4. Electronic Theses and Dissertations (ETDs) - Faculties submissions
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Item 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.Item 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, JenniferBiometeorological 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.Item 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, LutshabaThis 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.Item Modelling for Rainwater Harvesting Structures Using Geospatial Techniques(University of the Witwatersrand, Johannesburg, 2024-10) Makaringe, Precious Nkhensani; Atif, IqraClimate 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.Item 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, JonesCurrency 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 makersItem 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, MatlalaPublic 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.Item 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 IkechukwuThis 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.Item The Impact of Digital Leadership on Digital Maturity: A South African Case Study(University of the Witwatersrand, Johannesburg, 2024) Jaffer, Aasma; Sethibe, TebogoIn the rapidly evolving landscape of digital transformation, the role of digital leadership in driving organizational maturity has become increasingly crucial. This study investigates the impact of digital leadership on digital maturity within the South African fintech sector, aiming to provide insights into the mechanisms through which leadership practices influence digital maturity at a factor level. This was broken down into two key areas: identifying the most critical indicators of digital maturity and investigating the impact of digital leadership on five factors of digital maturity based on the digital maturity model used. Drawing upon a conceptual framework rooted in the literature on digital leadership and digital maturity, the study utilises an established digital maturity instrument, the Unified Digital Maturity Model by Armstrong & Lee (2021). The research employed a quantitative approach, utilizing a sample of 150 employees from various fintech companies in South Africa. Data was collected through a structured survey instrument, and statistical analysis, including regression analysis, was conducted to examine the relationship between digital leadership behaviours and organizational digital maturity levels. The findings reveal significant positive correlations between digital leadership and all five factors of digital maturity studied, namely Customer Orientation & Engagement, Digital Product Innovation, Workforce Enablement & Performance, Core Processes Digitisation and New Value Streams & Business Models. The study identifies the top three most critical digital maturity constructs as Organisational Culture, Workforce Enablement & Performance, Customer Orientation and at indicator level, found eight critical variables. These results underscore the importance of cultivating digital leadership capabilities to foster high digital maturity and in turn, streamline digital transformation in the South African fintech context. The study concludes by highlighting the imperative for organizations to prioritize investments in digital leadership development as a strategic imperative for navigating the digital landscape effectively.Item Exploring temporal changes in the malting barley seed microbiome with meta-omics to understand nitrogen content effects(University of the Witwatersrand, Johannesburg, 2024-10) Tshisekedi, Kalonji Abondance; De Maayer, Pieter; Botes, AngelaBarley (Hordeum vulgare L.) is a critical cereal crop, particularly in beer production, where it plays a significant role in the economy, especially in South Africa. Despite its importance, the barley seed microbiome, which affects seed storage and quality, is not well understood. This research addresses two key questions: (1) how microbial composition and function evolve during storage and (2) how the inherent nitrogen content of the grain affects these dynamics. Using metagenomic and metaproteomic approaches, eight barley samples from the Kadie cultivar, stored for various durations (harvest, three, six, and nine months) with high and low nitrogen content, were analysed. Metagenomic sequencing revealed a predominance of bacterial sequences and minimal fungal presence, with storage time having a greater impact on microbial diversity than nitrogen content. However, specific bacterial genera such as Erwinia, Pantoea, Pseudomonas, and Stenotrophomonas showed nitrogen-dependent prevalence. Metagenome-assembled genomes (MAGs) were reconstructed, representing 26 bacterial genera, with minimal shared orthologues, highlighting taxonomic diversity. Functional analysis identified key metabolic pathways and carbohydrate-active enzymes (CAZymes) essential for microbial adaptation during storage. Metaproteomic analysis further showed the active expression of proteins related to nutrient transport and stress response, indicating functional changes over storage time. Overall, this research enhances the understanding of the barley seed microbiome, providing valuable insights into storage practices that could improve brewing quality and agricultural sustainability.Item Digital innovation and disruptive potential by FinTech companies in South Africa(University of the Witwatersrand, Johannesburg, 2024) Freund, Amelia; Omotoso, PelayoFinTech companies are seen bring innovation to the financial services industry that provide an enhanced customer experience and improves financial inclusion. A contradiction exists between academic and business literature around the potential impact of the FinTech revolution on the industry and banks as incumbents in the financial services industry. This paper aims to clarify this by assessing the degree of potential disruption that domestic new-entrant FinTech companies in the payments sub-sector have on incumbent banks in South Africa, so that both parties could make informed decisions that benefit the industry and its customers. This qualitative study examines the drivers of potential disruption and the decisions made by both FinTech new-entrants and banks to develop a synthesis for a likely future scenario relating to potential changes in dominance within the financial services industry. It further analyses the advantages and challenges of each party in the context of a potential partnership and examines management views to determine alignment with the drivers of disruption. This cross-sectional study employs document analysis to examine 42 new-entrant FinTech companies in the payments sub-sector and 5 banks, in addition to the thematic analysis of semi-structured interviews 15 semi- structured interviews conducted. It was found that domestic new-entrant FinTech companies are not likely to disrupt banks (to the point where FinTech companies become more dominant) in the payments sub-sector in South Africa due to the influence of banks in the industry and the proactive response from banks to potential disruptions. Banks should, however, take notice of developments and more seriously consider solutions in the cross-border remittance and blockchain spaces. Managers may have slight differences in their opinions, but overall, they are aligned with the factors driving disruption and the influence of FinTech companies on the financial services sector. This alignment enables them to make strategic decisions effectively without significant misconceptions. The study discovered a potential mutually beneficial link between FinTech companies and banks that indicate partnerships between them might enhance their services to customers and enhance their overall competitive standing in the market