Performance of magnetic nanocomposites for the removal of some selected contaminants from aqueous solution
- Authors: Ojemaye, Mike Onyewelehi
- Date: 2017
- Subjects: Nanocomposites (Materials)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8746 , vital:33508
- Description: In this thesis, the performances of magnetic nanoparticles based materials were assessed for the removal or reduction of heavy metals in aqueous solutions. The successful synthesis of a novel adsorbent, azomethine functionalized magnetic nanoparticles (MNP-Maph) by covalent bonding between the amine group (-NH2) of amine functionalized magnetic nanoparticles (MNP-NH2) and carboxylic group (-COOH) of 4-{[(E)-phenylmethylidene]amino}benzoic acid (Maph-COOH) was achieved. This adsorbent was examined for the removal of di and trivalent ions (Cu2+, Zn2+, As3+, Pb2+ and Hg2+) from aqueous solutions. Also, magnetic photocatalyst with silica interlayer (NiFe2O4-SiO2-TiO2) was synthesized and employed for the reduction of Cr(VI) in aqueous solution. The photocatalytic reduction efficiency of this material was compared with that of magnetic titanium dioxide (NiFe2O4-TiO2) photocatalyst and titanium dioxide (TiO2) to ascertain the material with the best photocatalytic efficiency and ease of separation. All synthesized materials were characterized by using XRD, FT-IR, TEM, SEM, TGA and VSM before application. For the adsorption processes, the effects of pH, contact time, adsorbent dose and temperature were examined to ascertain the experimental condition necessary for the optimal removal of metal ions from solution. The data obtained from all experiments were fitted into four kinetic models; pseudo-first order, pseudo-second order, elovich and intra particle diffusion models to determine the mechanism involved in the adsorption of these di and trivalent ions while two isotherm models were employed in the adorption processes; these include: Langmuir and Freudlich models. Also, for the photocatalytic experiment, the effects of pH, contact time and photocatalyst dose were investigated to determine the experimental conditions necessary for the optimal reduction of Cr(VI) in aqueous solution. MNP-Maph showed excellent removal capacities of 34.08, 35.83, 50.08, 58.24 and 59.24 mg g-1 for Cu2+, Zn2+, As3+, Pb2+ and Hg2+ respectively compared to data previously reported in literature. This is as a result of the high affinity of azomethine group towards metal ions which tremendously enhanced removal of metal ions by adsorption. The incorporation of azomethine to magnetic nanoparticles improved the affinity towards metal ions removal forming strong electrostatic interaction between the adsorbent active sites and adsorbates. Also, the utilization of NiFe2O4-SiO2-TiO4, NiFe2O4-TiO2 and TiO2 for the reduction of Cr(VI) in aqueous solution showed a good photocatalytic performance with NiFe2O4-SiO2-TiO2 showing to be better in terms of both photocatalytic reduction and magnetic separation. TiO2 was observed to have 96.7percent reduction efficiency within 240 min while NiFe2O4-SiO2-TiO2 has 96.5percent reduction efficiency within 300 min and NiFe2O4-TiO2 gave 60percent reduction efficiency within 300 min of UV irradiation. This magnetic photocatalyst composite (NiFe2O4-SiO2-TiO2) gives the advantage of avoiding the problem of separation often encountered with most photocatalyst materials including TiO2 by allowing separation with the aid of a magnetic field. The adsorption processes were all described by pseudo-second order and Langmuir isotherm models while the photocatalytic process was described by Langmuir-Hinshelwood (L-H) kinetic model. Furthermore, thermodynamic experiment studied for the adsorption processes showed that all metal ion adsorption except Hg2+ by MNP-Maph were endothermic in nature, rapid and spontaneous indicating the feasibility of the sorbent material for the removal of metal ions from aqueous solutions. Also, regenerability study conducted to determine the reusability of sorbent material after seven cycles showed the potential to reuse sorbent material seven times or more. The reusability of the sorbent material was observed to show a percentage of an average of 78percent using 50:50 mixture of 0.1 mol dm-3 HNO3 and HCl for all adsorption processes. For the photocatalytic experiment, regenerability using 0.1 mol dm-3 for 1 h was observed to be very impressive after 3 runs for all synthesized photocatalytic materials. This thereby implies that the removal of metal ions by these materials will not in any way introduce secondary pollutants into the environment. Rather, it will avert the production of secondary pollutants. Also, the use of simple conventional chemicals for the regeneration of synthesized materials showed that regeneration in this study is cost effective as regeneration has been known to cost about three quarter of the total operation and maintenance of an adsorption or photocatalytic process. Application of MNP-Maph to real wastewater sampled from five different wastewater treatment plants in Eastern Cape Province for the removal of Cu2+, Zn2+ and As3+ showed that removal efficiencies of approximately 80 percent were achieved for all three metal ions upon adsorption by MNP-Maph. These therefore show that the introduction of metal loving ligand such as Maph-COOH improved the efficiency of MNP towards the removal of heavy metal ions from aqueous solution. Also, silica positively influenced the performance of magnetic titanium dioxide towards Cr(VI) reduction and separation from aqueous solution. This study therefore showed that these materials should be considered for future applications in the area of water/wastewater decontamination.
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- Date Issued: 2017
An exploration of what Grade 7 Natural Science teachers know, believe and say about biodiversity and the teaching of biodiversity
- Authors: Isaacs, Dorelle
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/1309 , vital:20045
- Description: In the context of the newly implemented Curriculum and Assessment Policy Statements (CAPS) for Natural Science, this study explores what Grade 7 Natural Science teachers know, believe and say about biodiversity and the teaching of biodiversity. Despite its significance to environmental sustainability, biodiversity loss is accelerating in South Africa and internationally, driven by unsustainable economic development models, population growth and associated problems of habitat loss and widespread pollution. Against the backdrop of these challenges, this study shares insights into how teachers’ biodiversity knowledge relates to the CAPS and to international agreements and policies on biodiversity. The study seeks to inform teacher education and support programmes and future curriculum implementation decisions, especially those associated with the Fundisa for Change programme. The study is designed as a qualitative case study inquiry that has used classroom observation, semistructured interviews and document (textbook) analysis to generate data. Theories of teacher cognition (after Shulman, 1987) were used to gain an understanding of teachers’ biodiversity knowledge. Different environmental and biodiversity metaphors and narratives were reviewed to gain an understanding of how teachers represented biodiversity and Kronlid & Öhman’s work on environmental ethics (2012) provided a framework for considering teachers’ values and ethical responses to biodiversity. The study found that the biodiversity knowledge of the teachers in these three case studies was mostly limited to what they access in the curriculum and textbooks. Secondly, there appears to be the assumption that if teachers teach from certain textbooks, they will meet the Specific Aims for Natural Science, as well as implement the process skills which are the ‘new’ knowledge according to the Senior Education Specialist. It was found that teachers’ close adherence to activities prescribed in the textbook seems to limit the depth, scope and criticality of their biodiversity teaching. The study also revealed that all three teachers expressed a pragmatic view of the value of biodiversity. The study recommends that the Natural Science CAPS as well as textbook authors should reflect a more systemic approach to biodiversity knowledge, recognising the interrelations and interdependence of the ecological systems that make up biodiversity – including relationships with humans – and convey a sense of the changeability of biodiversity. Natural Science teachers should be supported in broadening their understanding of biodiversity and biodiversity loss. They should be encouraged and supported to develop or adapt textbook material where necessary and develop learner activities that will encourage their learners to question, deliberate, look for cause and effect, and seek solutions. This may help to realise the final recommendation, that learners and teachers become citizen scientists who will access and contribute to the various biodiversity databases and so join scientists in generating biodiversity knowledge.
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- Date Issued: 2016
A framework to measure supply chain management efficacy in humanitarian supply environments
- Authors: Linford, Pierre
- Date: 2015
- Subjects: Humanitarian intervention , Business logistics
- Language: English
- Type: Thesis , Doctoral , DBA
- Identifier: http://hdl.handle.net/10948/8155 , vital:25131
- Description: Supply chain management in the for-profit commercial environment is a broad, far-reaching field of study, impacting on a society’s standard of living. Commercial supply chain management is the science of balancing customer service levels with least total costs. In other words, the for-profit supply chain management practitioner is concerned with customer service levels, consumer value, shareholder value, total cost optimisation and ultimately maximising long term sustainable return on investment. Commercial supply chain management differs from military supply chain management in that the latter also focuses on service delivery, but the cost is almost irrelevant. In military operations, successful results (winning the battle) far surpass the total cost parameter or the return on investment. One of the major differentiating factors between commercial supply chain management (CSCM) in the for-profit theatre and humanitarian supply chain management (HSCM) in the not-for-profit supply environments hinges on strategic intent and how to measure success. In CSCM, return on investment (ROI) is key and in HSCM, the ability to create impact becomes paramount. Regarding spend, both CSCM and HSCM are concerned with optimising operational spend, optimal utilisation of capital goods and infrastructure as well as minimising the cost of goods, works and services. Commercial supply chain managers want to spend as little as possible on operational expenses similarly to their humanitarian counterparts but humanitarian supply chain managers are also concerned about underspending of donor funded programming. Humanitarian programming often happens under difficult and dangerous circumstances. This requires a special cadre of professionals who are willing to serve the most vulnerable without exploitation and are able to deliver value often with limited or even broken infrastructure, unreliable supply and under insecure conditions. Humanitarian supply chain management leadership requires a DBA thesis balanced approach between long term strategic views whilst managing the short term outcomes. Also, humanitarian leadership needs to balance decision-making between long term strategic interventions and the ability, maturity and cost structures at functional and executional levels. This conundrum is the fundamental difference between commercial supply chain management and humanitarian supply chain management. Once one understands and respects these nuances, one can measure performance and reward appropriate corrective behaviour. Zig Ziglar once said: “If you aim at nothing, you will hit it every time”. The question that has been asked for so long has been “how to measure supply chain management efficacy in humanitarian supply environments?” This study addresses this question of developing a framework to measure supply chain efficacy in humanitarian supply environments with the view to create an enabling environment within which service levels could enhance the impact of donor funding whilst the needs of intended beneficiaries are better served. During field research, ten key focus areas and sixty-five supply chain management elements were identified. These sixty-five elements were tested via two surveys making use of the Delphi technique. Four of the sixty-five SCM elements were eliminated following the second survey due to high disagreement between the respondents, and a further two were eliminated based on expert opinion feedback from the respondents leaving fifty-nine elements being significantly important for inclusion in the framework. Three additional elements were identified by the respondents but not empirically verified and therefore not included in the proposed frameworks but could be included in future research. Fifty-seven of the sixty-five elements can be directly controlled by the SCM function. However, four of these fifty-seven elements were eliminated during the second survey and a further two were eliminated reviewing the feedback from respondents leaving fifty-one elements under the direct control of the SCM function.
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- Date Issued: 2015
Combating corruption while respecting human rights : a critical study of the non-conviction based assets recovery mechanism in Kenya and South Africa
- Authors: Obura, Ken Otieno
- Date: 2014
- Subjects: Human rights -- Kenya , Human rights -- South Africa , Corruption -- Kenya , Corruption -- South Africa , Reparation (Criminal justice) -- Kenya , Reparation (Criminal justice) -- South Africa , Political corruption -- Kenya , Political corruption -- South Africa , Corruption investigation -- Kenya , Corruption investigation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3719 , http://hdl.handle.net/10962/d1013159
- Description: The thesis contributes to the search for sound anti-corruption laws and practices that are effective and fair. It argues for the respect for human rights in the crafting and implementation of anti-corruption laws as a requisite for successful control of corruption. The basis for this argument is threefold: First, human rights provide a framework for checking against abuse of state’s police power, an abuse which if allowed to take root, would make the fight against corruption lose its legitimacy in the eye of the people. Second, human rights ensure that the interest of individuals is catered for in the crafting of anti-corruption laws and practices thereby denying perpetrators of corruption legal excuses that can be exploited to delay or frustrate corruption cases in the courts of law. Third, human rights provide a useful framework for balancing competing interests in the area of corruption control – it enables society to craft measures that fulfils the public interest in the eradication of corruption while concomitantly assuring the competing public interest in the protection of individual members’ liberties – a condition that is necessary if the support of the holders of these competing interests is to be enlisted and fostered in the fight against corruption. The thesis focuses on the study of the non-conviction based assets recovery mechanism, a mechanism that allows the state to apply a procedure lacking in criminal law safeguards to address criminal behaviour. The mechanism is thus beset with avenues for abuse, which if unchecked could have debilitating effects not only to individual liberties but also to the long term legitimacy of the fight against corruption. In this regard, the thesis examines how the human rights framework has been used in Kenya and South Africa to check on the potential dangers of the non-conviction based mechanism and to provide for a proportional balance between the imperative of corruption control and the guarantee against arbitrary deprivation of property. The aim is to unravel the benefits of respecting human rights in the fight against corruption in general and in the non-conviction based assets recovery in particular. Kenya and South Africa are chosen for study because they provide two models of non-conviction based mechanisms with different levels of safeguards, for comparative consideration.
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- Date Issued: 2014
A supplementary coping skills programme for parents of children diagnosed with attention deficit hyperactivity disorder
- Authors: Gomes, Ana Maria
- Date: 2008
- Subjects: Attention-deficit-disordered children -- Family relationships , Children with disabilities -- Education
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9471 , http://hdl.handle.net/10948/686
- Description: Attention Deficit Hyperactivity Disorder (ADHD)-related behaviour difficulties are said to be the cause of much of the disharmony and discord that exists within many families with ADHD-diagnosed children. On the basis of this understanding, a supplementary programme of behaviour modification, referred to as the Coping Skills Programme, was designed and implemented over a designated period of time, as a trial efficiency test, with a view to alleviate some of the family environmental stress caused by the effects of this disorder. There were three main aims to this research project, related to the research questions: Firstly, to establish to what extent this programme helped with the kinds of problems and difficulties being experienced by the parents of ADHD-diagnosed children and by the children themselves; secondly, to make recommendations regarding how to access and use such a programme and learn its skills, and thirdly to determine further ways with which to improve the Coping Skills Programme. The research design was based on Interpretive Theory and was qualitative in nature. An in-depth literature study was undertaken, which together with all the field notes acquired during the course of the study, formed the foundation of the study. A needs analysis was also carried out to ascertain the level and variety of ADHD-related needs that exist within the family unit. This needs analysis took place in the Nelson Mandela Metropole in the Eastern Cape to ascertain the level and variety of ADHD-related needs that exist within the family unit. The sampling selection of participants was both purposeful and dependent on availability, in order obtain as wide a range of information as possible, regarding specific ADHD-related criteria. This data was used as a foundation for the programme’s development. Information was gathered by means of phenomenological interviews, case study analysis, a focus group interview, field notes, observations and an audit trail. Measures were taken to ensure that the study was ethically conducted and trustworthiness maintained. The Coping Skills Programme was implemented with different families with ADHD-diagnosed children, within its designated time, which varied from family to family from between 8 and 10 weeks. Finally, three families were xx selected as case studies to substantiate the findings of this research study. Their selection was based on the range of the children’s age, the variety of their combined needs, the way in which each family dealt with the challenges posed by the programme, the parents’ involvement and the rate of success experienced by each family at the end of the allotted time. At the end of the programme’s implementation period it was found that confusion regarding parental role clarity and the role of the child in the home had a strong bearing on the treatment and management of ADHD-related difficulties. It was also found that the effect of parental unity and/or discord had a direct impact on ADHD-related behaviour. Equally important to the effective management of ADHD-related difficulties were the parental understanding and perceptions regarding their child’s ADHD-related needs and difficulties. The effectiveness of behaviour modification in relation to the level of parental involvement was also salient, as was the use of effective, positive communication to achievement of optimum results. Parental understanding of the role of discipline and how the effective use of this skill benefits the ADHD-diagnosed child became clear, as did the value of consistency in behaviour modification. The conclusion was reached that a programme as flexible as the Coping Skills Programme, when used appropriately and as a supplement to other forms of therapy, may be a significant source of assistance, support, encouragement and empowerment to families with members suffering with ADHD.
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- Date Issued: 2008
A study of piano pedagogy : its history, theory, psychology and practical application
- Authors: Keeves, June Kelk
- Date: 1984
- Subjects: Piano -- Instruction and study Piano -- Methods
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:2662 , http://hdl.handle.net/10962/d1004571
- Description: A discourse concerning the importance followed by a study of piano pedagogy; of piano teaching method, its history and general aspects of piano technique; a fully comprehensive method of piano teaching from the very earliest stages to the advanced; a discussion of various important selected concepts incorporated in the method which require particular emphasis; the application of certain concepts in the various style periods, such as dynamics, tempo, tempo rubato, pedalling, ornamentation, to the teaching of a piece; a discussion of the psychology of piano teaching and practising. All of these various branches of study are imperative in the training of the prospective piano teacher. (Preface)
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- Date Issued: 1984