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The use of carbon nanotubes co-polymerized with calixarenes for the removal of cadmium and organic contaminants from water

- Makayonke, Nozuko Thelma

  • Authors: Makayonke, Nozuko Thelma
  • Date: 2012-05-02
  • Subjects: Water pollution , Nanotubes , Calixarenes , Organic water pollutants , Cadmium toxicology , Carbon , Nanostructured materials , Water purification , Organic compounds removal , Cadmium removal
  • Type: Thesis
  • Identifier: http://ujcontent.uj.ac.za8080/${Handle} , uj:2231 , http://hdl.handle.net/10210/4671
  • Description: M.Sc. , The contamination of water by toxic compounds is one of the most serious environmental problems today. These toxic compounds mostly originate from industrial effluents, agriculture runoff, natural sources (e.g. heavy metals in water from rocks and soil erosion) and human waste. The contamination, which is both “organic” and “inorganic” has an impact on the environment and human health. The demand for water and the pressure to re-use this valuable resource has increased the need for improved techniques and materials to remove pollutants from water. The Nanomaterials Science research group at the University of Johannesburg has focused on developing synthetic polymers that can be employed in water treatment and pollutant monitoring. Recently, cyclodextrins (CD) and carbon nanotubes (CNTs) have been included in polymers for this application. For example, CD-co-hexamethylene-/toluene-diisocyanate polyurethanes and CNT-modified equivalents have been developed and have been successfully applied in removing organic contaminants from water to very low levels.1 Calixarenes are synthetic analogues of cyclodextrins that can be exploited via chemical modification to express a range of properties. In the present study, calixarenes, thiacalixarenes and carbon nanotube-based polymeric materials incorporating these molecules have been synthesised, characterised and tested for removing both organic pollutants (such as p-nitrophenol) and inorganic pollutants (Cd2+, Pb2+) from water. Lead(II) and Cadmium(II) are a threat in South Africa because of their toxicity, and while p-nitrophenol is much less of a problem it represents a useful model organic pollutant. The absorption capacity of the polymers towards heavy metals and organic contaminants was tested by mixing the polymer with synthetic water containing known concentration of the contaminants at about 10 mg/L. Atomic absorption spectrometry (AAS) and ultraviolet-visible spectrometry (UV-vis) were used to determine the levels of heavy metals and organic contaminants, respectively. The target pollutants (Cd2+, 1 see KL Salipira MTech dissertation, University of Johannesburg 2008 Pb2+ and p-nitrophenol) were all successfully removed from water by the various polymers, however the degree of removal and loading capacities of the polymers differed. This information gives some insight into what functional components are needed for making successful adsorbents. It was observed, for example, that ptert- butylcalix[8]arene/hexamethylene diisocyanate (C8A/HMDI) had a higher adsorption capacity towards p-nitrophenol and Pb2+ than towards Cd2+, and also a higher capacity than the corresponding calix[4]arene polymers with smaller calixarene cavities.
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Phosphine derivatized multiwalled carbon nanotubes for the removal of nickel and platinum from solutions

- Muleja, Adolph Anga

  • Authors: Muleja, Adolph Anga
  • Date: 2012-05-02
  • Subjects: Nickel toxicology , Platinum toxicology , Carbon , Nanotubes , Nanostructured materials , Phosphine , Water - Purification - Nickel removal , Water - Purification - Platinum removal
  • Type: Thesis
  • Identifier: uj:2237 , http://hdl.handle.net/10210/4677
  • Description: M.Tech. , Studies on the removal of nickel and platinum are increasing due to the toxicities of these metals. Several methods are currently used to extract these metals however they present limitations. There is hence a need to develop an efficient method for the removal of nickel and platinum from aqueous solution. A study on the use of purified multiwalled carbon nanotubes (purified MWCNTs) and a phosphine derivatized multiwalled carbon nanotubes for the extraction of these metal ions from solution was therefore undertaken. Multiwalled carbon nanotubes (MWCNTs) were produced by nebulised spray pyrolysis, purified by a multi-step technique and functionalized. Phosphine moieties were attached to the bromoarylated- MWCNTs by metallated phosphide route leading to triphenylphoshine linked MWCNTs (Tpp-MWCNTs). As produced, purified and triphenylphosphine linked multiwalled carbon nanotubes were characterized by various techniques, including microscopic and spectroscopic techniques, thermal, elemental and surface analysis. Transmission and scanning electron microscopy used revealed purified MWCNTs had insignificant impurities. X-ray photoelectron spectroscopy (XPS) results showed that triphenylphosphine linked multiwalled carbon nanotubes had 2.6% phosphorus. Zeta potential results demonstrated that purified MWCNTs had positive surface charges at acidic pH. Triphenylphosphine linked multiwalled carbon nanotubes were negatively charged on the surface in acidic media. Batch adsorption experiments were carried out to investigate the removal of nickel and platinum from aqueous solutions. Several parameters which influence the adsorption process were studied, including the effect of pH, the contact time and the effect of initial concentration on adsorption. The adsorption models for the Freundlich and Langmuir isotherms were employed to fit the experimental data. Triphenylphosphine linked MWCNTs removed more nickel (84.68 mg/g) than purified MWCNTs (77.39 mg/g). In contrast, purified MWCNTs removed more platinum (10.5 mg/g) than triphenylphosphine linked MWCNTs (6.01 mg/g). Experimental data for nickel fitted both Freundlich and Langmuir models well whereas only Langmuir model fitted well for platinum. The adsorption of nickel and platinum was indeed found to be pH, time and initial concentration dependent. Metal species (nickel and platinum) in solution had also influenced the uptake of these metals using purified-and Tpp-MWCNTs.
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Economics of carbon sequestration using algae

- Ndleve, Lunghile, Hausberger, Brendon, Jalama, Kalala

Synthesis, characterisation and application of ethylene diamine functionalised carbon nanoparticles for the removal of cadmium (II) and lead (II) from water

- Tshwenya, Luthando

  • Authors: Tshwenya, Luthando
  • Date: 2017
  • Subjects: Water - Purification , Cadmium , Nanostructured materials , Nanotubes , Carbon
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/235777 , uj:24118
  • Description: M.Tech. (Chemistry) , Abstract: This work explores the synthesis, characterisation and application of carbon nanoparticles derived from glucose (GCNPs) and functionalised with ethylene diamine (EDA), towards the removal of Cd(II) and Pb(II) in water samples. Glucose is a simple sugar that is readily available in nature, since it is organic, it can be easily converted to carbon through dehydration. GCNPs were successfully modified to form EDA-GCNPs and characterised by electron microscopy (TEM and SEM), CHNS elemental analysis, Brunauer–Emmett–Teller (BET), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) analysis.Modification of GCNPs with EDA was confirmed from an increase in C-H stretch. Disappearance of carboxyl in the GCNPs and appearance of an amide linkage in the infrared spectra. Based on the particle size results obtained from TEM studies, it was also confirmed that indeed carbon nanoparticles were formed (as the particle sizes were in the nanorange). The adsorption behavior of the two materials for Cd(II) and Pb(II) was investigated by batch adsorption and the effect of several conditions such as contact time, pH, initial metal concentration and competing ions on cadmium and lead uptake were investigated. The adsorption results show that both adsorbents could effectively remove Cd2+ and Pb2+, with lead adsorption being more favoured as compared to that of cadmium. Equilibrium results best fitted the Langmuir model, and the maximum adsorption capacities for Pb(II) were found to be 15.15 and 28.99 mg g-1 for GCNPs and EDA-GCNPs, respectively, whilst Cd(II) adsorption resulted in lower sorption capacities (GCNPs = 10.31 mg g-1 and EDA-GCNPs=18.71 mg g-1). The adsorption processes were found to favour chemisorption, given that the pseudo-second-order kinetic model and Langmuir isotherms best fitted the adsorption results, implying that the functional groups present on the adsorbent surfaces are behind the uptake of these metal ions. The adsorbents showed applicability in real water samples and multi-elemental systems, with competing ions not affecting adsorption processes, moreover, regeneration studies show that both adsorbents are fully recyclable, indicating possible industrial applicability.
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The synthesis and study of branched and filled carbon nanotubes by direct current arc-discharge

- Durbach, Shane Hilton

  • Authors: Durbach, Shane Hilton
  • Date: 2010-04-08T08:42:16Z
  • Subjects: Carbon , Nanostructured materials synthesis , Metal catalysts , Electric discharges through gases
  • Type: Thesis
  • Identifier: uj:6761 , http://hdl.handle.net/10210/3168
  • Description: D.Phil. , The work that is presented in this thesis describes the numerous detailed investigations that were conducted with a custom-made horizontally aligned, water-cooled, gas-filled DC arc-discharge reactor. A focus of the investigations was the establishment of the effects of high purity graphite electrodes in ultra-high purity (UHP) He, H2 or mixtures thereof, in the absence of a metal catalyst on the reaction. These studies showed that higher yields of MWCNTs were formed in reactions between graphite electrodes in H2 than in He. Additionally, a range of gaseous hydrocarbons were formed in H2 that were not formed in He. After the initial parameters were established, investigations examined the effects on the products that were formed by the addition of high purity Cu to graphite. The data from these studies revealed that H2 played a pivotal role in the reactions and that metallic copper nanoparticles were the active catalysts. In particular, they showed that when the Cu/C mole ratio and particle size ranges were fixed (i.e. 0.20 and < 150 μm respectively), then branched CNTs were exclusively found in a collar deposited around the cathode, with bamboo-shaped CNTs formed in the reaction chamber. Characterisation of these products revealed that the Cu nanoparticles were probably molten during the reactions and thus a growth model was proposed in which it was suggested that dehydrogenation reactions of gaseous hydrocarbon species on the surfaces of unsupported molten copper nanoparticles led to the formation of either bamboo-shaped or branched CNTs.
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Synthesis and characterization of copper-containing carbon nanotubes (CNTs) and their use in the removal of pollutants in water

- Nhlabatsi, Zanele Precious

  • Authors: Nhlabatsi, Zanele Precious
  • Date: 2012-06-07
  • Subjects: Copper , Carbon , Nanotubes , Water purification , Escherichia coli removal , Mercury removal
  • Type: Thesis
  • Identifier: uj:8686 , http://hdl.handle.net/10210/5040
  • Description: M.Sc. , Improper disposal of industrial effluents that contain heavy metals such as mercury causes a threat to the environment due to the toxic effects of such matal even at low concentrations. It is also known that sewage waste in water contains bacteria that pose a health hazard to human beings, animals and micro-organisms. One major concern is the transmission of diseases through drinking this water; which destabilizes the water supply. Water for human consumption therefore needs to be of high quality. In this study copper-containing multiwalled carbon nanotubes (Cu/MWCNTs) were investigated for their ability to remove and kill mercury (Hg2+) and Escherichia coli (E. coli), a major species found in the coliform bacteria. These Cu/MWCNTs were synthesized “in situ” by using an electric arc-discharge apparatus and separately via one of two multi-step wet chemical techniques namely; an electroless plating and impregnation method respectively. MWCNTs used for the wet techniques were synthesized by a nebulized spray pyrolysis (NSP) process using ferrocene/toluene under argon flow. These MWCNTs were purified and functionalized to introduce functional groups that made provision for the nucleation of the copper metal on the surface of MWCNTs. Infrared spectroscopy confirmed the successful introduction of COOH and O-H groups on the surface of MWCNTs. Raman spectroscopy confirmed a relative increase in the intensity the ratio of the D-band after functionalization. Deposition of the copper nanoparticles by electroless plating method in different volumes of 100 ml, 80 ml and 60 ml produced copper nanoparticles of varying sizes and distribution on the surface of MWCNTs. SEM images revealed densely and homogeneously distributed small sized copper nanoparticles that followed the trend; 100 ml> 80 ml > 60 ml. The volume proved to be a critical factor of the electroless plating bath with an increase or decrease of the volume affecting the concentration of the Cu2+ ions and HCHO, which also affected the pH of the plating solution.
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The synthesis of phosphorylated multiwalled carbon nanotubes and their use in the removal of Mercury(ll) and Chromium(Vl) ions from aqueous solution

- Velempini, Tarisai Phillipa

Utilization of coal-based sorbents and their fabrication into carbon nanomaterials for the removal of organics from wastewater

- Langwenya, Siphiwe P.

  • Authors: Langwenya, Siphiwe P.
  • Date: 2011-05-16T06:58:03Z
  • Subjects: Sorbents , Nanostructured materials , Carbon , Water purification , Coal absorption and adsorption , Organic compounds removal
  • Type: Thesis
  • Identifier: uj:7068 , http://hdl.handle.net/10210/3630
  • Description: M.Sc. , With increasing industrial activities in South Africa, many of its waters are contaminated with both organic and inorganic pollutants. This is also a worldwide challenge which has resulted in an escalation in research efforts to combat it. Organic pollutants, for example, can be harmful to human health and the environment. Even when present at low concentrations, they tend to bio-accumulate and interact with endocrine systems. Therefore it is necessary that these pollutants are removed from effluents before they are integrated with water systems such as rivers and lakes. In an effort to utilize economic and efficient removal techniques, low cost and locally available materials have been used as potential adsorbents for the removal of these organic pollutants from synthetic wastewater. These coal-based materials were further fabricated into nanoporous sorbents through activation processes to improve their adsorption properties. The project reported in this dissertation was thus undertaken to explore, specifically, the efficacy of coal and coal-based sorbents (acid treated coal, activated carbon and activated fly ash) in their ability to remove phenolic compounds from wastewater.
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Synthesis and properties of carbon nanotubes coated tin dioxide for gas sensing applications

- Motshekga, Sarah Constance

  • Authors: Motshekga, Sarah Constance
  • Date: 2012-07-31
  • Subjects: Carbon , Nanotubes , Nanostructured materials
  • Type: Thesis
  • Identifier: http://ujcontent.uj.ac.za8080/10210/389004 , uj:8885 , http://hdl.handle.net/10210/5356
  • Description: M.Tech. , Among the materials being used for gas sensors, metal oxides are the most important materials because of their potential to detect many gases at low concentrations. Nevertheless, sensors made of metal oxide need to be operated at high temperatures (above 200°C) and have a weak sel ectivity. In order to overcome this difficulty, the materials are being investigated for gas sensing applications. Carbon nanotubes (CNTs) are promising materials with unique properties, such as high electrical conductivity, mechanical strength, nanometer–scale sizes, and high aspect ratio. Their adsorption ability and high surface area make them attractive as gas sensing materials, which have been intensively studied. CNTs can be used solely or combined with metals and oxides materials in order to constitute efficient gas sensors. In the present research, multi–walled CNTs (MWCNTs) were coated with tin dioxide (SnO2) and incorporated into two epoxy resins with widely different mechanical properties in order to study the effect of CNTs on the morphology, mechanical, electrical, and sensing properties of the composites. In the MWCNT/polymer composite study, Epon 828 was used as the polymer matrix and D–2000 (which gives rubbery composites) and T–403 (which gives glassy composites) as the hardeners. Composite were prepared with 0.1 wt.% MWCNTs in an epoxy matrix. Pristine MWCNTs (MWCNTs not treated with any acid and therefore used as received) and SnO2–MWCNTs were used for comparison and a two–step curing procedure was used with initial temperature set at 75°C for 3 hours, followed by additional 3 hours at 125°C. The sample s were characterized for morphology, mechanical, thermo–mechanical and electrical properties using scanning electron microscopy (SEM), an Instron tensile tester, dynamic mechanical analysis (DMA) and Cascade Microtech four–point probe, respectively. In both cases, strong covalent bonds were created as a bridge between the CNTs and matrix, but due to differences in viscosity, the nanotubes dispersion was much better in the rubbery epoxy resin than in the glassy epoxy resin. A 77% increase in tensile modulus was observed in the rubbery system using 0.1 wt.% SnO2–MWCNTs compared to the neat rubbery epoxy. As for the glassy epoxy based composite, only a 3% improvement in tensile modulus could be observed. In addition to the mechanical properties, the presence of CNTs has demonstrated a material with high vi electrical conductivity. But for the surface measurements during the gas sensing analysis, the conductivity was very low for the composites to be used for this application as envisioned. MWCNTs coated with SnO2 nanoparticles used in the present study, were synthesized by a microwave synthesis method. The composite samples were characterized by X–ray diffraction (XRD), Raman spectroscopy, high resolution transmission electron microscopy (HRTEM), scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR) and Brunauer–Emmet–Teller (BET) surface area analysis. These techniques gave evidence for surface and chemical modifications of the synthesized composites. The results showed microwave synthesis to be a very efficient method in producing CNTs that are densely coated and well dispersed with SnO2 nanoparticles in a very short time (total reaction time of 10 minutes). Microwave synthesis is particularly interesting because of the energy used, the higher temperature homogeneity and the shorter reaction times led to nanoparticles with high crystallinity and a narrow particle size distribution. Controlling the morphology by varying synthesis conditions such as temperature, pressure and time is also possible.
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The study of molecule-metal interfaces : structural and electronic properties

- Yagoub, Mubarak Yagoub Adam

Photocatalytic performance of nitrogen-platinum group metal co-doped Tio2 supported on carbon nanotubes for visible-light degradation of organic pollutants in water

- Kuvarega, Alex Tawanda

  • Authors: Kuvarega, Alex Tawanda
  • Date: 2013-07-24
  • Subjects: Water purification , Water purification - Organic compounds removal , Organic water pollutants , Titanium dioxide , Photocatalysis , Nanotubes , Carbon
  • Type: Thesis
  • Identifier: uj:7665 , http://hdl.handle.net/10210/8533
  • Description: D.Phil. (Chemistry) , Elimination of toxic organic compounds from wastewater is currently one of the most important subjects in water-pollution control. Among the many organic pollutants are dyes and emerging pollutants such as natural organic matter (NOM). Dyes such as Eosin Yellow (EY), an anionic xanthene fluorescent dye, can originate from many sources such as textile industrial processes, paper pulp industries and agricultural processes. Most dyes are problematic because they are resistant to conventional chemical or biological water-treatment methods and therefore persist in the environment. NOM consists of a highly variable mixture of products found in water and soils. NOM is formed as a result of the decomposition of plant and animal material and is a precursor to the formation of disinfection by-products (DBP) during water disinfection. These organic compounds cause undesirable colour, taste and odour in water. NOM affects the capacity of other treatment processes to effectively remove organic micro-pollutants or inorganic species that may be present in the water. Its removal also uses up chemicals and energy and so it is expensive to treat. Titanium dioxide (TiO2) has emerged as one of the most fascinating materials in the modern era due to its semiconducting and catalytic properties. TiO2 is a large band-gap semiconductor that exists mainly in the anatase (band gap 3.2 eV) and rutile (band gap 3.0 eV) phases. Its response to UV light has led to increased interest in its application in the photocatalysis research field. It has been investigated extensively for its super hydrophilicity and use in environmental remediation and solar fuel production. In spite of extensive efforts to apply TiO2 for environmental remediation, photocatalytic activity in the visible region has remained quite low hence the ultimate goal of this research was to fabricate highly photoactive catalysts composed of non-metal, platinum-group metal (PGM) co-doped TiO2 and carbon nanotubes (CNTs) and to apply them for water purification using solar radiation...
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Carbon nanotubes and nanospheres: synthesis by nebulised spray pyrolysis and use in catalysis

- Cele, Leskey Mduduzi

  • Authors: Cele, Leskey Mduduzi
  • Date: 2009-05-13T08:47:51Z
  • Subjects: Carbon , Nanotubes , Nanostructured materials , Pyrolysis , Organic compounds synthesis , Palladium catalysts , Hydrogenation , Ethylene
  • Type: Thesis
  • Identifier: uj:8370 , http://hdl.handle.net/10210/2536
  • Description: Ph.D. , This work presents a detailed study of the synthesis of carbon nanotubes and nanospheres by nebulised spray pyrolysis. This method has been used by other workers mainly for preparation of sub-micron particles and the deposition of thin films on various substrates. The effect of various synthesis parameters including the temperature, choice of the carbon source and the metal precursor as well as the carrier gas flow rate on the selectivity of the reaction and the properties of the carbon nanotubes produced was investigated. A major part of this work was devoted to a study of the effects of the addition of small quantities of oxygencontaining compounds (alcohols, esters and aldehydes) to the reaction mixture. The products were analysed using various methods including TEM, SEM, Laser- Raman spectroscopy and HRTEM. Furthermore, the possible use of carbon nanotubes and carbon nanospheres as supports for palladium in the hydrogenation of ethylene was investigated. Nebulised spray pyrolysis proved to be a suitable technique for the synthesis of well graphitized carbon nanotubes and carbon nanospheres with uniform diameters and it was demonstrated that good control of the carbon nanotube properties could be achieved by controlling the synthesis parameters. Better graphitization of the carbon nanotubes was observed at higher temperatures. Ferrocene, iron pentacarbonyl, nickelocene and cobaltocene were successfully used in carbon nanotube synthesis with the last two producing carbon nanotubes with diameters close to those on single-walled carbon nanotubes. Toluene (with and without acetylene as a supplementary carbon source), benzene, mesitylene, xylene and nhexane were successfully used to produce carbon nanotubes with a high degree of alignment while no success was achieved with ethanol. The poor yields obtained with ethanol appear to be a consequence of chemical changes in the ethanol induced by exposure to ultrasound irradiation. On the other hand, low concentrations of methyl acetate and ethyl acetate appear to enhance the production of carbon nanotubes. It was demonstrated that carbon nanotubes and nanospheres are suitable for use as supports for palladium in the hydrogenation of ethylene. Pd particles of uniform size were obtained and the conversion rates were slightly higher when the carbon nanotubes were pre-treated with a mixture of sulphuric acid and nitric acid.
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Slag formation in the reduction zone using coke during high carbon ferromanganese production using South African manganese ores

- Wa Kalenga, Michel Kalenga, Nyembwe, Didier Kasongo

  • Authors: Wa Kalenga, Michel Kalenga , Nyembwe, Didier Kasongo
  • Date: 2019
  • Subjects: Carbon , Slag formation , Reduction zone
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/399423 , uj:33290 , Citation: Wa Kalenga, M.K. & Nyembwe, D.K. 2019. Slag formation in the reduction zone using coke during high carbon ferromanganese production using South African manganese ores.
  • Description: Abstract: It has been observed that during high carbon ferromanganese using South African ores, some practices do not find an easy answer from the theory and vice-versa. It has therefore become important to study under different reducing conditions what paths does the slag go through while forming during reduction in order to better understand its formation while higher manganese oxides are being reduced. The carbon monoxide gas amount and availability in a specific zone albeit its origin is influential and explanatory toward the degree of reduction and the formation of phases. The current investigation focused on the slag formation with the use of coke. The initial basicity of 1.25 was decreased by adding Silica to lower to a value of 1. The flux and the manganese ore were milled together for 15 minutes to homogenise the head sample and ensure same behaviour of the feed throughout. Graphite crucible was used in a alumina tube for experiments. Argon was blown in the furnace from room temperature to 600oC and switched off to allow carbon to start reducing the manganese ore until the set temperature was reached. The sample was kept for two hours at the set temperature, then the furnace was switched off. Argon gas was switched on from 600 oC to room temperature. The temperatures used were 1200 oC and 1350 oC. XRF, XRD and SEMEDS were used for characterization. Phases present in the slag that formed were therefore identified. A comparison was made between the slag quality obtained here and when only carbon monoxide was used for reduction means.
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Synthesis, characterization and properties of novel phosphorylated multiwalled carbon nanotubes/polyvinyl chloride nanocomposites

- Mkhabela, Vuyiswa J.

  • Authors: Mkhabela, Vuyiswa J.
  • Date: 2011-09-13T09:20:26Z
  • Subjects: Nanotubes , Carbon nanotubes , Phosphorylation , Nanocomposites (Materials) , Carbon , Vinyl chloride polymers
  • Type: Thesis
  • Identifier: uj:7198 , http://hdl.handle.net/10210/3833
  • Description: M.Sc. , Carbon nanotubes (CNTs) have been of utmost scientific interest since their discovery in 1991 by a Japanese physicist - Sumio Iijima. This is due to their extraordinary properties which make them one of the most promising options for the design of novel ultrahigh strength polymer nanocomposites. It is believed that the high aspect ratio, mechanical strength, and high electrical and thermal conductivity of these CNTs will enhance the performance of many polymer / CNT nanocomposites and open up new applications. However, poor dispersibility and lack of interfacial adhesion of the CNTs in the polymer matrix have remained a challenge towards fabrication of these nanocomposites. This has been due to the atomically smooth surface of the nanotubes and their intrinsic van der Waals forces which make them chemically inert. This study was aimed at exploring this concept by using novel phosphorylated multiwalled carbon nanotubes (p-MWCNTs) and polyvinyl chloride (PVC) polymer. Phosphorylation of MWCNTs has been successfully achieved in our laboratories, with the p-MWCNTs showing improvement in thermal stability. PVC on the other hand, is the world’s second largest thermoplastic material and has physical properties that are key technical advantages for its use in various and diverse fields such as building and construction, electronics, food packaging and in medical applications. A novel solvent-free method was used to synthesize p-MWCNTs / PVC nanocomposites. MWCNTs were synthesized by nebulized spray pyrolysis, a modification of catalytic vapour deposition and purified by soxhlet extraction using toluene. This method proved to be convenient and economical, producing a high yield of carbon nanotubes. The MWCNTs were phosphorylated with alkylazido phosphonate compounds through a 1,3-dipolar cycloaddition reaction between the phosphonate azides and the C=C bonds of the MWCNTs, with nitrogen loss occurring upon thermolysis. These p-MWCNTs were then melt compounded with PVC to form the p-MWCNTs / PVC nanocomposites. vii The phosphorylation of the MWCNTs and their dispersion in the PVC matrix were characterized by FTIR, SEM, TEM and Raman spectroscopy. Thermal analysis of the nanocomposites by TGA and DSC showed an enhanced thermal stability when comparing the nanocomposites with neat PVC. The modulus of the MWCNTs / PVC nanocomposites increased whilst there was a reduction in their tensile strength, indicating a decrease in polymer toughness.
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What evidence exists relating to effectiveness of ecotechnologies in agriculture for the recovery and reuse of carbon and nutrients in the Baltic and boreo‑temperate regions? a systematic map protocol

- Haddaway, Neal R., Piniewski, Mikołaj, Macura, Biljana

  • Authors: Haddaway, Neal R. , Piniewski, Mikołaj , Macura, Biljana
  • Date: 2019
  • Subjects: Carbon , Circular economy , Eutrophic
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/399965 , uj:33359 , Citation: Haddaway, N.R., Piniewski, M. & Macura, B. 2019. What evidence exists relating to effectiveness of ecotechnologies in agriculture for the recovery and reuse of carbon and nutrients in the Baltic and boreo‑temperate regions? a systematic map protocol. Environ Evid (2019) 8:5 https://doi.org/10.1186/s13750-019-0150-.
  • Description: Abstract: Background: The degradation of the water quality of the Baltic Sea is an ongoing problem, despite investments in measures to reduce external inputs of pollutants and nutrients from both diffuse and point sources. Excessive inputs of nutrients coming from the surrounding land are among the primary causes of the Baltic Sea eutrophication. Diffuse sources, of which most originate from agricultural activities, are two dominant riverine pollution pathways for both nitrogen and phosphorus. Recently, there is growing attention on the reuse of carbon, nitrogen and phosphorus from agricultural waste streams. However, to our knowledge, no comprehensive and systematic assessment of ecotechnologies focusing on recovery or reuse of these substances in the agricultural sector is available. Methods: This map will examine what evidence exists relating to effectiveness of ecotechnologies (here defined as ‘human interventions in social-ecological systems in the form of practices and/or biological, physical, and chemical processes designed to minimise harm to the environment and provide services of value to society’) in agriculture for the reuse of carbon and/or nutrients (nitrogen and phosphorus) in the Baltic Sea region and boreo-temperate systems. We will search for both academic and grey literature: English language searches will be performed in 4 bibliographic databases and search platforms, and Google Scholar, while searches in 38 specialist websites will be performed in English, Finnish, Polish and Swedish. The searches will be restricted to the period 2013 to 2017. Eligibility screening will be conducted at two levels: title and abstract (screened concurrently for efficiency) and full text. Meta-data will be extracted from eligible studies including bibliographic details, study location, ecotechnology name and description, type of outcome (i.e. recovered or reused carbon and/or nutrients), type of ecotechnology in terms of recovery source, and type of reuse (in terms of the end-product). Findings will be presented narratively and in a searchable geographically explicit database, visualised in an evidence atlas (an interactive geographical information system). Knowledge gaps and knowledge clusters in the evidence base will be identified and described.
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Development and fabrication of a wood gasifier to power an internal combustion engine

- Chinguwa, Simon, Nyemba, Wilson R., Jen, Tien-Chien, Boora, Kudzai

  • Authors: Chinguwa, Simon , Nyemba, Wilson R. , Jen, Tien-Chien , Boora, Kudzai
  • Date: 2018
  • Subjects: Carbon , Combustion , Fossil Fuels
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/285610 , uj:30890 , Citation: Chinguwa, S. et al. 2018. Development and fabrication of a wood gasifier to power an internal combustion engine.
  • Description: Abstract: Fossil fuels have been the main source of energy for many years hence the depletion of resource. There is therefore a need for alternative cleaner energy sources of fuel to be explored. The use of these conventional fuels led to land degradation global warming and air pollution. A wood gasifier machine which produces combustible gas from solid fuels like charcoal, wood and agriculture residue was designed. The combustible gas can be used for heating purposes or to produce mechanical or electrical energy. There was a great literature search for the technology currently being used for gasification processes which led to the design and manufacture of the gasifier prototype which was tested and came out successfully. An internal combustion engine was run on the combustible gas. Gasification bi-products that came out were tar and ash which could be used for water proofing and fertilizer respectively. Biofuels are renewable energy sources and are carbon neutral as they do not increase the total amount carbon dioxide in the atmosphere. The test also revealed some shortcomings in the design. The air which was used to allow for combustion to take place was inadequate, hence there is a need for further research.
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A bi-faceted adsorptive performance of TiO₂-Coated carbon for the removal of fluorides in water

- Vilakati, Bongekile R.

Phosphorylation of multiwalled carbon nanotubes

- Ndzimandze, Thembinkosi Mpendulo

  • Authors: Ndzimandze, Thembinkosi Mpendulo
  • Date: 2009-05-07T07:23:39Z
  • Subjects: Phosphorylation , Carbon , Nanotubes , Organic compounds synthesis
  • Type: Thesis
  • Identifier: uj:8362 , http://hdl.handle.net/10210/2503
  • Description: M.Sc. , Carbon nanotubes are among the most exciting new materials being investigated and synthesized, owing to their outstanding mechanical, electronic and optical properties. For more than a decade, the translation of these properties into realistic applications has been hindered by solubility and processing difficulties. Recently the development of efficient methodologies for covalent chemical modification has raised hope for the use of these materials in various fields of application such as biosensors, vaccine and drug delivery systems, medical imaging, biomaterials, water purification, etc... Phosphorylation of functionalized and unfunctionalized multiwalled carbon nanotubes (MWCNTs) is reported in this dissertation. This was achieved by the incorporation of phosphorus moieties on the end and side walls of the MWCNTs. Pristine MWCNTs were functionalized through oxidation by sodium hypochlorite and with a mixture of sulphuric and nitric acids, a diazonium coupling method and by reduction of amide functions on the surface of MWCNTs. Then condensation reactions with alkyl or aryl chlorophosphates were undertaken to obtain compounds 7 to 12. Phosphorylation of pristine MWCNTs was achieved by a 1, 3 dipolar cyclo addition of diphenyl phosphoryl azide. Characterization of the phosphorylated multiwalled carbon nanotubes has been performed by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy X-Ray Dispersive Spectroscopy (EXDS), Thermal Gravimetric Analysis (TGA), Fourier Transform Infrared (FTIR) and Raman Spectroscopy. These techniques together gave evidence for surface, structure and chemical modifications of the synthesized material.
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Cadmium removal from water using nanoparticles embedded on a membrane and detection using anodic stripping voltammetry

- Sam, Simanye

  • Authors: Sam, Simanye
  • Date: 2019
  • Subjects: Cadmium , Carbon , Nanostructured materials , Water - Purification
  • Language: English
  • Type: Masters (Thesis)
  • Identifier: http://hdl.handle.net/10210/401568 , uj:33567
  • Description: Abstract : Water pollution by heavy metals is a serious problem in South Africa due to mining activities, electroplating industries, weathering of minerals and soils and coal combustion. Most river systems have been exposed to heavy metals contamination due to effluent disposal and this directly affects communities that use these sources for domestic purposes. For example, Umtata River which is exposed to Cd(II) is used for various purposes by a large population of the Transkei, most of which is rural - domestic (cooking, drinking and washing), agricultural (that is, livestock watering and irrigation), and recreational purposes (swimming). Water pollution by heavy metals such as, Cd(II) in particular is unavoidable and it causes undesirable health effects, such as hypertension and kidney failure. Thus, it is very important to find new ways to efficiently remove these metals from water. Nanostructured membranes are amongst other water treatment methods that have shown the ability to efficiently remove heavy metals from water. Therefore, this study seeks to provide a facile and effective method to remove heavy metals such as cadmium(II) from synthetic solutions and industrial water effluents. This was achieved by embedding carbon nanodots (CNDs) on a polyethersulfone (PES) membrane as support via phase inversion. The synthesized CNDs and fabricated membranes were characterized using Transmission Electron Microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscope (SEM), Atomic Force Microscope (AFM), contact angle and pure water flux assessment. TEM analysis confirmed that the synthesized CNDs were well dispersed with uniform shape and size (6.7±2.8 nm). Raman analysis illustrated that the CNDs were embedded on the PES and that after blending the PES with CNDs the ID/IG ratio slightly increased after modification of the membranes with CNDs showing that the membranes maintained good structural integrity. The CNDs/PES membranes showed improved hydrophilicity compared to the pristine PES. vi At constant pressure of 300 kPa the flux of pristine PES, 0.01% CNDs/PES, 0.05% CNDs/PES and CNDs/PES was 60.00 L.m-2.h-1, 96.93 L.m-2.h-1, 142.16 L.m-2.h-1 and 196.62 L.m-2.h-1 respectively. The performance of the membrane was optimised using batch adsorption experiments. The analysis revealed that 95.71, 96.32, 97.69 and 99.78% Cd2+ was removed by PES, 0.01% CNDs/PES, 0.05% CNDs/PES and 0.5% CNDs/PES, respectively at optimum conditions: 30 minutes contact time, at pH 5 and 0.5 ppm Cd(II) solution. The membrane, which contained 0.5% CNDs/PES, showed the highest percentage removal. This was due to the –OH and enhanced -COO- on the membrane composite, which could be attributed to the increase in the presence of CNDs within the membrane. , M.Sc. (Chemistry)
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Synthesis and characterization of carbon nanospheres and carbon nanotubes conjugated bisphosphonates as potential drugs for the treatment of secondary bone cancer

- Dlamini, Njabuliso Lucia

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