Theses and Dissertations

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    The dissolution of limestone, coal fly ash and bottom ash in wet flue gas desulphurization
    (2015-03) Koech, Lawrence; Rutto, H. L.
    Strict environmental regulation on flue gas emission has led to the implementation of FGD technologies in power stations. Wet FGD technology is commonly used because it has high SO2 removal efficiency, high sorbent utilization and due to availability of the sorbent (limestone) used. SO2 is removed by passing flue gas through the absorber where it reacts with the slurry containing calcium ions which is obtained by dissolution. This study presents the findings of the dissolution of a calcium-based material (limestone) for wet FGD process. This was done using a pH stat apparatus and adipic acid as acid titrant. Adipic acid was used because of its buffering effect in wet FGD process. The conditions used for this study are similar to what is encountered in a wet FGD process. The extent of dissolution was determined by analyzing the amount of calcium ions in solution at different dissolution periods. The dissolution kinetics were correlated to the shrinking core model and it was found out that chemical reaction at the surface of the particle is the rate controlling step. This study also investigated the dissolution of coal fly ash and bottom ash. Their dissolution kinetics showed that the diffusion through the product layer was the rate controlling step due to an ash layer formed around the particle. The formation of ash layer was attributed to pozzolanic reaction products which is calcium-alumino-silicate (anorthite) compounds were formed after dissolution. The effect of fly ash on the dissolution of rate of limestone was also studied using response surface methodology. Limestone reactivity was found to increase with increase in the amount of fly ash added and the pH was found to be strong function of the rate constant compared to other dissolution variables. The presence of silica and alumina in fly ash led to a significant increase in the specific surface area due to hydration products formed after dissolution.
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    Synthesis and characterization of silver and silver selenide nanoparticles and their incorporation into polymer fibres using electrospinning technique
    (2015-03) More, Dikeledi Selinah; Moloto, M. J.; Moloto, N.
    Here, we report the synthesis and characterization of silver (Ag) and silver selenide (Ag2Se) nanoparticles using the metal-organic route method. This method involves the reduction of selenium powder and silver nitrate in the presence of trioctylphosphine as a solvent. Tri-n-octylphosphine oxide (TOPO) and hexadecylamine (HDA) were used in the study as capping molecules. The optical properties of the as-prepared nanoparticles were studied using UV-Visible and photoluminescence spectroscopy (PL). Transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) were used to study the structural properties. The effect of capping molecules and temperature were investigated on the growth of the nanoparticles. The prepared nanoparticles seem to depend on the reaction temperature were the increase in temperature led to an increase in particle sizes. The growth of the as-prepared TOPO-capped Ag2Se nanoparticles was influenced by temperature, this was evident when the temperature was increased, the nanoparticles evolved from sphere to hexagonal shape. TOPO-capped nanoparticles showed the tendency of agglomeration with increase in temperature compared to HDA-capped nanoparticles. The X-ray diffraction results showed peaks which were identified as due to α-Ag2Se body centered cubic compound for both TOPO/HDA-capped Ag2Se nanoparticles. Some evidence of impurities were observed in the XRD analysis and indexed to metallic silver. HDA-capped Ag nanoparticles were found to be affected by temperature variation. The prepared nanoparticles were characterized with UV-Vis spectroscopy and transmission electron microscopy. XRD analysis was not performed due to small yield obtained. The absorption spectra of HDA-capped Ag nanoparticles at different temperatures show a surface Plasmon resonance (SPR) band in the regions 418 - 428 nm. Uniform spherical shapes were obtained for both 130 and 190 °C and fewer particles were obtained at 160 °C. The synthesis of TOPO–capped Ag nanoparticles was unsuccessful since none of the particles were isolated from the solution due to its lower capping ability or it may be that TOPO is binding too strongly to Ag. The polymer nanofibres were electrospun using electrospinning technique. Parameters such as concentration and voltage were investigated. These parameters significantly affect the formation of fibre morphology. PVP and PMMA polymers were used for this study. The electrospun composite fibres were characterized using UV-Visible spectroscopy, scanning electron microscopy (SEM), Thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and Fourier transformer infrared (FTIR) spectroscopy. The SEM results show that increasing the polymer concentration resulted in increased fibre diameters. Hence increasing the voltage decreases the fibre diameters. Ag2Se nanoparticles were incorporated into PVP and PMMA and electrospun using electrospinning to produce composite fibres. Their addition into PVP polymer fibres improved the fibre’s uniformity and further decreased their diameters. The SEM of composite fibres for PMMA is not shown. The absorption bands for PVP composites fibres show a blue shift from the pure Ag2Se nanoparticles, whereas the one for PMMA show a red shift from the pure Ag2Se nanoparticles. Both the composite fibres for PVP and PMMA show a blue shift from the bulk of Ag2Se. The XRD analysis of the composite fibres shows no significant effect upon addition of Ag2Se nanoparticles on the amorphous peak of the PVP polymer, whereas on the PMMA, it shows peaks which were due to the face centered cubic phase of Ag. The FTIR spectra of the composite fibres and pure polymers (PVP and PMMA) gave almost identical features. TGA curves show no significant effect on the thermal properties of the PVP polymer and its composites, however, on the PMMA composite fibres it show an increase in the thermal stability of the polymers upon addition of Ag2Se nanoparticles. The study was based on silver nanoparicles and its antibacterial activities. One of the synthetic challenges for silver nanoparticles is their solubility and yield. Selenide was introduced in the study to improve such shortcomings of silver nanoparticles and also for possible improved properties, chemical stability and increased activity against bacteria. The selenide group on the metal also provides stronger chemical interaction between the nanoparticles and the polymer. Therefore, the intension was to use these nanoparticles into polymer fibres for potential use in wound dressing.
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    Job seekers' perceptions about the PNet website as an E-recruitment tool within South Africa
    (2013-07) Lesuthu, Kali; Grobler, B. R.; Joubert, P. A.
    E-recruitment is one of the e-commerce applications that has enjoyed a multiple growth since its introduction in the early 1990s. There have been many variations regarding sophistication, types and success; as a result, this has posed a number of challenges to all stakeholders in these technologies. Thus, specific stakeholders may find specific applications suitable for their needs or within their reach to utilise. Companies can use these applications by implementing their own e-recruitment systems or by buying e-recruitment services provided by the third party, or a combination of both, depending on their objectives. The current study is focused on e-recruitment service providers who use general-purpose job boards that are fairly advanced in sophistication, such as the PNet recruitment website. These e-recruitment service providers are mostly recognised as online firms that manage their operations through their websites. However, behind these websites the physical ordinary businesses utilise the Internet as a means to perform their operations. Like other businesses, these e-recruitment service providers constantly face rapid shifts in technology, which places a considerable amount of pressure on them, as they persistently have to seek ways to stay ahead of their competitors. The competitiveness of every business lies in their knowledge of the market in which it operates in, as well the extent to which it is able to meet the needs of its customers. This study extends market knowledge and satisfaction of customers’ needs in the context of e-recruitment. It views the job seekers as the major customers for sustainability and competitiveness for e-recruiting companies or firms. The study was conducted using a survey method, sampling with n = 717 job seekers who use the PNet website to search for jobs. The primary data was obtained from the sample by means of a 6-point Likert questionnaire ranging from 1=strongly disagree to 6=strongly agree, measuring factors that influence the perceptions of job seekers regarding their use of the website. The questionnaire was administered via the Internet using the Sogo-Survey online tool. The main objective of the study was to evaluate job seekers’ perceptions about the PNet website as an e-recruitment tool, as well as to discover which factors are the best predictors of the continued use of the PNet website. The job seekers’ perceptions about the PNet website, as an e-recruitment tool in South Africa, were founded on the nine theoretical factors used in the questionnaire. From these factors, statistically significant differences in the factor means were present within the two independent groups, namely qualifications and gender. Using the standardised Beta value (β) the findings revealed that the attitude towards the website (.285) was the most important predictor, followed by information timeliness (.231), then attraction to the website (.182), usefulness of the website (.180) ease of use of the website (.170) and quality of website (.167). Findings and recommendations of this study are of importance to recruitment service providers and employers as it provides crucial information regarding their markets and how to improve the profitability of their businesses.
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    Supply chain relationships as predictors of supply chain performance in South African SMEs
    (2015-05) Pfanelo, Nematatani; Chinomona, Richard; Mathu, Ken
    The growth and development of SCM is attributed to number of factors such as partnership, collaboration, integration and relationship commitment. Despite increasing awareness of the importance of joint venture to organisations, research on the supply chain relationships (supply chain partnership, collaboration, integration and relationship commitment) and performance have received little attention. Therefore, using a data set of 271 individuals from the small and medium enterprise (SMEs) sector in South Africa, this study examines the influence of supply chain partnerships on collaboration, collaboration on integration, integration on relationship commitment and relationship commitment on performance. Structural equation modeling (SEM) method was used to analyses the data collected whereby individuals agrees with that supply chain relationships increase performance in the work environment. The study has developed a supply chain management (SCM)-based performance measurement system (PMS) for the case of SMEs. Such a framework may help SMEs managers to establish their own supply chain functions and strategically plan improvements for weak areas. In addition, it may remain helpful for benchmarking current practices with industry norms requirements. Quite often, companies dealing with a large number of performance measures derived and expanded based on the suggestions from employees, consultants and past experiences (history) forget to realise that supply chain performance measurement can be better addressed when they joint venture.
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    Photocatalytic treatment of industrial wastewater containing citric acid and toxic heavy metals
    (2014-12) Baloyi, Siwela Jeffrey; Aoyi, Ochieng
    The co-existence of organic acids and toxic heavy metals in natural water creates harmful effects on human, plants and animals. Therefore, it is necessary to treat organic acids and toxic heavy metal contaminated wastewater prior to its discharge to the environment. The aim of this study was to apply co-treatment of industrial wastewater containing citric acid and toxic heavy metals in single and binary systems using photocatalysis process. The hydrothermal method was used to synthesise dandelion-like TiO2 structures. Modifications of the dandelion-like TiO2 by deposition of gold nanoparticles and immobilisation on calcium alginate were done using deposition precipitation and one-step encapsulation methods, respectively. Dandelion-like TiO2 and dandelion-like TiO2 immobilised on calcium alginate (Alg/TiO2) were used as photocatalysts for Cr(VI), Hg(II) and citric acid removal from water. The results showed that the production of dandelion-like TiO2 structures strongly depends on the reaction time and synthesis temperature as key process parameters. The characterisation of the dandelion-like TiO2 by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and Brunauer-Emmett-Teller (BET) revealed the crystal structure, morphology, chemical composition and surface area. It was found that the efficiency of photocatalytic process depends on the type of pollutants, initial pH of the solution, photocatalyst dosage, contact time, substrate initial concentration, UV wavelength and light intensity. The reduction efficiency of Cr(VI) ion and citric acid increased with decreasing the initial pH values and initial concentration. On the other hand, Hg(II) reduction efficiency increased with increasing the initial pH values and initial concentration. In a binary system, the reduction of Cr(VI) and Hg(II) was found to be faster than in the single and ternary systems. The relationship of the chemical reaction rate of Cr(VI), Hg(II) and citric acid were expressed by the pseudo-first-order kinetic equation. Addition of ferric ions to Cr(VI)-citric acid complex and Hg(II)-citric acid complex enhanced the reduction of Cr(VI) and Hg(II), a complete reduction was accomplished within 30 and 60 minutes (min) of irradiation time, respectively. The reduction efficiency of both Cr(VI) and Hg(II) in the presence of citric acid in a solution was still significant after four times of Alg/TiO2 reuse. These results indicated that the UV/TiO2 photocatalysis process can be considered as a suitable method to reach a complete reduction of Cr(VI) and Hg(II) in the presence of citric acid in a solution.
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    Anaerobic co-digestion of abattoir and textile industry wastewater in a UASB reactor
    (2015-04) Ondari, James Maati; Ndege, Maurice S.; Aoyi, Ochieng
    Textile industry effluents are carcinogenic and highly recalcitrant hence difficult to degrade especially through biological methods. Abattoir effluents are classified under high-strength wastewaters because of their characteristic high organic load hence highly biodegradable. Anaerobic co-digestion is the concept of degrading two effluent streams with complementary characteristics in order to improve the substrate removal rate. The feasibility of co-digesting abattoir and textile wastewater in a UASB reactor was evaluated at mesophilic and ambient temperature conditions. Preliminary experiments were conducted in 500 ml batch reactors to evaluate the optimum abattoir to textile synthetic wastewater ratio. The effect of COD, TVFA, alkalinity and pH on biogas yield was examined at both ambient and mesophilic temperatures. Anaerobic co-digestion of abattoir to textile wastewater in the ratio determined in the batch process was carried out in a 3 L UASB reactor by a continuous process. The continuous biodegradation process was executed at three different HRTs (22, 18 and 14 hrs) over a 60 day operation period. UASB reactor efficiency was achieved at organic loads ranging from 3.0 – 10.8 gCOD L-1 day-1. Continuous mode experiments were carried out at influent flow rates which corresponded to HRTs ranging between 1 to 8 days in order to evaluate the steady state operating parameters for the co-digestion process. The abattoir to textile effluent ratio was found to be 60:40 respectively. The COD, TVFA, alkalinity and pH and biogas yield followed a similar pattern over time at both mesophilic and ambient temperature conditions. Experimental data adequately fit the Grau first order kinetic model and average COD removal efficiencies of 85% and BOD5 of around 96% were achieved. The average biogas yield remained essentially constant, around 0.19 L/g CODremoved. The co-digested mixture was found to be biodegradable judging from the BOD:COD ratio of 0.53. TCOD removal efficiency decreased from 93% to 16% as HRT decreased from 8 days to 1 day. The kinetics of a UASB reactor co-digesting the mixture of synthetic abattoir and textile wastewater was evaluated in this study using Grau second order multicomponent substrate removal kinetic model. The Grau second order kinetic model, whose kinetic coefficient (ks) was 0.389, was found to be suitable for predicting the performance of a lab-scale UASB reactor.
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    Design and development of an off-grid e-learning centre for rural communities
    (2015-01) Selaule, Vusimuze Edgar; Schoeman, R. M.; Pienaar, H. C. v Z.
    The lack of electricity in off-grid rural communities in South Africa (SA) and Africa as well as the budget constraints on these communities restrict these communities from connecting to any online resources (internet and e-books) for educational purposes, thus creating a major contributor to the global digital divide. Renewable energy sources such as solar energy, wind energy and biomass were presented as potential alternatives to grid-connected electricity for remote rural locations. Solar energy was identified as the amply available alternative energy resource in SA. Solar radiation was converted by photovoltaic technology to electricity. National power grid isolation (off-grid) was achieved by using a stand-alone photovoltaic system. Photovoltaic technology classification, material categorisation and system sizing for an e-learning centre was presented. Practical set-ups were utilised to determine the most cost-effective equipment mix of power utilization, power management/storage and ICT equipment to build a pilot e-learning centre. It was established that one photovoltaic panel can be employed to fully recharge a battery of a pilot e-learning centre with an operational period of 7 hours using the available sunlight hours. Owing to the susceptibility of the Vaal Triangle region to thunderstorms causing overcast conditions for days, a ratio of back-up battery capacity (Ah) to number of days (seven hours per day) without sunlight was determined. An algorithm was also derived for sizing the pilot e-learning centre for full scale implementation. Future research recommendations based on this study for a reduced system costs of an off-grid e-learning for rural communities powered by a renewable energy resource were presented. This will increase access to basic education in SA and reduce the global digital divide.
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    Characterization and identification of microbial communities in pigeon droppings using Culture-Independent techniques
    (Vaal University of Technology, 2015-08) Leareng, Samuel Keeng; Feto, Naser Aliye, Dr.; Pillay, M., Prof.
    Pigeon droppings, found in abundance in most cities and towns where pigeons are found, are a source of potential yeast and molds into the environment. Invasive fungal infections are a cause of morbidity and often mortality in immunocompromised individuals. The objective of this study was to the identification of bacterial and mold agents from pigeon droppings. Pigeon droppings samples were collected from three locations during the winter and summer months and studied for the occurrence of bacteria, yeast and molds by utilising culture-independent techniques. Amplification of the 16S rDNA gene and the internal transcribed spacer (ITS) region, cloning and ARDRA and DGGE were used for the characterisation of the microbial populations followed by sequencing. Several mold and yeasts, as well as bacteria were found to be present in pigeon droppings, which can spread into the environment and be transmitted to immunocompromised individuals and children. DGGE analysis of the bacterial communities revealed banding patterns that clustered all but one winter samples and all summer samples, showing a high similarity among the microbial members in both seasons and sample locations. Fungal DGGE analysis revealed clusters that grouped summer and winter samples from Johannesburg and Pretoria while VUT samples were clustered on their own. From the identification of fungal and bacterial DNA, Cryptococcus species was the majority of fungi isolated from the dropping samples. Geotrichum, Kazachstania and Fusarium species were isolated from phylotypes obtained from ITS amplicons analysed by ARDRA. Lactobacillus and Enteroccoccus species, organisms usually found in the gastrointestinal tract were the common bacterial members identified. The results showed no difference in microbial communities across all sample locations, while seasonal changes also had no impact in microbial community patterns.
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    Screening of substituted pyrazolone and pyrazole as ligands with palladium precursors in the Heck reaction
    (2015-03) Bout, Wanda; Nelana, S. M.; Mtunzi, F. M.
    The arylation and alkenylation of alkenes under the influence of a palladium catalyst, commonly referred to as the Heck reaction, has been extensively exploited by synthetic chemists since its debut in the late 1960’s. A traditional Heck coupling is based on an aryl iodide or bromide as the electrophilic partner and a terminal alkene as the nucleophilic partner. Academic and industrial interest in this reaction has increased in recent years, fueled by the development of more active catalyst systems, the discovery of waste-free versions, and the desire to put the vast empirical data on a sound mechanistic basis. In this study, we wish to report the use of commercially available substituted pyrazolones (1-(4-Sulfophenyl)-3-methyl-5-pyrazolone (L1), 1-(2,5-Dicloro-4-sulfophenyl)-3-methyl-5-pyrazolone (L2) and 5-oxo-1-phenyl-2-pyrazolin-3-carboxylic acid (L3)) and pyrazoles (α-[(2-Ethoxy-2-oxoethoxy)imino]-3-pyrazole acetic acid (L4) and 3.5 dimethyl pyrazole (L5)) as auxiliary ligands in the Heck coupling reaction. These ligands were used either with PdCl2 or Pd(OAc)2 to catalyze the Heck reaction of iodobenzene with ethyl acrylate or butyl acrylate. GC-MS was used to monitor the reaction, percentage (%) conversions were determined based on the consumption of iodobenzene. Different reaction parameters such as ligands, temperature, base, solvent and influence of time were investigated. It was observed that the lower conversion was obtained for ethyl acrylate and conversions above 80% were obtained for butyl acrylate. Ligand effect proved to be very crucial during the Heck coupling reactions of iodobenzene with butyl acrylate and ethyl acrylate. For instance in the absence of ligands with PdCl2, the conversions were 29 % and 44 % for butyl acrylate and ethyl acrylate, respectively. When Pd(OAc)2 was used in the absence of ligands the conversions were 25 % and 36 % for butyl acrylate and ethyl acrylate, respectively. In the study for the effect of temperature, 80 ◦C was observed as the best temperature since promising conversions were obtained with little or no sign of deactivation of the catalysts. On the other hand, increasing the temperature to 120 ◦C and above high percent conversions are observed; however deactivation of the catalysts occurs as observed from the precipitation of palladium black at the bottom of the vial. From the results obtained it is clear that pyrazolone and pyrazole ligands/palladium systems are important at very low catalyst loadings and mild temperatures. Based on the employed reaction conditions the influence of base suggested that the organic base triethylamine was the reagent of choice since better conversions were obtained compared to inorganic bases. The inhomogeneity of the inorganic base proved to be a disadvantage in the reaction of iodobenzene with butyl acrylate at employed reaction conditions. It was also found that parameters such as solvents and time effects were important in the Heck reaction. Polar aprotic solvents proved to be solvents of choice rather than non-polar solvents, from the investigated solvents DMF gave better conversions under the used reaction conditions giving average conversions of 78 % and 75 % for all the ligands in the presence of PdCl2 and Pd(OAc)2, respectively. During the investigation of time effect, it was noteworthy to observe that L4 had a slow initiation rate, for instance after 0.5 h conversions of 2 % and 10 % were obtained for catalytic systems, PdCl2 and Pd(OAc)2 respectively. Also it was observed that under the investigated parameters there was no need to run the reaction for 24 h because after 4 h not much of a difference in conversions was observed. In comparing the influence of these two different auxiliary ligands, pyrazolone based ligands were more efficient than pyrazole based ligands under the investigated parameters. The fully detailed information supporting this has been discussed in Chapter 4.
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    Job satisfaction and the intention to quit by employees in a steel manufacturing company in Gauteng
    (2015-09) Mgiba, Steven; Joubert, P. A.
    The main purpose of the study was to examine the level of job satisfaction and intention to quit, by employees in a steel manufacturing company. The research methodology used to conduct the study was a combination of a literature review and an empirical study. Due to the small size of the population, no sampling was done although a census had been drawn. The primary data were collected using a structured questionnaire. The measuring instrument contained 25 items. For the main survey, data from 181 respondents were collected and analysed. Participants in the study involved engineers, operators, technicians, artisans, administrative staff and safety, health and environmental specialists in the steel manufacturing company. Data were analysed with the Statistical Package for Social Sciences (SPSS) version 20.0. The Cronbach’s alpha coefficients of the measuring instrument were computed to establish construct validity. Content validity of the scale was ascertained by pre-testing the questionnaire with employees in the steel manufacturing company. Factor analysis was conducted for variables in Section B of the research instrument. Analysis was done using descriptive statistics on the demographic information of respondents. The results were also interpreted through the factor analysis and correlation analysis. The findings regarding employee’s perceptions or feelings about job satisfaction and employees’ intentions to quit their current organisation revealed that the supervision variable is positively correlated with job variable while it is negatively correlated with intention to quit. In addition, job variable is also negatively correlated with intention to quit. This means that effective supervisors are likely to improve employees’ job satisfaction hence decrease their intentions to quit their current organisation and vise versa. In addition, when employees are satisfied with their job environment, this will decrease their intentions to quit their current organisation and vise versa. Judging from the results from respondents, it is clear that when employees are provided with a job that rewards them for their effort and provides opportunities for advancement, they will be satisfied and therefore more likely to stay in the organisation. Hence, the employees at Babcock Ntuthuko Generations are satisfied and they are not intending to leave the organisation. The research information collected through this study can be used to encourage Babcock Ntuthuko management to continue providing employees with a conducive working enviroment to ensure that current and new employees are retained.
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    Treatment of acid mine drainage using constructed wetland and UV/TiO₂ photocatalysis
    (2014-05) Seadira, Tumelo Wordsworth Poloko; Aoyi, Ochieng
    Acid mine drainage (AMD) is a serious problem associated with mining activities, and it has the potential to contaminate surface and ground water. The aim of this study was to evaluate the performance of constructed wetland and photocatalysis in treating AMD. Three identical unvegetated upflow constructed wetlands packed with natural zeolite (clinoptilolite) and coarse silica sand were made of a cylindrical plastic pipe, and the slurry photocatalyst was prepared using quartz material. A hydro-alcohol thermal method was used to prepare an anatase core-void-shell TiO2 photocatalyst. The results showed that the three unvegetated upflow constructed wetlands (CW) had relatively similar percentage removal of heavy metals despite their varying concentrations within the AMD. The removals were: Fe (86.54 - 90.4%); Cr (56.2 - 64.5%); Mg (56.2 - 67.88%); Ca (77.1 - 100%); and 100% removal was achieved for Be, Zn, Co, Ni, and Mn. The removal of sulphate was also 30%. Heavy metals concentration in CW packing material was significantly higher in the outlet of the constructed wetlands than in the inlet. The adsorption isotherms revealed that the experimental data fitted the Langmuir Isotherms better, which suggested a monolayer coverage of heavy metals on the surface of the adsorbents; thermodynamic studies showed that the nature of adsorption taking place was physical; the kinetics models showed that the adsorption was first order reaction. A higher photocatalytic reduction (62%) of Cr(VI) was obtained at pH 2, 30 mg/l Cr(VI) initial concentration, and three hours of irradiation time. It was also found that the presence of Fe(III) enhanced the reduction of Cr(VI). The core-void-shell TiO2 photocatalyst showed a better activity than the commercial P25 Degussa for the reduction of Cr(VI) to Cr(III). The kinetic studies showed that the reduction of Cr(VI) was first order reaction. Photocatalytic reduction of Cr(VI) in real AMD sample was achieved only for the Douglas North Discharge (DND) sample (68%), and the Fe(III) reduction was found to be 83%. Therefore it was concluded that the combination of constructed wetland and UV/ TiO2 photocatalysis employing anatase core-void-shell TiO2 as a photocatalyst has a potential to reduce the toxicity of Cr(VI)-laden acid mine drainage.
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    An intelligent automatic vehicle traffic flow monitoring and control system
    (2015-01) Marie, Theko Emmanuel; Gatsheni, B. N.
    Traffic congestion is a concern within the main arteries that link Johannesburg to Pretoria. In this study Matlab function Randperm is used to generate random vehicle speeds on a simulated highway. Randperm is used to mimic vehicle speed sensors capturing vehicle traffic on the highway. Java sockets are used to send vehicle speed to the Road Traffic Control Centre (RTCC)-database server through a wireless medium. The RTCC-database server uses MySQL to store vehicle speed data. The domain controller with active directory together with a certificate server is used to manage and provide security access control to network resources. The wireless link used by speed sensors to transmit vehicle speed data is protected using PEAP with EAP-TLS which employs the use of digital certificates during authentication. A java database connectivity driver is used to retrieve data from MySQL and a multilayer perceptron (MLP) model is used to predict future traffic status on the highway being monitored i.e. next 5 minutes from previous 5 minutes captured data. A dataset of 402 instances was divided as follows: 66 percent training data was used to train the MLP model, 15 percent data used during validation and the remaining 19 percent was used to test the trained MLP model. An excel spreadsheet was used to introduce novel (19 percent data not used during training) data to the trained MLP model to predict. Assuming that the spreadsheet data represent captured highway vehicle data for the last 5 minutes, the model showed 100 percent accuracy in predicting the four classes: congested, out congested, into congested and normal traffic flow. Predicted traffic status is displayed for the motorist on the highway to know. Ability of the proposed model to continuously capture the traffic pattern on the highway (monitor) helps in redirecting (controlling) the highway traffic during periods of congestion. Implementation of this project will definitely decrease traffic congestion across main arteries of Johannesburg. Pollution normally experienced when cars idle for a long time during congestion will be reduced by free highway traffic flow. Frequent servicing of motor vehicles will no longer be required by the motorists. Furthermore the economy of Gauteng and South Africa as a whole will benefit due to increase in production. Consumers will also benefit in obtaining competitive prices from organizations that depend on haulage services.
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    A comparative analysis of the effective use of transfer pricing policies in multinational manufacturing corporations in Southern Gauteng
    (2016-04) Siewe, Constantain Lendeu; Ziemerink, J. E. E.; Beneke, J. D.
    This study was undertaken to assess the extent to which transfer pricing was effectively used by multinational manufacturing companies operating in the Southern Gauteng region of South Africa. The target participants of the study traded their products across international borders and as such made use of transfer pricing in one way or the other to achieve strategic objectives. Scant research has been undertaken to analyse the degree to which transfer pricing can be used to effectively influence managerial performance. On the other hand there is a wealth of knowledge on the relationship between transfer pricing and taxation. In-depth review of literature showed that even though multinationals formulated their transfer pricing policies to target financial and managerial objectives, self-interest and outside influences tended to hinder the equitable realization of both types of objectives. The study therefore set out to establish whether this is true of Multinational corporations (MNCs) in Southern Gauteng and in the process answer questions about the procedure for formulating transfer pricing policies by these MNCs, the relationship, if any, between transfer pricing and profitability and the use of transfer pricing for performance enhancement and assessment. The study made use of a mixed methods research methodology to collect and analyze data from 45 MNCs operating in the target geographical area. Of the 45 companies, 15 cooperated fully with the study. Data was collected via the use of questionnaires and follow-up face-to-face and/or telephonic interviews. Collected data was analysed using statistical methods including the Chi Square Test, standard deviation, frequency tables and the Kruskal-Wallis H test. The results from the questionnaire and interviews show that there is no universally appropriate Transfer Pricing Policies(TPP) which applies equally to all organizations in all circumstances. Firms are affected by different environmental factors while striving for tax-compliance and value creation. The fear of falling on the wrong side of tax laws is a major driving force behind transfer pricing policies of MNCs. As such other objectives that are managerial in nature become secondary and tend to be neglected if/when they conflict with the primary objective.
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    Treatment of process water at Dense Media Separation (DMS) Powders Industry using selected membrane processes
    (2015-07) Mosia, Mmankaeya Elsie; Modise, S. J.; Sipamla, A. M.
    There is huge concern in the mining and industries to manage wastewater prior to discharge into the environment. It is generally cheaper and cost reducing for industries to treat its own wastewater before discharging to the local authority sewer. Dense Media Separation (DMS) Powders Company produces milled and atoms ferro-silicon by pyro-metallurgical process. DMS Powders uses municipal water for all processes taking place in the plants. The water used during the processes of milled and atom ferrosilicon powder is discharged into the environment without being treated. By treating this process wastewater before discharging will result in reducing the water consumption by recycling and the penalty costs for polluting the environment. The primary objective of this study is to find suitable method for treatment of DMS Powders’ process water using selected membrane processes. Membrane processes are better choice compared to traditional physical/chemical treatment processes, due to their advantages of approving water quality, no phase change, no chemical addition and simple operation. Two commercial membranes namely; NF-, and SW30HR are used in the treatment of DMS Powders process water. These membranes were purchased from (Dow/Filmtec) Manufacturing Company (Pty) situated in South Africa. Membranes were characterised by Scanning Electron Microscopy (SEM), Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA) and Fourie Transform Infrared (FTIR) instruments. For synthetic water three membranes (NF- , NF90, and SW30HR) are investigated for the study. The fluxibility indicated that NF- membrane has higher flux compared to NF90 and SW30HR membranes. All the three membranes were very good in terms of rejection on single salts. Fouling was studied on DMS Powders process water. Concentration polarization was formed on NF- and SW30HR membranes investigations on selected membranes conclude that NF- membrane will be the suitable membrane for treatment of DMS Powders process water because of its high fluxibility and rejection. Discharged effluent of DMS Powders could comply with the legislature and environmental pollution could be minimised. The study revealed that fouling does occur during treatment of process water. SW30HR showed that M9 Plant had more fouling for M9 samples than other Plants (M8A and M8B). It was because of higher concentrations in suspended solids.or M8A, M8B and M9 process water.
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    Employees' adherence to the Occupational Health and Safety Act in the steel manufacturing sector
    (2016-09) Mojapelo, Jerry; Dhurup, M.
    Industrial accidents have proved to be more prevalent and costly than anticipated especially in developing countries including South Africa. Occupational accidents have direct and indirect cost implications for an organisation as well as society. Governments in many countries have tried to implement legislation to try and curb the scourge of industrial accidents. The primary purpose of this research was to investigate the level of employee adherence to the Occupational, Health and Safety Act (OHSA) 85 of 1993 in the steel manufacturing sector. This research provided an overview of various factors that influences employee’s level of understanding and adherence to the OHSA. This included factors such as information and training in health and safety; employee safety perception, employee safety awareness, employee safety adherence, employee behaviour with regard to health and safety, the role of the union in health and safety issues, accident reporting mechanism, and employee’s perceptions of the influence of rewards on health and safety. A structured questionnaire consisting of closed-ended questions was developed and disseminated in order to gather relevant data. Given the scale of the research, a quantitative research method was implemented. The population for the study strictly consisted of employees working in the steel manufacturing sector. A purposive sampling technique was selected. Statistical Package for Social Sciences 22.0 (SPSS) was used to analyse the data. The sample size of (n) =165 employees was involved in the study. The response rate for the total was (98.5%). Descriptive, frequency, correlation, regression and means analysis was employed in this study. The results of the study indicated that majority of the employees were aware and adhered with the requirements of the OHSA with the organisation. It was suggested that strong stake holder partnerships between unions, employers and employees be formulated. The state should reinforce the Department of Labour inspectorate by giving it more powers to be able to execute its task meritoriously and efficiently. It further suggested that the state must rapidly focus on recruiting and training more health and safety labour inspectors to ensure appropriate enforcement of health and safety regulations. Lastly it is advisable to create and engrave a health and safety culture within the organisation that focuses on highly on employee involvement and mutual trust. The proposed recommendation for the study, limitations and the conclusion of the study were outlined in Chapter 5.
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    An analysis of capital structures of listed industrial companies in South Africa
    (2016-08) Popoola, Babatunde Adedeji; Beneke, J. D.; Ziemerink, J. E. E.
    This study examines the capital structure theories, specifically the trade-off theory and the pecking order theory. It also analyses the influence of the capital structures choice among 72 listed industrial companies on the Johannesburg Stock Exchange ltd (JSE) in South Africa from 2005-2013 to determine whether these firms follow the trade-off theory or the peckingorder theory. The external database (INET BFA) was used to obtain the data needed for the statistical analysis. From the database, annual standardised financial statements, statement of comprehensive income, cash flow statements, financial ratios, statement of change in equity and the retained earnings to debt ratio of all the listed industrial companies in South Africa from 2005- 2013 were extracted in order to enable the conducted research. A multiple regression and correlation analysis were carried out the with leverage ratio (trade-off theory) and the retained earnings to debt ratio (pecking order theory) as the independent variables and share price as the dependent variable, in order to examine which of the two theories is closely related to share prices in South Africa. Furthermore, a multiple regression and correlation analysis was also done with common shares issued, retained earnings, long-term debt and weighted average cost of capital as the independent variables and share price as dependent variable, to determine if there is a relationship between the capital structure and share prices of the listed industrial company. The results indicated that there were little or no influence of capital structure theory on share prices, the financing practices and the performance of listed companies in South Africa. This indicated that industrial companies in South Africa rarely practice capital structure in accordance with the capital structure theories. Moreover, retained earnings and long-term debt have a positive influence on the performance of listed industrial companies in South Africa from 2005-2013.
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    Synthesis of cross-linked pine cone biosorbent and its applications in industrial wastewater treatment
    (2014-11) Kupeta, Albert Jerry Kafushe; Ofomaja, A. E.; Naidoo, E. B.
    The widespread use of phenols and phenolic derivatives in industrial applications has resulted in their discharge as part of industrial wastewater. These chemicals are toxic and need to be removed from the aqueous environment. Amongst the available pollutant removal technologies, adsorption has been widely used due to its simplicity, ease of operation, cost-effectiveness and ability to sequester pollutants at very low concentrations. Different adsorbents have been applied for removal of phenols and their derivatives. Use of agricultural waste as adsorbents seems to offer a much cheaper alternative in pollutant removal. This study examines the synthesis of a hydrophobic biomaterial composite by cross-linking of Fenton treated pine cone and applying the prepared adsorbent for 2-nitrophenol removal from aqueous solution. Pine cone biomass, in its raw and modified forms was tested for its ability to remove 2-nitrophenol from simulated industrial wastewater. The experimental procedure is divided into two main parts: (1) pine cone modification using Fenton’s reagent and 1.6-hexamethylene diisocyanate and (2) application of the prepared hydrophobic adsorbent for 2-nitrophenol removal from wastewater. Fenton’s reagent was used to remove pigments, extractives and other soluble organic compounds from the raw pine. FTIR spectroscopy showed an increase in magnitude of oxygenated surface groups which resulted in a decrease in pHpzc. The effect of Fenton treatment on further modification of the pine biomass via cross-linking using 1.6-hexamethylene diisocyanate was investigated. Optimum reaction variables for the cross-linking using dibutyltin dilaurate as catalyst under an inert nitrogen gas atmosphere in anhydrous hexane solvent were determined using FTIR spectroscopy. Success of the cross-linking procedure was confirmed by use of analytical techniques (XRD, TGA, SEM, EDX and BET surface area) and weight percent gain calculations. Pine and modified pine biomass were tested for their ability to sequester 2-nitrophenol via batch adsorption technique. The effect of pine modification on affinity for the biosorbate was investigated. The mechanism of the adsorption process was determined via use of kinetic, diffusion and equilibrium isotherm models. Two error functions (coefficient of determination and percent variable error) were employed to substantiate the model showing a good fit to the experimental adsorption data. The experimental adsorption kinetic data was fit to the pseudo-first-order and pseudo-second-order kinetic models. Due to the large size of the pollutant molecules diffusion process analysis was also conducted. The effect of pine modification on kinetic and diffusion parameters was determined. The experimental equilibrium adsorption data was fit to the Freundlich, Redlich-Peterson and Hill isotherm models. The initial shapes of the adsorption isotherms for 2-nitrophenol adsorption onto pine and modified pine biomass determined the type of equilibrium isotherm models to fit the experimental data to. Thermodynamic parameters were calculated to determine the spontaneity, feasibility and energy changes associated with the adsorption process. The degree of disorder at the solid/liquid interface after the adsorption was determined. The effect of temperature on the adsorption process was used to show whether the adsorption is physical or chemical. The effect of pine modification on equilibrium isotherm parameters was determined. The study is divided into seven chapters: Chapter 1: The chapter covers the introduction, problem statement, aim and objectives of the research. It gives an insight into the research project. Chapter 2: The literature review of pollutants in industrial wastewater and methods of their removal is dealt with in this chapter. Adsorption is introduced as an alternative technique for pollutant removal from aqueous systems. An in-depth review of various adsorbents (including pine cone), their merits and limitations are also discussed together with methods of modifying and use of modified adsorbents. Equilibrium, kinetic and thermodynamic models used to treat adsorption experimental data are presented. Chapter 3: The experimental procedures on the synthesis, characterization and application of the hydrophobic biosorbent in the removal of 2-nitrophenol from aqueous solution are presented. Kinetic and equilibrium experiments are described in detail. Chapter 4: It describes the first part of the results and discussions. The chapter focuses on optimization of reaction variables and characterization (using various analytical techniques) of the hydrophobic biomaterial composite. Chapter 5 The chapter discusses the second part of the results. It focuses on magnitude of surface charge, pHpzc and kinetic studies. Fitting of the adsorption experimental data to kinetic and diffusion models is presented together with the error functions. Chapter 6 The chapter discusses part three of the results on equilibrium studies. The adsorption experimental data is fitted to equilibrium isotherm equations and error determination is presented. Thermodynamic parameters are calculated and interpreted. Chapter 7: Conclusion and recommendations are presented. The optimum reaction variables for cross-linking of Raw and Fenton treated pine cone were determined using FTIR analysis and found to be: 0.2 g pine biomass, 3.5 cm3 1.6-hexamethylene diisocyanate cross-linker, 50 cm3 anhydrous hexane solvent, 1.5 cm3 dibutyltin dilaurate catalyst, temperature of 50 °C and a reaction time of 4 hours. The pine surface showed an increase in phenolic, lactonic and carboxylic acid groups due to the modification. The pHpzc showed a decrease due to modification of the pine cone biomass. The pHpzc values for the pine and modified pine cone biomass were found to be: Raw = 7.49, Raw-HMDI modified = 6.68, Fenton treated pine = 5.40 and Fenton-HMDI modified = 6.12. The optimum pH for the adsorption of 2-nitrophenol onto raw pine and modified pine cone biomass was determined to be 6. The optimum adsorbent dosage was determined as 1.5 g/dm3. The adsorption kinetics show a good fit with the pseudo-second-order model. This suggests that surface adsorption is the controlling step in the adsorption of 2-nitrophenol onto pine cone biomass. The analysis of diffusion processes showed that the initial rapid stage during the adsorption is due to external mass transfer processes. The adsorption experimental data also showed that pore diffusion was rate-limiting amongst the diffusion processes. Pine modification using Fenton’s reagent and 1.6-hexamethylene diisocyanate increased magnitude of kinetic and diffusion parameters. Experimental data for 2-nitrophenol adsorption onto pine and modified pine cone biomass showed better correlation with the Redlich-Peterson and Hill isotherm models and poor correlation with the Freundlich isotherm model. This suggests that the mechanism does not show complete multilayer coverage with cooperative phenomena between adsorbate molecules. Thermodynamic parameters showed that the adsorption is feasible, spontaneous, and exothermic and results in a decrease in degree of disorder at the solid/liquid interface. An increase in temperature resulted in a decrease in adsorption capacity showing that the adsorption is physical. Pine modification using Fenton’s reagent and 1.6-hexamethylene diisocyanate increased magnitude of kinetic, diffusion and isotherm parameters. The kinetic and equilibrium results show that the adsorption of 2-nitrophenol onto pine cone biomass follows the order: Fenton treated-HMDI > Fenton treated > Raw-HMDI > Raw. Hence, it can be concluded that Fenton treatment and HMDI cross-linking modification did increase the adsorptive capabilities of the pine cone biomass.
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    Succession planning: current practices, internal succession barriers and the relationship with intentions to leave within a public service in a developing country
    (2015-09) Pita, Nomalinge Amelia; Dhurup, M.; Joubert, P. A.
    In today’s globally competitive and modern environments, organisational plans often fail due to the lack of succession planning. However, numerous organisations often fail to prepare for the inevitable departure of employees, especially in strategically high-level positions. Succession planning is a means of identifying critical management positions starting at lower level management and extending up to the highest position in an organisation. Unlike workforce planning, succession planning focuses more on advancing the employees’ skills in order to achieve the organisational objectives. There is no organisation that can exist forever in its present composition as there must be some form of succession or else the organisation will become obsolete. Succession planning plays an imperative role in today‘s competitive world. There are many factors that influence the stability of an organisational workforce, among which are illness and attrition. Another essential factor, which has taken the world by storm, is the retirement of the baby boomer generation in both in the private and the public sector. This is presenting a challenge within organisations, as they are going to lose talented and experienced employees and makes succession planning more needed more than ever before. Succession planning is an ongoing process that assists the organisation to align its goals with its workforce, as well as preserving the best talent for the future. It makes the organisation ready to face the challenges presented by the vacant key and critical positions. Succession planning is one of those human resource planning strategies utilised to forecast the talent demand that the organisation will require for achieving its future goals. The main purpose of this study was to examine the succession planning current practices and internal succession barriers, and determine their relationship with intentions to leave within the public service of a developing country. The research methodology used to conduct the study is a combination of a literature review and an empirical study. The probability sampling technique, which involves using simple random sampling, was utilised to select the sample for the study. The primary data were collected using a structured questionnaire. The measuringinstrument contained 25 items. The instrument was pilot-tested with 87 respondents one month prior to the main survey. The questionnaire was hand delivered to all the participants. For the main survey, data from 250 respondents were collected and analysed. Participants in the study involve officers, managers and directors in the public service of a developing country. Data were analysed with the Statistical Package for Social Sciences (SPSS) version 20.0. The Cronbach’s alpha coefficients of the various sections of the measuring instrument were computed to establish construct validity. Content validity of the scale was ascertained by pre-testing the questionnaire with employees in the public service. Exploratory factor analysis was conducted for variables in Section B of the research instrument. Convergent validity was assessed through correlation analysis using Pearson’s correlation coefficient in order to establish relationships between succession planning current practices and intentions to leave, as well as between internal succession barriers and intentions to leave the public service. Analysis was done using descriptive statistics on the demographics information of respondents. The results were also interpreted through the exploratory factor analysis, correlation and regression analysis. The results showed that two major factors of succession planning, namely replacement planning and grooming, correlate negatively with intentions to leave. The internal succession barriers also have a negative correlation with intentions to leave. Subsequent to these findings, it is recommended that the public service implement succession planning appropriately and eliminate the barriers thereof in order to retain its workforce. Based on the findings emanating from the empirical survey it was revealed that if succession planning is implemented appropriately and factors such as replacement planning and grooming are taken into consideration, employees holding key positions may be likely to be retained. Therefore, it was recommended that prior to undertaking succession planning a mission, vision and values that accommodate the contributions of employees should be developed. It was recommended also that when implementing succession planning, clear, transparent and objective criteria should be followed to achieve the optimal results. It is further recommended that the following succession planning best practices should be adopted by the public service to ensure that succession planning is implemented and practised successfully: Facilitation of an outside private consultant − for succession planning to be effective and rewarding in the public service it should be facilitated by an outside private consultant. Understanding of factors that influence succession planning − the public service should understand the necessity to know and address factors that influence willingness to share knowledge by employees. The study concludes by recommending that barriers that hinder succession planning should be avoided by adhering to the following suggestions: Longer terms of appointment should be provided for top public service employees Succession planning should be listed as one of the priorities in the public service strategic plan in order to be included in the budget Young vibrant and competent employees be motivated, groomed and prepared to apply for leadership or key positions in the public sector
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    The influence of rewards on talent attraction and retention at a further education and training college in Gauteng
    (2015-10) Mabaso, C.; Moloi, K. C.; Joubert, P. A.
    The purpose of this study is to investigate the influence of employee rewards on talent attraction and talent retention. Furthermore, the study intends to unearth the influence of rewards on employee attraction and retention and to suggest strategies that could be employed by FET colleges in Gauteng in the Sedibeng district of Gauteng. The attraction and retention of employees continues to be a key priority not only of human resource professionals but also of FET colleges generally in South Africa and in the Gauteng province in particular. The most valuable asset available to an organisation is its people, and consequently, retaining employees in their jobs is crucial for any organization. In South Africa, the retention of highly skilled employees is critical, particularly because of the need to contribute to economic growth, innovation and poverty eradication. Owing to the competition for scarce skills, the attraction and retention of quality employees has emerged as the biggest challenge in human capital management and this phenomenon has also arisen in FET colleges. To attract and retain employee, organisations need novel reward systems that satisfy employees. This study employs a quantitative research paradigm and a survey method was used to investigate a sample of 154 academic employees at Sedibeng FET College, Gauteng. A personal method was used to collect data using semi-structured questionnaire and the results of the correlations shows that employee rewards are significantly positively related to talent attraction and talent retention. Findings and recommendations of this study are important to employers as they are supposed to design a remuneration package that attract and retain the best candidates and satisfies their employee’s expectations, in that it is fair, equitable and free of bias. A remuneration package is one of the most important factors that influence people to take up employment and stay with the organization.
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    Semantic knowledge extraction from relational databases
    (2014-05) Mogotlane, Kgotatso Desmond; Fonou Dombeu, Jean Vincent
    One of the main research topics in Semantic Web is the semantic extraction of knowledge stored in relational databases through ontologies. This is because ontologies are core components of the Semantic Web. Therefore, several tools, algorithms and frameworks are being developed to enable the automatic conversion of relational databases into ontologies. Ontologies produced with these tools, algorithms and frameworks needs to be valid and competent for them to be useful in Semantic Web applications within the target knowledge domains. However, the main challenges are that many existing automatic ontology construction tools, algorithms, and frameworks fail to address the issue of ontology verification and ontology competency evaluation. This study investigates possible solutions to these challenges. The study began with a literature review in the semantic web field. The review let to the conceptualisation of a framework for semantic knowledge extraction to deal with the abovementioned challenges. The proposed framework had to be evaluated in a real life knowledge domain. Therefore, a knowledge domain was chosen as a case study. The data was collected and the business rules of the domain analysed to develop a relational data model. The data model was further implemented into a test relational database using Oracle RDBMS. Thereafter, Protégé plugins were applied to automatically construct ontologies from the relational database. The resulting ontologies are further validated to match their structures against existing conceptual database-to-ontology mapping principles. The matching results show the performance and accuracy of Protégé plugins in automatically converting relational databases into ontologies. Finally, the study evaluated the resulting ontologies against the requirements of the knowledge domain. The requirements of the domain are modelled with competency questions (CQs) and mapped to the ontology using SPARQL queries design, execution and analysis against users’ views of CQs answers. Experiments show that, although users have different views of the answers to CQs, the execution of the SPARQL translations of CQs against the ontology does produce outputs instances that satisfy users’ expectations. This indicates that Protégé plugins generated ontology from relational database embodies domain and semantic features to be useful in Semantic Web applications.