting remains relatively unchanged (stable) until it is disturbed. The presence of feedback loops may amplify or dampen disturbances leading to the possibility of disproportional change. Fourthly, consolidation accounting’s evolution indicates the presence of fractals, where the evolutionary pattern observed at one level resembles that of another. Fifthly, the accounting “rules-of-thumb” that develop over time may more accurately be described as strange attractors that pull accountants towards specific techniques, concepts and disclosures. In doing so, they create a sense or order because they limit the countless possibilities about how transactions and events might be treated. The application of Darwin’s theory of natural selection to non-biological systems is called memetic evolution. Considering memetic evolution of consolidation accounting at the micro-level reflects five core observations. Firstly, memetic evolution explains why accounting’s future state is Page 6 of 217 dependent on its current state. No “new” consolidation accounting technique, concept or disclosure (meme) is truly original but is a modification or recombination of one or more existing memes. Accordingly, consolidation accounting’s future state is dependent on its current state. Secondly, memetics shed additional light on how and what constitute disturbances under chaos theory. Disturbances can arise from changes to related systems, inaccurate inheritance processes, through the active modification of existing memes or the degradation of memes in accountants’ memory. Thirdly, memetic evolution enhances our understanding of feedback loops identified by chaos theory and why radical changes are often rejected in favour of marginal change. Fourthly, memetic evolution exhibits that consolidation accounting’s evolution is about the selfish replication of accounting memes. Consequently, researchers should not assume that currently accepted theory and practice represents the “best” or most “desirable” accounting prescriptions. Supporting chaos theory’s path-dependency, memes use different strategies to “win” the accounting meme selection game and become more prolific. Consequently, the criticism that accounting incentives short-term profit seeking behaviour may not represent a shortcoming of the accounting community but rather the power of evolution by natural selection. Finally, related systems co-evolve creating a complex and chaotic dynamic evolutionary environment. While the focus of the thesis is consolidation accounting, the findings are broadly applicable to accounting evolution in general. For example, the findings suggest that the accounting standard setters may serve the profession better by developing short- to medium-term accounting standards as opposed to striving to set more permanent standards. The findings form the foundation of a new research agenda into the chaotic and memetic evolution of accounting. However, there are limitations to the current study. Only purposive sampling 30 interviews were conducted to ensure participants had the qualifications and experience to provide meaningful insights, introducing an inherent bias potential.