Faculty of Applied and Computer Science

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Computer literacy as additional empowerment mechanism in learning programmes
(2004-01) Van Staden, A; Hoffmann, E. C.
The world of digital interactivity, of computers, of cyberspace and the "e-revolution', is making computer literacy more indispensable than ever. There is an increasing demand for ICT skills worldwide- South Africa is not alone in identifying shortages. The information and communication technology in South Africa is exacerbated by emigration on the one hand and the previously disadvantaged learners on the other hand. With an education system that is stretched, higher education has not kept pace with information and communication technology training in South Africa, therefore learners display a shortcoming of basic computer skills. The purpose of this study is to emphasise the importance of implementing computer literacy training throughout the entire learning programme of learners at higher education institutions. Learners randomly selected from the Faculty of Management Sciences, Vaal University of Technology, indicated their computer literacy via questionnaires and levels of experience. It is clear that the abilities of the learners are not sufficient to ensure that they are computer literate or that they will be effective users in the workplace. This study results in a powerful argument in support of the extension of continued growth in computer usage in the workplace.
Secretary versus office manager : a paradigm shift
(2004-02) Wilkinson, Judith Levine; Garnett, A; Buys, C.
The objectives of this research project were primarily to determine the requirements of commerce and industry for competent office managers, to contribute to the curriculum development of information administration, to facilitate action learning (AL) in information administration, and by making changes in training to empower learners to become competent office managers. The influence of training and development of office managers is explained. The National Qualification Framework (NQF) integrates training and education in business and management on all levels. An important aspect is, that professional institutes, education and training institutions and other stakeholders, are combining experience to collectively benefit learners, employers, professions and the economy as a whole. A combination design of both quantitative (traditional) research and qualitative (action) research, including two questionnaires (open-ended and closed), interviews, observations, focus groups and a case study, were used. This study proved the relevance of office management education, by way of the demand for a formal qualification by commerce and industry, as a primary result of the phenomenal change in technology and the need for multi-skilled office managers. A contribution to the training of office managers concerning the following aspects was made: A profile for an office manager, as well as highlighting the need for training, curriculum development, and portfolio development
Combating the corporate paper war: optimising electronic mail and electronic filing
(2006-11) Bothma, Marchelle Marelize; Hoffmann, E. C.
The primary objective of this research project was primarily to investigate filing methods and mailing practices in the computer support or administrative environment with specific focus on the abuse of paper. The research design consisted of an exploratory investigation in selected Higher Education Institutions in the Province of Gauteng whereby a structured questionnaire was used as a measuring instrument. The investigation was sub-divided into two categories, namely, paper-based filing systems and mailing systems as opposed to electronic filing and mailing systems. In the empirical findings, analysis and interpretations, correlation and cross-tabulation were done on all sets of variables in order to determine whether any meaningful associations could be found. With reference to the title of this study "Combating the corporate paper war: optimising electronic mail and electronic filing", it has been proven that the war against paper abuse is far from over. Perceptions regarding a future paperless office and assumptions that technology such as the electronic mail facility and electronic filing could assist organisations to combat paper abuse were unfounded, due to a lack of guidance and control measures in the corporate environment. Consequently, it is recommended that an e-filing and e-mailing model be created and followed in conjunction with specified computer software features in order to counteract the abuse of paper. Follow-up research could focus on electronic filing methods versus scanning of documents for filing purposes.
A model to reduce the divide between South African secondary institutional skills and knowledge, and the entrance requirements for an information technology diploma course
(2008) Baxter, Roger; Lombard, A.; Jordaan, A.
Historically, access to information technology (IT) in South Africa educational institutions has been socially stratified. As a result, many new learners seeking to enter South African tertiary institutions fail to meet the requirements of their preferred course and institution. In 2003, the Department of Information and Corrununications Technology at the Vaal University of Technology (VUT), in conjunction with the National Institute for Information Technology (NIIT), an internationally recognised IT organisation, introduced a short course named the Information Technology Boot Camp (ITBC). This course is now known as the Introduction to Information Technology course (Intro-to-IT). The course is targeted at learners who want to study the IT diploma at the VUT but, who as a result of their Matriculation marks, do not meet the VUT's entrance requirements. The aim of the course is to prepare and qualify these learners for possible acceptance into the IT diploma at the VUT. Although the Intro-to-IT course has impacted positively on the VUT, research has found that learners progressing from the Intro-to-IT course into the IT diploma course experience difficulties in solving programming problems in a logical way. Therefore, the failure rate in Development Software I, a first-semester programming subject, is relatively high. The model described in this study encompasses alterations (implemented and still to be implemented) to the syllabus and content of the Intro-to-IT course, changes to the learning methods and time frames for subjects, and the measurement of these changes in comparison to previous results. The model also includes a software program, which will assess the Intro-to-IT applicants, store results and provide analytical data on all learners' marks and results for the Intro-to-IT short course at the VUT. This model is designed to provide the necessary skills, knowledge and basic logic required to allow successful Intro-to-IT learners the opportunity of success when they enter the VUT's IT diploma stream.
Determination of volatile organic compounds in ambient air by using thermal desorber, sorbent tubes, canister and GC-MS
(2009-06) Mkhwanazi, Sipho Sydney; Naidoo, E. B.; Niemandt, M. J.
The dissertation deals with volatile organic compounds that evaporate from the water-oil separate in the refinery, which causes bad odour around the neighbouring communities, the existence of these compounds are being identified and quantified in different seasons for the year. VOC are emitted whenever wastewater is exposed to the atmosphere. As such, emission points include open drains ditches, manhole sewer outfalls and surface fore bays, separators and treatment ponds. Refinery units such as reactors, fractionators are periodically shutdown and emptied for internal inspection and maintenance. The amount of VOC entering the wastewater is not monitored. The effluent water discharged from the refinery is not checked for the amount ofVOC present. The monitoring of the amount of VOC in wastewater stream may lead to a decrease in the emission. From the quantified results at different season, the summer session has the highest VOC emission due to the heat that causes more vapours. The preparation of a method for determination of VOC's in air presents many difficulties, because of their high volatilities and low concentrations in air. As well, the results of determination are affected by the properties of the sorbent used, mainly its sorption capacity, depending on the properties of the compound under determination. The methods for sampling and analytical procedures for the measurements of volatile organic compounds that are hazardous to air pollution are compendium method T0-14 and sorbent tube method compendium T0-17. Both methods (sorbent tube and canister) differ from each other in their extraction and detection techniques. The well suitable method for the VOC determination is canister method; this method gives more representative sample of the ambient monitoring of 24 hours, where as sorbent tube can do for 2 hours only. The canister method is more advantages due to the sample that will be still remaining for further analyses or re-check. The integrity of API water-oil separator has been improved to cause less evaporation during high temperature season. As the temperature drops from season to season, the VOC also comes down as its being seen in this study that on the winter results that all the VOC were below 90 1-lg/kg.
Characterisation of Amaranthus Tricolor mutant plants with increased drought-tolerance
(Vaal University of Technology, 2010-02) Kgang, Itumeleng Eugenia; Van Emmenis, Lynelle, Dr.; Laloo, Neelan
Amaranthus tricolor (A. tricolor) is a nutritious vegetable crop that is used as a subsistence and cash crop in the rural areas in Africa. Its yield and production is severely limited by abiotic stresses such as drought. Mutation technology, using gamma irradiation, was previously employed as a tool to create genetic variation in order to select for lines with improved drought-tolerance. During irradiation, 160 Gy (Gray) was selected as the optimal dosimetry that allowed subsequent seed germination. The resulting mutant lines were screened over several generations under field and greenhouse conditions and seven promising drought-tolerant lines were selected. Here we report on physiological and morphological studies of two of these Amaranthus mutant lines (#2 and #5) to confirm the enganced drought-tolerance. Plants were grown in the greenhouse in plastic pots containing germination mix with fertiliser. They were exposed to 21 days of well-watered condition, 19 days of drought-stress conditions and 7 days of re-watering. shoot height, leaf area, protein content and relative water content (RWC) of the fresh and dry material were determined colorimetrically under well-watered and drought-stress conditions, while anthocyanin was only measured during well-watered conditions. Shoot height, leaf area, number of leaves per plant and the protein content were significantly reduced under water-stress conditions. Under well-watered condition mutant #5 grew faster with the shoot length significantly higher than mutant #2 and the wild type. Even though drought adversely affected shoot lenght, mutant#5 still performed better than mutant #2 and the wild type under drought-stress conditions. While under both well-watered and drought-stress conditions, the wild type plants had bigger leaf area compared to the two mutant lines. After 16 days of drought-stress conditions, all the leaves of the wild type plants were dried out, as a result no wild type plants recovered after 8 days re-watering. Meanwhile, both mutant #2 and #5 plants recovered significantly after 8 days of re-watering. The wild type was tolerant compared to the two mutant lines. Protein content for mutant #2 plants was higher under both well-watered and drought-stress conditions but was not significantly different from mutant #5 plants compared to the wild type plants after 19 days of drought-stress conditions. Furthermore, genetic diversity was examined in all the Amaranthus lines using random amplified polymorphic DNA (RAPD) analysis. Nineteen arbitrary RAPD markers were used of which two detected polymorphisms (OPA) 07 and OPA 16).
Validity, reliability and fairness of item measurements attained by a comprehensive computer-assisted assessment tool
(2010-11-01T07:40:49Z) van der Merwe, Preller Josefus
The sole purpose of a test is to make a measurement. Assessment is very much a process of measurement, whether the outcome is used for baseline, diagnostic, formative or summative purposes. When measurement is taken, in whatever form, a score is obtained. The score that is obtained forms the important part of assessment, because this score determines the outcome of the assessment, the decisions that are to be made regarding the student’s progress, curriculum changes and the evaluation of a course as a whole. Although a score is obtained from a test, the analysis thereof is frequently much neglected. The use of computers in education is not a new concept. The first computer application goes back a long way when computers were first used to do psychological testing. It then became clear that computers can be applied to more fields in education, especially in the field of testing. In the early days real progress was slow, since computers were expensive and were only used in large companies. However, the scenario has changed with the widespread availability of personal computers that has enabled educators to focus on the appropriate role of computerisation in the development, administration, scoring and interpretation of tests. The main objective of this study is to show the major advantage of using computers as a comprehensive assessment tool and to demonstrate the ability to construct and ‘bank’ test items to subsequently produce a standardised test. An added advantage was the computer’s ability to administer tests to students and manage student progress records. The research findings indicate that a Comprehensive Computer-Assisted Assessment Tool (CCAT) has the potential to contribute to the enhancement of assessment and that it can enable educators to prepare valid, reliable and fair test items which were more difficult and time-consuming without technology.
Reduction of ferric and ferrous compounds in the presence of graphite using mechanical alloying
(Vaal University of Technology, 2011-05) Moloto, Ledwaba Harry; Manzini, Dr. S. S.; Dikio, Dr. E. D.
Many oxidic iron compounds—iron oxides; oxy-hydroxides and hydroxides—not only play an important role in a variety of disciplines but also serve as a model system of reduction and catalytic reactions. There are more than 16 identifiable oxidic iron compounds. The reduction of these compounds has been investigated for centuries. Despite this, the reduction behavior of the oxides is not fully understood as yet. To date the reduction mechanism is still plagued with uncertainties and conflicting theories, partly due to the complex nature of these oxides and intermediates formed during the reduction. Thermodynamically, the reduction of iron oxide occurs in steps. For example, during the reduction of hematite (a-Fe2O3) magnetite (Fe3O4) is first formed followed by non-stoichiometric wüstite (Fe1-yO) and lastly metallic iron (a-Fe). The rate of transformation depends on the reduction conditions. Further, this reduction is accompanied by changes in the crystal structure. The reduction behavior of iron oxides using graphite under ball-milling conditions was investigated using Planetary mono mill (Fritsch Pulverisette 6), Mössbauer Spectroscopy (MS), X-ray Diffraction (XRD), Scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM). It was found that hematite transformed into magnetite, Wüstite and or cementite depending on the milling conditions. The study shows that by increasing the milling time, the rotational speed and / or the ball to powder ratio, the extent of the conversion of hematite to its reduction products increased. Further investigations are required for the elucidation of the reduction mechanism. The reaction og magnetite and graphite at different milling conditions lead to the formation of Fe2+ and Fe3+ species, the former increasing at the expense of Fe3O4. Fe3O4 completely disappeared after a BPR of 50:1 and beyond. The Fe2+ species was confirmed to be due to FeO using XRD analysis. HRSEM images Fe2O3 using scanning electron microscopy prior to and after milling at different times showed significant changes while the milling period was increased, HRSEM images showed that the once well defined hematite particles took ill-defined shapes and also became smaller in size, which was a results of the milling action that induced reaction between the two powders to form magnetite. EDX spectra at different milling times also confirmed formation of magnetite. EDX elemental analysis and quantification confirmed the elemental composition of starting material consisting mainly of iron. Similarly, HRSEM images of Fe3O4 using Scanning electron microscopy (SEM) prior to and after milling at different BPR showed significant changes when the milling period was increased. EDX spectra at different milling times also confirmed formation of partial FeO and EDX elemental analysis and quantification confirmed the elemental composition of starting material consisting mainly of iron than Fe2O3. TEM images of both Fe2O3 and Fe3O4 particles at different milling conditions displayed observable particle damages as a function of milling period.The once well - defined particles (Fe2O3 and Fe3O4 ) successively took ill – defined shapes, possibly accompanied by crystallite size reduction. MAS showed that the reactive milling of α- Fe2O3 and C resulted in reduction to Fe3O4 , FeO and or cementite depending on the milling conditions etc Time, milling speed and BPR variation which influenced the reduction. The study shows that by increasing the milling time, the rotational speed and / or the ball to powder ratio, the extent of the conversion of hematite to its reduction products increased. XRD study investigations even though were unable to detect spm species (Fe2+ and Fe3+ ) which has smaller crystallites below detection limits ,the variation in time showed an increment in the magnetite peaks accompanied by recession of hematite and graphite peaks as the milling time was increased which relates to the MAS observation.XRD also corroborated the data obtained from MAS that showed that the main constituent was magnetite and further evidence in support of the reduction of hematite to magnetite under reactive milling was obtained using XRD . Overall, the work demonstrated selective reduction of Fe2O3 to Fe3O4 and Fe3O4 to FeO by fine tuning the milling conditions. It is envisaged that the reduction of FeO to Fe and possible carburization to FexC could also be achieved.
The effects of biofouling on a reverse osmosis membrane purification system at Sasol, Sasolburg
(Vaal University of Technology, 2011-06) Takaidza, Samkeliso; Van Wyk, C. S.; Stegmann, P., Dr.
Reverse osmosis (RO) membranes are widely used in water purification. The presence of biofilms in water and industrial water purification systems is prevalent. As a result, biofouling which is a biofilm problem causes adverse effects on reverse osmosis process, which include flux decline, shorter membrane lifetime and an increase in energy consumption The effect of biofouling on RO membranes was investigated at a water treatment facility at Sasol, Sasolburg by investigating the quality of water purified by the RO system and the extent of fouling that is attributed to biofouling. Chemical and microbiological data was averaged based on the results obtained from water analysis and samples from a fouled membrane. Bacteriological plate counts ranged between log 1.5 to 4 cfu/ml in water samples and log 3.9 to 4.5 cfu/cm2 on biofilm from the membrane surface. Water analysis indicated a high conductivity of 121 µS/cm in the feed and 81 ppm of the TDS, whereas in the permeate conductivity was found to be around 6 µS/cm and 3.8 ppm of the TDS. This indicated that components present in the feed were retained by the membrane. This was supported by membrane autopsy which showed that the bacteria and elements found in the feedwater were also present on the membrane surface, hence contributing to fouling. An average of 33% of cellular ATP was measured on the biofilm from membrane sample, showing that the fouling bacteria are metabolically active in situ. The results clearly indicated that an important biological activity occurred at the membrane surface.
Separation and recovery of selected transition-metal catalyst systems using membrane processes
(2011-06-06) Xaba, Bongani Michael; Modise, S. J.; Naidoo, E. B.
Membrane separation processes offer a promising alternative to energy-intensive separation processes such as distillation and solvent extraction. NF and RO are among the most investigated membrane processes with a potential use in the chemical industry. Carbon-carbon coupling reactions feature in the top ten most used reactions in the chemical industry. These reactions often use homogeneous palladium, nickel and other precious catalysts which are often difficult to separate from reaction products. This leads to potential product contamination and loss of active catalysts. This not only poses a threat to the environment but is also costly to the chemical industry. The purpose of this study was to investigate the efficiency of the recovery of the metal catalysts by selected membrane processes. Four commercial polymeric NF and RO membranes (NF90, NF270, BW30 and XLE) were selected for the study. Palladium catalysts commonly used in Heck and Suzuki coupling reactions were selected. These are Pd(OAc)2, Pd(OAc)2(PPh3)2, PdCl2 and Pd(PPh3)2Cl2. A range of organic solvents were also selected for the study. All the membranes were characterized for pure water permeability, pure solvent permeability, swelling, surface morphology and chemical structure. The chemical and catalytic properties of the catalysts were determined. Catalytic activity was investigated by performing coupling reactions. These catalysts generally performed well in the Heck coupling reaction with sufficient yields realized. The catalysts showed poor activities in the Suzuki and Sonogashira coupling reactions. These coupling reaction systems were affected by rapid palladium black formation. vi Catalyst retention studies showed the influence of membrane-solute interactions such as steric hindrance and size exclusion. The larger catalyst, Pd(OAc)2(PPh3)2 was rejected better by all the membranes irrespective of the solvent used. The smaller catalyst, Pd(OAc)2 was the most poorly rejected catalyst. This catalyst showed signs of instability in the selected solvents. An interesting finding from this study is that of higher rejections in water compared to other solvents for a particular catalyst. In this regard, the influence of solventsolute effects was evident. Generally, higher rejections were observed in solvents with higher polarity. This has been explained by the concept of solvation. It has been shown that solvents with different polarity solvate solutes differently, therefore leading to a different effective solute diameter in each solvent. Catalyst separation using NF90 membrane was attempted for the Heck coupling reaction system. The reaction-separation procedure was repeated for two filtration cycles with rapid activity decline evident. This was regarded as very poor showing of the catalyst separation efficiency of the membrane. Other authors in similar studies using SRNF membranes have reported reaction-separation processes of up to seven cycles. This observation shows the inferiority of polymeric membranes in organic solvent applications such as catalyst separation.
Identification and quantification of selected pesticides in surface water in Southern Gauteng region
(2011-06-10) Bucibo, Malesole Nontutu Gadihele; Sipamla, A.M.; Sibali, L. L.
The increased production and application of pesticides for agricultural and non-agricultural purposes has caused the pollution of air, soil, ground and surface water. This has a negative impact on the environment as well as human health due to direct exposure or through residues in food and drinking water. The continuous monitoring of pesticides residues in environmental samples has great importance and demands high efficiency, unique selectivity and high sensitivity techniques. Gas chromatography and high performance liquid chromatography have been established for years as the techniques for the analysis of pesticides residues. The dissertation deals with the qualitative and quantitative determination of selected pesticides in the Southern Gauteng region using Liquid- liquid extraction solid-phase extraction, high performance liquid chromatography, gas chromatography equipped with electron capture detector and gas chromatography mass spectrometry. Liquid-liquid extraction and solid-phase extraction using dichloromethane, hexane and ethyl acetate as the extracting solvent were optimized and evaluated for the determination of pesticides in surface water in the Southern Gauteng region. From the developed method the techniques were applied to water samples taken from different rivers selected namely: Zuikerbosch, Rand Water barrage and Kliprivier for sampling. Dichloromethane was used as a solvent in this study since a recovery test was done between dichloromethane, Ethyl acetate and n-hexane. The percentage recovery test for 4,4-DDT, 4,4-DDE, 2,4-DDD and Endosulfan 1 & 2 ranged from 89.9% -97.3% for dichloromethane, 87.3%-96.8% for hexane 88.4%-97.1% for ethyl acetate. The extracts obtained were subjected to column chromatography for clean up. Thereafter 1µl of the cleaned extracts were injected into the Gas chromatography equipped with an electron capture detector. Organochlorines 4,4-DDT and its metabolites, Organophosphate Chlorypyriphos and carbamates were detected using Gas chromatography electron capture, Gas chromatography mass spectrometry and high performance liquid chromatography.
Optimization and verification of changes made to US-EPA 1623 Method to analyse for the presence of Cryptosporidium and Giardia in water
(Vaal University of Technology, 2011-08-03) Khoza, M. N. L. (Mtetwa); Stegmann, P.
Methods for detecting the presence of Cryptosporidium oocysts and Giardia cysts have been developed and continuous improvement is being done to improve the recovery rate of the target protozoa. Rand Water has adopted their method for isolation and detection of Cryptosporidium oocysts and Giardia cysts in water from United State Environmental Protection Agency (US-EPA) Method 1623, 1999. In 2005 changes were made by US-EPA to the Method 1623. A study was done to improve the performance of the Rand Water Method 06 (2007) used for isolation and detection of Cryptosporidium oocysts and Giardia cysts. Three methods namely: Rand Water Method 06 (2007), US-EPA Method 1623 (2005) and Drinking Water Inspectorate standard operating procedures (2003) were compared and key different steps in the methods were identified (wrist action speed, centrifuge speed, immunomagnetic separation procedures and addition of pre-treatment steps). Different experiments were conducted to verify and evaluate the difference between two wrist action shaker speeds, three different centrifuge speeds, two slightly different immunomagnetic separation procedures and when a pre-treatment step was included in the method. Three different types of water matrices (reagent grade water, drinking water and raw water) were used for the experiments and secondary validation. Data obtained from the experiments and secondary validation was statistically analyzed to determine whether there was a significant difference in the recovery of Cryptosporidium oocysts and Giardia cysts. Secondary validation of the Rand Water Method 06 (2007) was performed by implementing the study experiments‟ findings into the method. The results indicated an increase in the recovery rate of Cryptosporidium oocysts and Giardia cysts when data was compared with the previous secondary validation report. The mean recovery of Cryptosporidium oocysts in reagent grade water samples increased from 31% to 55%, drinking water samples increased from 28% to 44% and raw water decreased from 42% to 29%. The mean recovery of Giardia cysts in reagent grade water samples increased from 31% to 41%, drinking water samples increased from 28% to 46% and raw water decreased from 42% to 32%. Furthermore, even though the recovery rate of raw water decreased the use of pre-treatment buffer reduced the number of IMS performed per sample by reducing the pellet size. Enumeration of microscope slides was also easier as there was less background interference. The optimization of the Rand Water Method 06 (2007) was successful as the recovery rate of Cryptosporidium oocysts and Giardia cysts from water increased. All the changes that were verified and that increased the recovery rate were incorporated into the improved Rand Water Method 06.
Effects of oxidation states of Copper (Cu), Nickel (Ni), Palladium (Pd) and Silver (Ag) on rejection by nanofiltration membranes
(2011-08-10) Brooms, Thabo John; Modise, S. J.; Nelana, S. M.
Mining industry produces metals which are economical and serve as high valuable commodities in South Africa. This country is regarded as the world leading producer of precious metals such as platinum group metals (PGMs). Silver (Ag), which is also a precious metal, contribute to the country’s economy wealth due to its significance during industrial applications. Base metals such as copper (Cu) and nickel (Ni), though they are low valued, play a significant role in the republics economic wealth. Mining wastewater contains some of these metals, which end up polluting the environment. A possibility to recover this was investigated using NF membranes. Mine effluent was simulated by using relevant reagents. Characterization of NF90, NF- and NF270 membranes, was done by using scanning electron microscopy (SEM), clean water permeability, single charged salts of NaCl and MgCl2 and binary mixture of NaCl/MgCl2 studies. All the rejection experiments were conducted at pH 2.0 with varying pressure and concentrations. Flux measurements indicated that water permeability through the membranes trend, NF270 > NF90 > NF-. The experiments were performed at pressures of 5 bar, 10 bar, 15 bar and 20 bar. For NF90 membrane, a rejection of Na+ monovalent ion in 20 ppm solution was less than of Mg2+ (divalent) ion. Percentage rejections of 90% (Na+) and 98% (Mg2+) were achieved. NF- had rejection of 83% and 90% for Na+ and Mg2+, respectively. In the case of NF270, the membrane had rejection of 92% (Na+) and 94% (Mg2+), respectively. At 100 ppm, all three membranes showed a decreasing trend in rejection while increasing pressure. For binary-solution mixture, Mg2+ ion still had the highest rejection compared to Na+ ion with about 94% and 85% on NF90 than on NF270 and NF-. The high rejection of divalent ion as compared to monovalent ion for charged solutes was due to solute size and electrostatic interaction between the membrane surface layer and the solute. In the case of transition metal rejection studies, Pd2+ ion had an average of 90%, with Ni2+ ion ≈ 95% and Cu2+ ion ≈ 98% as single salts on NF90 compared to NF270 and NF-. However, as for binary and trinary solution mixture, the competition amongst ions was high, where Pd2+ ion rejection was ≈ 99,0%, while Ni2+ and Cu2+ ions was > 90% on NF90 and NF-. Therefore it was excluded from the tests. For the monovalent metal ions (Ag+ and Cu+), the rejection was > 90% in almost all concentrations mixtures. During membrane fouling evaluation, AgCl salt fouled the most, compared to other metal ions, forming a concentration polarization accumulation on the membrane surface for both 20 and 100 ppm solutions. This situation leads to cake layer formation which causes a flux decline, reduces membrane life time and lowers the rejection performance of NF membranes. The aim of this study was to evaluate the performance of three commercial polymeric membranes (NF90, NF270 and NF-) during rejection of the metal
Is the shelf life of bottled water a cause for concern?
(Vaal University of Technology, 2011-10-27) Liee, Yvone Lieketseng; Ncube, Esper Jacob, Dr.; Van Wyk, Christa
Bottled water like any drinking water used for human consumption should be safe and wholesome to ensure adequate public health protection. This is due to potential health effects of concern such as endocrine disruption, toxicity teratogenicity, mutagenicity and carcinogenicity. Despite the number of regulatory bodies, publications on bottled water and speculations on its public health significance, many questions remain to be answered. One of the questions is whether the shelf life of bottled water is a cause for concern. The aim of the study was to determine the shelf-life of various commercial bottled waters by monitoring the variation in microbiological, chemical and aesthetic qualities of bottled water. A total of five commercial bottled water brands (A, B, C, D, E) each containing bottles from the same batch consisting of spring water, mineral water and bottled tap water were purchased directly after being bottled from different distributors around Gauteng in South Africa. All samples were stored at room temperature with artificial lighting and controlled temperature for a year thus mimicking typical conditions in retail outlets, supermarkets and in homes. Analyses were conducted over a period of 12 months, at monthly intervals. Within days of being purchased, high Heterotrophic plate counts (HPC) bacteria exceeding drinking water alert level >5 000 cfu/ml was common in four bottled water brands. Growth succession occurred during the period of study as various algal species were growing and accumulating on all bottled water tested. Total coliforms (TC), faecal coliforms (FC) and E.coli were not detected in all the bottled water tested. Yeasts and moulds were also not detected in all the bottled water. There were insignificant variations during the period of study for turbidity, pH, TDS, conductivity, and colour. These did not indicate any potential impact on aesthetic quality of bottled water. Two bottled water brands had hardness measures as low as 11mg/ℓ as CaCO3 making the water too soft which has an effect on taste. Radioactive substances, trihalomethanes, heavy metals, pesticides and other chemical contaminants were not found at levels that can be detrimental to human health.
Influence of matrix effect of selected organochlorine pesticide residues in water from the Jukskei River catchment
(Vaal University of Technology, 2011-11) Rimayi, Chengetayi Cornelius; Mtunzi, F., Dr.; Odusanya, A. O. D., Dr.; Van Wyk, C. S.
One of the major problems encountered in qualitative and quantitative determination of residual pesticides by gas chromatography is the matrix effects. Matrix components have a considerable effect on the way analysis is conducted and the quality of results obtained, introducing problems such as inaccurate quantification, low analyte delectability and reporting of false positive or even false negative results. It was aimed to develop and validate a suitable method for counteracting the matrix effects so as to improve the detection and quantification of selected organochlorine pesticide residues from real water samples. The real water samples used were sampled from three points along the Jukskei River catchment area in Gauteng, South Africa for a period of 7 months from January to July 201 0 so as to create a representative sample. An automated solid phase extraction (SPE) method coupled to Gas ChromatographyMass Spectrometry (GC-MS) method for the analysis of 20 selected organochlorine pesticides was developed and validated for the purposes of studying the matrix effects. The analytical method showed a significant degree of validity when tested against parameters such as linearity, repeatability and sensitivity. Endosulphan beta, 4,4' Dichlorodiphenyldichloroethane, and Heptachlor-epoxide had the broadest linear calibration ranges of 1 ppm- 0.0156 ppm. Benzene hexachloride (BHC) delta and Lindane had the lowest statistical limits of detection of 0.018 ppm. Statistical hypothesis testing indicated that there was significant linearity in all selected organochlorine calibration curves. Four different reversed sorbent phases, including LC18, SC18- E and Strata-X (styrene divinyl benzene) were tested for organochlorine retention efficiency. The LC-18 200 mg cartridge proved to be the most robust and effective sorbent phase as it produced better recoveries varying from 90-130% for most analytes. A breakthrough volume of 100 ml for the LC-18 200 mg cartridge was determined using an optimum matrix load curve. It was then concluded that the method developed was suitable for further research towards the influence of the matrix on selective determination of the selected organochlorine pesticides. Four different calibration methods, namely matrix-free external standard, matrixmatched external standard, matrix-free internal standard and matrix-matched internal standard were applied to test the efficiency of computing recoveries. All calibration curves for the 20 organochlorine pesticides showed significant linearity > 0.99 when plotted on both Chemstation and Excel. The calibration methods were tested on three different matrices composed of a high sample matrix (synthetic matrix), a low sample matrix (real sample matrix) and a no sample matrix (ultrapure water). Statistical hypothesis testing led to the decision that there are significant differences between the mean recoveries of the three water sample matrices and also that the differences in the mean recoveries of the three sample matrices are independent of the both the two calibration techniques (internal standard and external standard) and calibration types (matrix-matched and matrix-free) applied. This led to the overall conclusion that the matrix effects have an overwhelming influence on the selective determination of the selected organochlorine pesticides.
Synthesis and characterization of cobalt and copper sulfide nanoparticles with reproducible stoichiometry using sulfur containing single-source precursors
(2012) Sibokoza, Simon Bonginkosi; Moloto, M. J.; Moloto, N.
Complexes of alkyldithiocarbamate and thiuram have been extensively explored for various applications in the medical field. Thiuram and dithiocarbamate ligands were used to prepared complexes of cobalt and copper. The high abundance of sulfur in these ligands has resulted to be the preferred complexes for the synthesis of metal sulfide nanoparticles. All the prepared complexes were characterized using techniques such as IR and 1HNMR spectroscopy, elemental analysis, and thermogravimetric analysis. All the spectra data obtained were consistent with the coordination of the ligands through sulfur atom to the metal ion. The thermogravimetric analysis of all complexes decomposed to form metal sulfide, which really confirmed that all the complexes could be used to metal sulfide nanoparticles. All the prepared complexes were used to synthesize MxSy nanoparticles. The metal sulfide nanoparticles were successful prepared by thermal decomposition of the single-source precursor in hexadecylamine solution. The reaction parameter such as the concentration (1.0, 0.5, 0.25 and 0.125 g), reaction temperature (80, 130, 200, 250 °C) and the time (5, 10, 15, 20, 25 and 30) of the reactionwere varied to see their effect on the preparation of the nanoparticles. The prepared metal sulfide nanoparticles were characterized using techniques such as UV spectroscopy, photoluminescence spectroscopy, X-ray diffraction analysis and transmission electron microscopy. The concentration was found to have a profound effect in size and shape of the prepared nanoparticles. The nanoparticles prepared at various concentrations were dominated by sphere with an average size of 2-30 nm. The XRD pattern confirmed that the composition is not affected by the temperature. Thetemperature has a dramatic effect in size, shape and the stoichiometry of the reaction. This was confirmed by an increase in size as the temperature was increased, with the exception of cobalt sulfide nanoparticles that decrease in size while temperature was increase. The XRD pattern showed different composition as the temperature was varied. Time of the reaction was found to affect the particles size of the nanoparticle. The sizes of the nanoparticles were increase as the time of the reaction was prolonged.
The environmental impact of NATREF refinery storm water on the Taaibosch spruit
(Vaal University of Technology, 2012-01) Ramotsehoa, Motsehoa Cynthia; Van Wyk, C. S.; Stegmann, P., Dr.
NATREF is the only inland refinery in South Africa and as such has unique water disposal challenges since it does not have the advantage of marine outlet like many other refineries. Most of its process streams are treated by the Sasol water treatment facility, leaving the concern of water that collects and drains off during rain fall events from the refinery site. Two sampling points were used during this study. Temperature and pH were measured in situ while bacterial counts and algal bioassays were performed in VUT laboratory. The area experienced a total of 485 mm of rain during the study period with 75 % thereof during spring and summer, there rest in autumn and winter receiving no rain. The average seasonal pH of the samples remained between 8 and 9.3 and this was found to fall within TWQR as well as being within normal range for natural waters. The temperature changes followed a typical summer/winter pattern, with Taaibosch Spruit showing greater variations from 10.95 ˚C in winter to 21.4 ˚C in summer due to its shallow nature. TDS, Nitrates & phosphates were all above the TWQR. Higher HPC & FC counts were observed during spring when rain storms began with Taaibosch Spruit had the higher of the two. As the rainfall continued into summer, the most of the bacterial counts decreased up to the lowest in winter. Higher than expected coliform counts (between 0 and 8 x 104) were observed, indicating a possible source of pollution which has to be studied. Chlorophyll a values ranged from 2.85 μg/L during spring to100 μg/L in winter indicating the potential for stimulation of the algae and possible algal blooms. The algal bioassays showed inhibition potential of the water during spring, summer and autumn with recovery by the winter. This meant that the storm water from NATREF does have a potential to cause chemical & biological pollution of the Taaibosch Spruit although the actual source of storm water pollution has to be properly studied.
Synthesis and characterization of graphene and carbon nanotubes for removal of heavy metals from water
(Vaal University of Technology, 2012-06) Thema, Force Tefo; Moloto, M. J., Prof.; Dikio, E. D., Prof.
The commercial flake graphite was prepared into functionalized graphite oxide (GO) by adopted chemical treatment. After the exfoliation and intercalation of graphite into functionalized graphene oxide that formed stable colloidal dispersion in polar aprotic solvent, the reduction process was undertaken by continuous stirring with hydrazine hydrate in a microwave at 35 oC for two hours. The reduced material was characterized by X-ray diffraction (XRD), attenuated total reflectance (ATR) FT-IR, Ultra-violet visible (UV-vis), atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman microscopy and magnified optical microscopy that confirm the oxidation of graphite and reduction of graphene oxide into graphene sheets. Carbon nanomaterials were synthesized from Co-Sn, Co-Sr and Co-Zn as catalysts supported on Al2O3, CaCO3 and MgO. The as-prepared nanomaterials were characterized by thermogravimetric and derivative thermogravimetric analysis (TGA & DTA), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and the transmission electron microscopy. The intensity ratios (ID/IG) of the D- and G- bands were found to be the same that is averagely at 0.83. The TGA & DTA curves have shown Co-Sn/Al had significant weight loss, Co-Sr/Mg weight loss and decomposition, Co-Sr/Al decomposition and Co-Zn/Mg weight loss. However these weight losses were not significant. The EDS analysis showed all elements which took part in the reaction confirming the success of each synthesis. The SEM images show carbon nanotubes only on samples that have been synthesized on MgO as confirmed by TEM images. Finally the XRD showed some characteristic peaks at desired peaks except that they were other peaks attributed to impurities and armophous carbon. It was also observed that Co-Sn/Ca and Co-Sn/Mg XRD curves showed broad peaks at theta = 24.3o & 42.6o and theta = 23.9o & 43.1o respectively which are lattice structure characteristic peaks.
Investigation of causes of foaming in industrial waste water treatment and effects of substances in industrial waste water treatment
(Vaal University of Technology, 2012-06) Maleka, Mamohau Julia; Sipamla, A. M., Prof.; Mtunzi, F. M., Dr.
The research was aimed to study the causes of excessive foaming in a waste water treatment plant. Although the activated sludge process has been adopted to treat this industrial waste water , lots of problems were experienced by the inhibitory effects of toxic compounds that are found in industrial effluents and the foaming stability that was very high. Industrial waste water treatment using sludge processes was found to be more challenging than the normal municipal waste water treatment although the principle is the same; the foaming tendencies were found to be more in industrial waste water. In this study the composition of influents to the waste water treatment plant and operating parameter’s effects on foaming tendencies were examined. The foaming potential in the plant was found to be chemically related due to high contamination of compounds such as phenols, which played a major role in formation of stable foam. It was recommended that there must be pretreatment of the incoming influents to minimize their impact to waste water treatment.
The construction and evaluation of a novel tubular photobioreactor at a small pilot plant scale
(Vaal University of Technology, 2012-07) Kutama, Makonde; Van Wyk, C.; Stegmann, P., Dr.
The mass production of algae for commercial purposes has predominately been carried out in open ponds systems. However, open ponds systems have a number of disadvantages such as poor light utilization, requirement for large areas of land and high risks of contamination. On the other hand, photobioreactors have attracted much interest because they allow a better control of the cultivation conditions than open systems. With photobioreactors, higher biomass productivities are obtained and contamination can be easily prevented. Photobioreactors can also be engineered to manipulate the light and dark photosynthetic reactions thus enhancing biomass productivity. The main objective of this study was to construct a novel tubular photobioreactor which had the ability to expose the cultured alga to light and dark phases with the aim of optimizing the algal biomass production. A novel tubular photobioreactor with the ability to manipulate the cultured alga’s light and dark photosynthetic reactions was constructed in this study. The alga Spirulina platensis was chosen as the test organism in this novel tubular photobioreactor due to a number of reasons such as its globally socioeconomic importance, its tolerance of higher pH and temperature values which makes it almost impossible to contaminate. The cultivation process of Spirulina in the photobioreactor was investigated through alternating light and dark cycles in an attempt to increase the photosynthetic efficiency of the culture. The effect of different light intensities on the growth of Spirulina in the novel tubular photobioreactor was investigated and it was found that the best light condition that favored higher biomass formation was at 600 μ mol m-2 s-1. Five different light/ dark ratios were evaluated at a light intensity of 600 μ mol m-2 s-1 during a batch mode of operation of the novel tubular photobioreactor. The light/ dark ratio of 1:0.25 was found to be the best ratio because it gave the highest biomass in the shortest period of time when compared to the other ratios used. These results seem to suggest that longer light cycle relative to dark cycle results in higher biomass production. The ratio of 1:0.25 was then used to operate the novel tubular photobioreactor in a continuous mode. A maximum biomass productivity of 25 g/m2/day was achieved which corresponded to a net photosynthetic efficiency of 5.7 %. This result was found to be higher than what most photobioreactors could achieve but it was 2.8 g/m2/day lower than the highest ever reported productivity in a photobioreactor when Spirulina is cultivated. The 2.8 g/m2/day lower was attributed to the different materials used in the construction of these two photobioreactors. The photobioreactor which achieved 27.8 g/m2/day was made up of a clear glass whereas the novel tubular photobioreactor was made up of a PVC tubing. PVC tubes tend to change from clear to a milky colour after a certain period when it is used at higher temperature and pH values hence blocks a certain amount of light. Therefore the main recommendation in this study is to use a PVC tubing with a longer life span when used at a higher temperature and pH values.

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