The use of carbon nanotubes co-polymerized with calixarenes for the removal of cadmium and organic contaminants from water
- 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.
- Full Text:
- 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.
- Full Text:
Granular activated carbon management at a water treatment plant
- Authors: Clements, Michele
- Date: 2009-02-26T12:16:56Z
- Subjects: Water treatment plants , Water purification , Water purification filtration , Activated carbon
- Type: Thesis
- Identifier: uj:8148 , http://hdl.handle.net/10210/2155
- Description: M.Ing. , The Rietvlei Water Treatment Plant was extended with a granular activated carbon (GAC) filtration system after an exhaustive series of tests, which were started in 1994. Upon commissioning towards the middle of 1999, a year of close monitoring followed to measure the GAC performance at full-scale. After verification that the GAC does indeed ensure a high quality product under all conditions, the emphasis shifted to the optimisation of the GAC handling and regeneration system. Frequently moving the entire GAC inventory from the filters to an off-site regeneration plant and back requires significant operational effort and contributes a major part of the total cost of the GAC system. A number of systematic investigations were carried out in response to a number of practical questions that arose at Rietvlei. The first part of the study was directed towards tracking and quantifying the GAC on and off site. The main findings were that 10.0% of the GAC is lost from the filter during backwashing (0.3%) and removal of GAC from the filter for regeneration (9.7%). The sump traps not all this GAC and 2.3% of the total inventory is lost to the river. Inserting a sieve at the outlet of the sump can eliminate this loss. A further 80.3% of the GAC in a filter is removed for regeneration, of which 18.7% is lost during the regeneration process. The minimising off this loss can only be achieved through the optimisation of the regeneration process, which falls within the domain of the regeneration contractor. The second part of the study was directed at the behaviour of the GAC whilst within the filter bed. The porosity and sphericity was determined by laboratory tests and calculations. The porosity was found to be 0.69 for the 12 x 40 size carbon and 0.66 for the 8 x 30 size carbon and the sphericity was found to be 0.67 for the 12 x 40 size carbon and 0.66 for the 8 x 30 size carbon. By using a calibrated bed expansion model, the bed expansion could be calculated at 9°C and 23°C for the two carbons gradings; the maximum temperature range experienced at Rietvlei. The main finding of this part of the study was that the average available freeboard is 650 mm for the 12 x 40 grading and 430 mm for the 8 x 30 grading, and therefore no GAC should wash over the weir at all during backwashing. The third part of the study measured the physical changes of the GAC found at different points in the GAC cycle. The main findings were that the small fraction of GAC washed out of the bed during backwashing and removal has a finer grading, higher apparent density and lower adsorption capacity than the GAC in the filter bed. There seems to be no marked attrition of the carbon or generation of fines during the removal and transport of the GAC to the regeneration plant. After regeneration, there was a 7% decrease in apparent density and a 30% increase in adsorption capacity. The final part of the study correlated the adsorption capacity of the GAC with its time in use as well as UV254 removal. After regeneration, UV254 removal begins at approximately 20% and declines to 14% after 400 days of operation, and to 10% after 600 days. After regeneration, the iodine number begins at approximately 800, declines to 600 after 400 days of operation, and to 500 after 600 days.
- Full Text:
- Authors: Clements, Michele
- Date: 2009-02-26T12:16:56Z
- Subjects: Water treatment plants , Water purification , Water purification filtration , Activated carbon
- Type: Thesis
- Identifier: uj:8148 , http://hdl.handle.net/10210/2155
- Description: M.Ing. , The Rietvlei Water Treatment Plant was extended with a granular activated carbon (GAC) filtration system after an exhaustive series of tests, which were started in 1994. Upon commissioning towards the middle of 1999, a year of close monitoring followed to measure the GAC performance at full-scale. After verification that the GAC does indeed ensure a high quality product under all conditions, the emphasis shifted to the optimisation of the GAC handling and regeneration system. Frequently moving the entire GAC inventory from the filters to an off-site regeneration plant and back requires significant operational effort and contributes a major part of the total cost of the GAC system. A number of systematic investigations were carried out in response to a number of practical questions that arose at Rietvlei. The first part of the study was directed towards tracking and quantifying the GAC on and off site. The main findings were that 10.0% of the GAC is lost from the filter during backwashing (0.3%) and removal of GAC from the filter for regeneration (9.7%). The sump traps not all this GAC and 2.3% of the total inventory is lost to the river. Inserting a sieve at the outlet of the sump can eliminate this loss. A further 80.3% of the GAC in a filter is removed for regeneration, of which 18.7% is lost during the regeneration process. The minimising off this loss can only be achieved through the optimisation of the regeneration process, which falls within the domain of the regeneration contractor. The second part of the study was directed at the behaviour of the GAC whilst within the filter bed. The porosity and sphericity was determined by laboratory tests and calculations. The porosity was found to be 0.69 for the 12 x 40 size carbon and 0.66 for the 8 x 30 size carbon and the sphericity was found to be 0.67 for the 12 x 40 size carbon and 0.66 for the 8 x 30 size carbon. By using a calibrated bed expansion model, the bed expansion could be calculated at 9°C and 23°C for the two carbons gradings; the maximum temperature range experienced at Rietvlei. The main finding of this part of the study was that the average available freeboard is 650 mm for the 12 x 40 grading and 430 mm for the 8 x 30 grading, and therefore no GAC should wash over the weir at all during backwashing. The third part of the study measured the physical changes of the GAC found at different points in the GAC cycle. The main findings were that the small fraction of GAC washed out of the bed during backwashing and removal has a finer grading, higher apparent density and lower adsorption capacity than the GAC in the filter bed. There seems to be no marked attrition of the carbon or generation of fines during the removal and transport of the GAC to the regeneration plant. After regeneration, there was a 7% decrease in apparent density and a 30% increase in adsorption capacity. The final part of the study correlated the adsorption capacity of the GAC with its time in use as well as UV254 removal. After regeneration, UV254 removal begins at approximately 20% and declines to 14% after 400 days of operation, and to 10% after 600 days. After regeneration, the iodine number begins at approximately 800, declines to 600 after 400 days of operation, and to 500 after 600 days.
- Full Text:
Application of metal impregnated carbon nanotubes and cyclodextrin polymers, for the destruction of bacteria in water
- Authors: Lukhele, Lungile Patricia
- Date: 2011-03-02T10:07:45Z
- Subjects: Water purification , Cyclodextrins , Polyurethanes , Nanotubes , Polymerization
- Type: Thesis
- Identifier: uj:7053 , http://hdl.handle.net/10210/3592
- Description: M.Sc. , Safe drinking water is an essential resource for human survival, health, dignity and development. However, this vital resource has become scarce mainly due to population growth, economic activity, climate change and pollution. Treatment of polluted water is expensive and does not always ensure delivery of safe drinking water to humans. Reports on the detection of pollutants such as organics, bacteria, inorganics and the occurrence of toxic disinfection byproducts in treated water in distribution systems have necessitated further research in improving water treatment methods. Metal impregnated carbon nanotube incorporated into cyclodextrin polyurethanes were synthesised by first functionalising carbon nanotubes and then impregnating them with metal nanoparticles. The resultant product was confirmed using Transmission electron microscopy (TEM). The metal nanoparticles were found to have a diameter range of 6 to 35 nm. The metal impregnated carbon nanotubes were then polymerised to produce cyclodextrin polyurethanes. The polymers were characterised using various techniques such as Scanning electron microscopy (SEM), Emission dispersive X-ray spectrometry (EDX) and Brunauer-Emmet-Teller analysis. The metal nanoparticles were found to be part of the polymers through EDX and the polymers’ surface areas were measured to be 0.78 and 0.3383 m2/g for silver and copper polymers, respectively. The synthesised polymers were tested for their efficacy at destroying pathogenic bacteria from water. The polymers were found to inactivate bacteria by up to 4 logs from spiked water samples. These metal impregnated polymers when compared to native carbon nanotubes and cyclodextrin polymers had an enhanced antibacterial property. In environmental samples, metal impregnated polymers destroyed up to 3 logs of bacteria. There was complete removal of bacteria from filtered environmental water samples. Factors affecting the polymers’ efficacy were turbidity, nature of sample and the ratio of bacterial cells removed per gram of polymer.
- Full Text:
- Authors: Lukhele, Lungile Patricia
- Date: 2011-03-02T10:07:45Z
- Subjects: Water purification , Cyclodextrins , Polyurethanes , Nanotubes , Polymerization
- Type: Thesis
- Identifier: uj:7053 , http://hdl.handle.net/10210/3592
- Description: M.Sc. , Safe drinking water is an essential resource for human survival, health, dignity and development. However, this vital resource has become scarce mainly due to population growth, economic activity, climate change and pollution. Treatment of polluted water is expensive and does not always ensure delivery of safe drinking water to humans. Reports on the detection of pollutants such as organics, bacteria, inorganics and the occurrence of toxic disinfection byproducts in treated water in distribution systems have necessitated further research in improving water treatment methods. Metal impregnated carbon nanotube incorporated into cyclodextrin polyurethanes were synthesised by first functionalising carbon nanotubes and then impregnating them with metal nanoparticles. The resultant product was confirmed using Transmission electron microscopy (TEM). The metal nanoparticles were found to have a diameter range of 6 to 35 nm. The metal impregnated carbon nanotubes were then polymerised to produce cyclodextrin polyurethanes. The polymers were characterised using various techniques such as Scanning electron microscopy (SEM), Emission dispersive X-ray spectrometry (EDX) and Brunauer-Emmet-Teller analysis. The metal nanoparticles were found to be part of the polymers through EDX and the polymers’ surface areas were measured to be 0.78 and 0.3383 m2/g for silver and copper polymers, respectively. The synthesised polymers were tested for their efficacy at destroying pathogenic bacteria from water. The polymers were found to inactivate bacteria by up to 4 logs from spiked water samples. These metal impregnated polymers when compared to native carbon nanotubes and cyclodextrin polymers had an enhanced antibacterial property. In environmental samples, metal impregnated polymers destroyed up to 3 logs of bacteria. There was complete removal of bacteria from filtered environmental water samples. Factors affecting the polymers’ efficacy were turbidity, nature of sample and the ratio of bacterial cells removed per gram of polymer.
- Full Text:
Polymerisation of cyclodextrins and multiwalled carbon nanotubes for use in water purification
- Authors: Salipira, Ketulo Lackson
- Date: 2008-06-24T13:18:46Z
- Subjects: Water purification , Organic water pollutants , Nanotubes
- Type: Thesis
- Identifier: uj:9836 , http://hdl.handle.net/10210/723
- Description: B.B. Mamba
- Full Text:
- Authors: Salipira, Ketulo Lackson
- Date: 2008-06-24T13:18:46Z
- Subjects: Water purification , Organic water pollutants , Nanotubes
- Type: Thesis
- Identifier: uj:9836 , http://hdl.handle.net/10210/723
- Description: B.B. Mamba
- Full Text:
Biodegradable polymer composites : synthesis, properties and application in water purification
- Authors: Vilakati, Gcina Doctor
- Date: 2012-05-02
- Subjects: Polymer biodegradation , Water purification , Biodegradation , Composite materials , Polymer deterioration , Heavy metals - Absorption and adsorption
- Type: Thesis
- Identifier: http://ujcontent.uj.ac.za8080/10210/371689 , uj:2232 , http://hdl.handle.net/10210/4672
- Description: M.Sc. , The addition of lignocellulosic fibres to thermoplastic polymers is known to increase the toughness of the polymers but it compromises the tensile strength. On the other hand, inorganic fillers like TiO2 are known to improve the tensile strength of polymers. These plant fibres have been used as adsorbents of metal pollutants in water. Best results were obtained when such materials were ground to fine powder but due to low density, the fibres float and form aggregates in water. Being highly biodegradable in nature makes plant fibres unsuitable for water treatment over lengthy periods of time. They cannot be used as standalone materials. Mixing these adsorbents with polymers, which cannot only act as support for the adsorbents but also disperse the fibres within it thus preventing leaching, is a cause for concern. This study was aimed at fabricating plant fibre-polymer composites that will have improved mechanical and thermal properties. These composites were to be tested for their ability to be used as metal ion adsorbents. The composites were fabricated using a melt-mix compounding method. Two thermoplastic polymers, EVA and PCL were each mixed with either lignin or SCB and TiO2 in different ratios. A rheomex mixer coupled with a single screw extruder which was attached to a sheet die was used to synthesise the composites. TGA and DSC were used for thermal propagation while the mechanical properties were investigated using an instron. Metal ion adsorption measurements were analysed using an atomic absorption spectrometer (AAS). These adsorbents were used to remove Cr(VI), Cr(III) and Pb(II), varying different environmental parameters like pH, concentration, time and adsorbent at constant temperature. The reinforcing effect of both lignin and SCB resulted to poor thermal and mechanical properties. This was shown by a decrease in onset degradation temperature and the tensile and toughness of the composites compared to the neat polymers. The incorporation of TiO2 on SCB-EVA composites, however, improved the mechanical strength and resulted in a thermally stable composite compared to counterpart composites without TiO2. This observation was surpassed at high filler loading as the addition of TiO2 resulted in a decrease of the properties. For the tensile strength, neat EVA recorded 11.35 MPa while 2% TiO2-EVA registered 12.49 MPa for example. For the same composite, the onset degradation temperature for EVA was 353 oC but shifted to 368 oC after the addition of TiO2. At higher filler loading, no effect was observed when adding TiO2.
- Full Text:
- Authors: Vilakati, Gcina Doctor
- Date: 2012-05-02
- Subjects: Polymer biodegradation , Water purification , Biodegradation , Composite materials , Polymer deterioration , Heavy metals - Absorption and adsorption
- Type: Thesis
- Identifier: http://ujcontent.uj.ac.za8080/10210/371689 , uj:2232 , http://hdl.handle.net/10210/4672
- Description: M.Sc. , The addition of lignocellulosic fibres to thermoplastic polymers is known to increase the toughness of the polymers but it compromises the tensile strength. On the other hand, inorganic fillers like TiO2 are known to improve the tensile strength of polymers. These plant fibres have been used as adsorbents of metal pollutants in water. Best results were obtained when such materials were ground to fine powder but due to low density, the fibres float and form aggregates in water. Being highly biodegradable in nature makes plant fibres unsuitable for water treatment over lengthy periods of time. They cannot be used as standalone materials. Mixing these adsorbents with polymers, which cannot only act as support for the adsorbents but also disperse the fibres within it thus preventing leaching, is a cause for concern. This study was aimed at fabricating plant fibre-polymer composites that will have improved mechanical and thermal properties. These composites were to be tested for their ability to be used as metal ion adsorbents. The composites were fabricated using a melt-mix compounding method. Two thermoplastic polymers, EVA and PCL were each mixed with either lignin or SCB and TiO2 in different ratios. A rheomex mixer coupled with a single screw extruder which was attached to a sheet die was used to synthesise the composites. TGA and DSC were used for thermal propagation while the mechanical properties were investigated using an instron. Metal ion adsorption measurements were analysed using an atomic absorption spectrometer (AAS). These adsorbents were used to remove Cr(VI), Cr(III) and Pb(II), varying different environmental parameters like pH, concentration, time and adsorbent at constant temperature. The reinforcing effect of both lignin and SCB resulted to poor thermal and mechanical properties. This was shown by a decrease in onset degradation temperature and the tensile and toughness of the composites compared to the neat polymers. The incorporation of TiO2 on SCB-EVA composites, however, improved the mechanical strength and resulted in a thermally stable composite compared to counterpart composites without TiO2. This observation was surpassed at high filler loading as the addition of TiO2 resulted in a decrease of the properties. For the tensile strength, neat EVA recorded 11.35 MPa while 2% TiO2-EVA registered 12.49 MPa for example. For the same composite, the onset degradation temperature for EVA was 353 oC but shifted to 368 oC after the addition of TiO2. At higher filler loading, no effect was observed when adding TiO2.
- Full Text:
Granular activated carbon performance at three Southern African water treatment plants
- Authors: Olivier, Johan
- Date: 2011-12-07
- Subjects: Water treatment plants , Water purification , Activated carbon
- Type: Thesis
- Identifier: uj:1859 , http://hdl.handle.net/10210/4216
- Description: M. Ing.
- Full Text:
- Authors: Olivier, Johan
- Date: 2011-12-07
- Subjects: Water treatment plants , Water purification , Activated carbon
- Type: Thesis
- Identifier: uj:1859 , http://hdl.handle.net/10210/4216
- Description: M. Ing.
- Full Text:
Development of a calcium carbonate scale formation experimental set-up for the evaluation of physical water treatment devices
- Authors: Da Veiga, Reinaldo
- Date: 2008-11-19T06:20:56Z
- Subjects: Water purification , Fouling , Descaling , Incrustations , Heat exchangers incrustations , Flow meters
- Type: Thesis
- Identifier: uj:14735 , http://hdl.handle.net/10210/1740
- Description: D.Ing.
- Full Text:
- Authors: Da Veiga, Reinaldo
- Date: 2008-11-19T06:20:56Z
- Subjects: Water purification , Fouling , Descaling , Incrustations , Heat exchangers incrustations , Flow meters
- Type: Thesis
- Identifier: uj:14735 , http://hdl.handle.net/10210/1740
- Description: D.Ing.
- Full Text:
Improved access to small community drinking water supply systems and its effect on the probability of bacterial infection posed by water in household drinking water containers
- Authors: Mokoena, Matodzi Michael
- Date: 2010-04-08T08:37:48Z
- Subjects: Water purification , Water quality management
- Type: Thesis
- Identifier: uj:6755 , http://hdl.handle.net/10210/3162
- Description: M. Tech. , The study assessed the risk of infection introduced by containers in which households collect water from different sources. The study area was in rural villages in the Vhembe region of the Limpopo Province. Each village had its own unique water sources consisting mainly of untreated ground waters and untreated surface waters. Randomly selected household members use their containers to collect water from these different sources. Two of the three villages received new small water supply systems within the study period, proving the villagers with water of good health-related microbial quality. The remaining village continued to use contaminated water from their untreated surface water sources. The water supply intervention in two of the three villages provided the opportunity to assess the impact these interventions would have on the risk of infection i.e. whether the risk could be reduced for the villagers no having access to good quality water. A customized quantitative microbial risk assessment was done based on the health-related quality of the water that people ingested before and after the intervention. This assessment was based on exposure of, consequence to and impact on an individual water consumer. Exposure included variables such as daily quantities of unheated drinking water consumed per individual (in litres) available at the point of use (in the dwelling) for ingestion, numbers of diarrhoeagenic E. coli (Dec) per litre in water sampled from containers derived from water samples positive for indicator E. coli and daily doses of DEc per litre ingested by an individual in the target population. Consequence was assessed by calculating the probability of infection per day from diarrhoeagenic E. coli for an individual and from there the annual infection per individual. The impact of the small water supply system was determined by assessing changes in annual individual risk of infection from before to after the interventions per village. In terms of daily water volumes consumed per individual, there were no significant differences in consumption amongst the three villages. At 1.26 ℓcd (at the upper limit of the 95% confidence interval) the consumption was slightly higher than the one litre suggested by WHO 2003. The container water collected from sources before the intervention in the two villages was significantly more contaminated by indicator E. coli (iEc) and diarrhoeagenic E. coli (DEc) than their container waters after the intervention. In terms of impact, the risk of infections was substantially reduced by the interventions. For Village 1 the risk of infection was reduced from 646 infections to 135 infections per 10,000 of the population. If these are converted to 10% as disease manifesting, then there could have been 65 cases of enteric disease attributable to water before the intervention, which was then reduced to 14 cases after the intervention. For Village 2 the population risk was reduced from 110 to 67 cases after the intervention. For Village 3 the population risk remained at 2,778 infections or 278 cases of enteric waterborne disease because of their continued use of untreated water. The study findings indicated that for Village 1, the population risk of infection would be 135 infections per 10,000, for Village 2 it would be 167 and for Village 3 - 234. If the hypothetical conversion rate of one case of enteric waterborne disease for every 10 infections of Howard et al. (2006) is used, then this would mean 14 cases of disease per 10,000 for the population for Village 1, 17 cases for Village 2 and 24 cases for Village 3. Relating this to the WHO (2003) suggestion of one case per 1,000 as an acceptable, it would mean 1.3 cases for Village 1, 1.7 for Village 2 and 2.4 for Village 3. For Village 1 the risk of contracting waterborne enteric disease was close to acceptable, but not at all acceptable for the other two villages, even for Village group 2 after the intervention. The water system in Village 2 failed often during the study which was probably the cause of the persistently higher risk of disease. It can be concluded that providing a well maintained small water supply system reduced the risk to and maintained it at an acceptable level. Table
- Full Text:
- Authors: Mokoena, Matodzi Michael
- Date: 2010-04-08T08:37:48Z
- Subjects: Water purification , Water quality management
- Type: Thesis
- Identifier: uj:6755 , http://hdl.handle.net/10210/3162
- Description: M. Tech. , The study assessed the risk of infection introduced by containers in which households collect water from different sources. The study area was in rural villages in the Vhembe region of the Limpopo Province. Each village had its own unique water sources consisting mainly of untreated ground waters and untreated surface waters. Randomly selected household members use their containers to collect water from these different sources. Two of the three villages received new small water supply systems within the study period, proving the villagers with water of good health-related microbial quality. The remaining village continued to use contaminated water from their untreated surface water sources. The water supply intervention in two of the three villages provided the opportunity to assess the impact these interventions would have on the risk of infection i.e. whether the risk could be reduced for the villagers no having access to good quality water. A customized quantitative microbial risk assessment was done based on the health-related quality of the water that people ingested before and after the intervention. This assessment was based on exposure of, consequence to and impact on an individual water consumer. Exposure included variables such as daily quantities of unheated drinking water consumed per individual (in litres) available at the point of use (in the dwelling) for ingestion, numbers of diarrhoeagenic E. coli (Dec) per litre in water sampled from containers derived from water samples positive for indicator E. coli and daily doses of DEc per litre ingested by an individual in the target population. Consequence was assessed by calculating the probability of infection per day from diarrhoeagenic E. coli for an individual and from there the annual infection per individual. The impact of the small water supply system was determined by assessing changes in annual individual risk of infection from before to after the interventions per village. In terms of daily water volumes consumed per individual, there were no significant differences in consumption amongst the three villages. At 1.26 ℓcd (at the upper limit of the 95% confidence interval) the consumption was slightly higher than the one litre suggested by WHO 2003. The container water collected from sources before the intervention in the two villages was significantly more contaminated by indicator E. coli (iEc) and diarrhoeagenic E. coli (DEc) than their container waters after the intervention. In terms of impact, the risk of infections was substantially reduced by the interventions. For Village 1 the risk of infection was reduced from 646 infections to 135 infections per 10,000 of the population. If these are converted to 10% as disease manifesting, then there could have been 65 cases of enteric disease attributable to water before the intervention, which was then reduced to 14 cases after the intervention. For Village 2 the population risk was reduced from 110 to 67 cases after the intervention. For Village 3 the population risk remained at 2,778 infections or 278 cases of enteric waterborne disease because of their continued use of untreated water. The study findings indicated that for Village 1, the population risk of infection would be 135 infections per 10,000, for Village 2 it would be 167 and for Village 3 - 234. If the hypothetical conversion rate of one case of enteric waterborne disease for every 10 infections of Howard et al. (2006) is used, then this would mean 14 cases of disease per 10,000 for the population for Village 1, 17 cases for Village 2 and 24 cases for Village 3. Relating this to the WHO (2003) suggestion of one case per 1,000 as an acceptable, it would mean 1.3 cases for Village 1, 1.7 for Village 2 and 2.4 for Village 3. For Village 1 the risk of contracting waterborne enteric disease was close to acceptable, but not at all acceptable for the other two villages, even for Village group 2 after the intervention. The water system in Village 2 failed often during the study which was probably the cause of the persistently higher risk of disease. It can be concluded that providing a well maintained small water supply system reduced the risk to and maintained it at an acceptable level. Table
- Full Text:
Polymerization of cyclodextrin-ionic liquid complexes for the removal of organic and inorganic contaminants from water
- Mahlambi, Mphilisi Mciniseli
- Authors: Mahlambi, Mphilisi Mciniseli
- Date: 2009-05-07T07:23:12Z
- Subjects: Polymerization , Water purification , Organic compounds removal , Cyclodextrins
- Type: Thesis
- Identifier: uj:8361 , http://hdl.handle.net/10210/2502
- Description: M.Sc. , The prevalence of toxic contaminants in water remains a huge challenge for water supplying companies and municipalities. Both organic and inorganic contaminants (especially heavy metals) pollutants are often present in water distribution networks. Organic and inorganic pollutants often co-occur in drinking water networks. However, at present there is no water treatment intervention that simultaneously removes organic and inorganic pollutants from water. Additionally, current water treatment technologies fail to remove these contaminants to parts per billion (ppb or µg.L-1) levels. Methods that can simultaneously remove organic and inorganic pollutants to desired levels need to be developed. In our laboratories, both functionalised and unfunctionalised cyclodextrin (CD) polymers have demonstrated the ability to effectively remove organic species from water at low (ppb) concentrations. Cyclodextrins (CDs), which are cyclic oligomers consisting of glucopyranosyl units linked together through α-1,4-glycosidic linkages, behave like molecular hosts. They are capable of interacting with a range of guest molecules within their cylindrical hydrophobic cavities thereby forming the so-called inclusion complexes. Their solubility in water, however, precludes their application in the removal of organic pollutants from water. This limitation is easily dealt with by polymerizing the CDs into water insoluble polymers with suitable bifunctional linkers. On the other hand, ionic liquids (ILs) have been reported to “absorb” heavy metal ions from aqueous media. ILs are low melting point molten salts that are composed of organic cations (e.g. imidazolium and pyridinium ions) and mostly inorganic anions like Cl–, Br–, [PF6]– and [BF4]–. In this study, the two systems were combined by an initial attachment of the imidazolium or pyridinium rings to the cyclodextrin moiety. Polymerisation of the resulting cyclodextrin-ionic liquid (CD-IL) complexes with a suitable linker produced the corresponding water insoluble CD-IL polymers. This dual system has shown excellent capabilities for the removal of model pollutants such as p-nitrophenol (PNP) and 2,4,6-trichlorophenol (TCP) and chromium (Cr6+) from aqueous media. However, the CD-IL polymers showed very little affinity for the absorption of cadmium from water. TGA and DSC studies showed that these polymers are stable over a wide range of temperatures (100-400 C).
- Full Text:
- Authors: Mahlambi, Mphilisi Mciniseli
- Date: 2009-05-07T07:23:12Z
- Subjects: Polymerization , Water purification , Organic compounds removal , Cyclodextrins
- Type: Thesis
- Identifier: uj:8361 , http://hdl.handle.net/10210/2502
- Description: M.Sc. , The prevalence of toxic contaminants in water remains a huge challenge for water supplying companies and municipalities. Both organic and inorganic contaminants (especially heavy metals) pollutants are often present in water distribution networks. Organic and inorganic pollutants often co-occur in drinking water networks. However, at present there is no water treatment intervention that simultaneously removes organic and inorganic pollutants from water. Additionally, current water treatment technologies fail to remove these contaminants to parts per billion (ppb or µg.L-1) levels. Methods that can simultaneously remove organic and inorganic pollutants to desired levels need to be developed. In our laboratories, both functionalised and unfunctionalised cyclodextrin (CD) polymers have demonstrated the ability to effectively remove organic species from water at low (ppb) concentrations. Cyclodextrins (CDs), which are cyclic oligomers consisting of glucopyranosyl units linked together through α-1,4-glycosidic linkages, behave like molecular hosts. They are capable of interacting with a range of guest molecules within their cylindrical hydrophobic cavities thereby forming the so-called inclusion complexes. Their solubility in water, however, precludes their application in the removal of organic pollutants from water. This limitation is easily dealt with by polymerizing the CDs into water insoluble polymers with suitable bifunctional linkers. On the other hand, ionic liquids (ILs) have been reported to “absorb” heavy metal ions from aqueous media. ILs are low melting point molten salts that are composed of organic cations (e.g. imidazolium and pyridinium ions) and mostly inorganic anions like Cl–, Br–, [PF6]– and [BF4]–. In this study, the two systems were combined by an initial attachment of the imidazolium or pyridinium rings to the cyclodextrin moiety. Polymerisation of the resulting cyclodextrin-ionic liquid (CD-IL) complexes with a suitable linker produced the corresponding water insoluble CD-IL polymers. This dual system has shown excellent capabilities for the removal of model pollutants such as p-nitrophenol (PNP) and 2,4,6-trichlorophenol (TCP) and chromium (Cr6+) from aqueous media. However, the CD-IL polymers showed very little affinity for the absorption of cadmium from water. TGA and DSC studies showed that these polymers are stable over a wide range of temperatures (100-400 C).
- Full Text:
Synthesis and characterization of copper-containing carbon nanotubes (CNTs) and their use in the removal of pollutants in water
- 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.
- Full Text:
- 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.
- Full Text:
Utilization of coal-based sorbents and their fabrication into carbon nanomaterials for the removal of organics from wastewater
- 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.
- Full Text:
- 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.
- Full Text:
Natural organic matter (NOM) in South African waters : characterization of NOM, treatability and method development for effective NOM removal from water
- Nkambule, Thabo Innocent Thokozani
- Authors: Nkambule, Thabo Innocent Thokozani
- Date: 2012-11-05
- Subjects: Environmental chemistry , Water purification
- Type: Thesis
- Identifier: uj:7335 , http://hdl.handle.net/10210/8084
- Description: Ph.D. , Natural Organic Matter (NOM) consists of a highly variable mixture of products found in various types of water and soils, formed as a result of decomposition of plant and animal material into water. NOM is a precursor for the formation of disinfection by-products (DBPs) during water disinfection. It causes undesirable colour, taste and odour in water. The reduction of NOM affects the capacity of other treatment processes to remove organic micro-pollutants or inorganic species that may be present in the water. The differing levels and composition of NOM in South African water sources in different regions suggests that a water treatment strategy by a treatment plant should address the issues relating to specific NOM and its treatability. Therefore, in order to reduce NOM from water in a water treatment train, the composition of the NOM in the source water must be taken into account, since its composition at any given time may depend on the local prevailing conditions. The primary objective of this study was therefore to characterize NOM present in South African source waters through extensive sampling of representative water types at identified regions in the country and develop a rapid NOM characterization protocol. Water samples were thus collected from eight different water treatment plants broadly located within the five major source water types of South Africa between the periods of February 2010 to June 2011 in five sampling rounds. The sampling campaigns were planned and timed in order to accommodate the dry and the rainy seasons. The water treatment plants sampled were: Loerie (L) Water Treatment Plant, Midvaal (M) Water Treatment Plant, Olifantsvlei (O) Wastewater Treatment Plant, Plettenberg Bay (P) Water Treatment Plant, Rietvlei (R) Water Treatment Plant, Umzoniana (U) Water Treatment Plant, Vereeniging (V) Water Treatment Plant, and the Wiggins (W) Water Treatment Plant. The L water is from a small impoundment, which is fed from the Kouga Dam. The M water is pumped from the Vaal River.
- Full Text:
- Authors: Nkambule, Thabo Innocent Thokozani
- Date: 2012-11-05
- Subjects: Environmental chemistry , Water purification
- Type: Thesis
- Identifier: uj:7335 , http://hdl.handle.net/10210/8084
- Description: Ph.D. , Natural Organic Matter (NOM) consists of a highly variable mixture of products found in various types of water and soils, formed as a result of decomposition of plant and animal material into water. NOM is a precursor for the formation of disinfection by-products (DBPs) during water disinfection. It causes undesirable colour, taste and odour in water. The reduction of NOM affects the capacity of other treatment processes to remove organic micro-pollutants or inorganic species that may be present in the water. The differing levels and composition of NOM in South African water sources in different regions suggests that a water treatment strategy by a treatment plant should address the issues relating to specific NOM and its treatability. Therefore, in order to reduce NOM from water in a water treatment train, the composition of the NOM in the source water must be taken into account, since its composition at any given time may depend on the local prevailing conditions. The primary objective of this study was therefore to characterize NOM present in South African source waters through extensive sampling of representative water types at identified regions in the country and develop a rapid NOM characterization protocol. Water samples were thus collected from eight different water treatment plants broadly located within the five major source water types of South Africa between the periods of February 2010 to June 2011 in five sampling rounds. The sampling campaigns were planned and timed in order to accommodate the dry and the rainy seasons. The water treatment plants sampled were: Loerie (L) Water Treatment Plant, Midvaal (M) Water Treatment Plant, Olifantsvlei (O) Wastewater Treatment Plant, Plettenberg Bay (P) Water Treatment Plant, Rietvlei (R) Water Treatment Plant, Umzoniana (U) Water Treatment Plant, Vereeniging (V) Water Treatment Plant, and the Wiggins (W) Water Treatment Plant. The L water is from a small impoundment, which is fed from the Kouga Dam. The M water is pumped from the Vaal River.
- Full Text:
Photocatalytic performance of nitrogen-platinum group metal co-doped Tio2 supported on carbon nanotubes for visible-light degradation of organic pollutants in water
- 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...
- Full Text:
- 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...
- Full Text:
Application of cyclodextrin nanoporous polymers in the removal of organic pollutants from water
- Authors: Sithole, Soraya P.
- Date: 2009-04-30T09:21:20Z
- Subjects: Water purification , Cyclodextrins , Polymers , Organic water pollutants
- Type: Thesis
- Identifier: uj:8318 , http://hdl.handle.net/10210/2446
- Description: M.Sc. , The removal of organic pollutants from industrial and municipal water is a great challenge to water providers worldwide. Some of these pollutants are very toxic and pose serious health risks to both humans and animals. Additionally, the presence of organic pollutants in the water often leads to the corrosion of turbines used for power generation at power stations. This obviously makes the power generation process less efficient and thus has cost implications, especially for the end user. Besides the corrosion of turbines, organic water pollutants impact on the cost of generating clean water. To this end, municipalities and industries sourcing water from Rand Water’s treatment plants and Eskom’s power stations (coal-fired power station) may be plagued by high water costs. Geosmin and 2-MIB are detectable by the human nose at concentration levels as low as 10 ng/L. These common water pollutants and are renowned for causing bad taste and odour in drinking water. Although geosmin and 2-MIB do not pose any serious health risks to humans, they impact on the aesthetic and consumer acceptability of drinking water. Currently available technologies such as activated carbon are unable to remove these pollutants to low levels (i.e. ppb levels). In our laboratories, we have found cyclodextrin-based polyurethanes to be effective in the removal of a range of organic pollutants from water to the desired ppb levels. However, these investigations were confined to water samples deliberately spiked with specific pollutants and have not been proven with "real" water samples. We sought to integrate data accumulated in the laboratory by testing and applying these polymers on a larger scale and on real systems. Cyclodextrin (CD) polymers were employed in the removal of 2-MIB, geosmin and other organic pollutants from water. The water was sampled from a coal-fired power station and Zuikerbosch Water Treatment Plant (Rand Water). After using Solid Phase Microextraction (SPME) for the extraction of organic pollutants from the water samples the organic pollutants were identified and quantified using Gas chromatography-mass spectrometry (GC-MS). The new cyclodextrin polymer technology was compared with treatment methods currently applied at both the power station and treatment plant. To determine the environmental friendliness of this technology, polymer degradation studies were also carried out. These entailed performing soil burial tests prior to the characterization of the polymers. Thermogravimetric analysis (TGA), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and Braunner Emmet Tellet (BET) analysis were used for the characterization of the polymers. The techniques were also used to determine if any degradation modifications occurred on the polymeric material. The findings of the study are summarized below: • SPME extraction and GC-MS analyses of geosmin, 2-MIB and other pollutants were successfully accomplished. • The cyclodextrin polymers were effective in the removal of geosmin and 2-MIB (up to 90%) from water sampled at Zuikerbosch water treatment plant. The polymers remained effective (90%) in the absorption of geosmin and 2-MIB even when the water samples were spiked with a competing pollutant (i.e. humic acid). Activated carbon has been noted to have reduced adsorption capacity when humic acid is present in water. • The polymers demonstrated the ability to remove as much as 90% of organic pollutants from raw water compared to the 50% removed by the polyelectrolyte and optimum minimal polyaluminium chloride employed at the coal-fired power station. Analyses of the samples using TOC before and after treatment were accomplished. Reduction in the TOC was noted at the different sampling points after Eskom’s water treatment regime. • Results from the study indicated that the β-CD TDI polymers underwent a greater weight-loss during soil burial when first digested in sulphuric acid (ca. 50% maximum mass loss). On the other hand, β-CD HMDI polymers appeared to be unaffected by predigestion and experienced the same amount mass loss for the digested and undigested polymers (ca. 30% maximum mass loss). SEM studies revealed changes in the surface morphology of the polymers. Moreover, thermogravimetric analysis (TGA) gave an indication of polymer degradation under all soil burial conditions the polymer was subjected to.
- Full Text:
- Authors: Sithole, Soraya P.
- Date: 2009-04-30T09:21:20Z
- Subjects: Water purification , Cyclodextrins , Polymers , Organic water pollutants
- Type: Thesis
- Identifier: uj:8318 , http://hdl.handle.net/10210/2446
- Description: M.Sc. , The removal of organic pollutants from industrial and municipal water is a great challenge to water providers worldwide. Some of these pollutants are very toxic and pose serious health risks to both humans and animals. Additionally, the presence of organic pollutants in the water often leads to the corrosion of turbines used for power generation at power stations. This obviously makes the power generation process less efficient and thus has cost implications, especially for the end user. Besides the corrosion of turbines, organic water pollutants impact on the cost of generating clean water. To this end, municipalities and industries sourcing water from Rand Water’s treatment plants and Eskom’s power stations (coal-fired power station) may be plagued by high water costs. Geosmin and 2-MIB are detectable by the human nose at concentration levels as low as 10 ng/L. These common water pollutants and are renowned for causing bad taste and odour in drinking water. Although geosmin and 2-MIB do not pose any serious health risks to humans, they impact on the aesthetic and consumer acceptability of drinking water. Currently available technologies such as activated carbon are unable to remove these pollutants to low levels (i.e. ppb levels). In our laboratories, we have found cyclodextrin-based polyurethanes to be effective in the removal of a range of organic pollutants from water to the desired ppb levels. However, these investigations were confined to water samples deliberately spiked with specific pollutants and have not been proven with "real" water samples. We sought to integrate data accumulated in the laboratory by testing and applying these polymers on a larger scale and on real systems. Cyclodextrin (CD) polymers were employed in the removal of 2-MIB, geosmin and other organic pollutants from water. The water was sampled from a coal-fired power station and Zuikerbosch Water Treatment Plant (Rand Water). After using Solid Phase Microextraction (SPME) for the extraction of organic pollutants from the water samples the organic pollutants were identified and quantified using Gas chromatography-mass spectrometry (GC-MS). The new cyclodextrin polymer technology was compared with treatment methods currently applied at both the power station and treatment plant. To determine the environmental friendliness of this technology, polymer degradation studies were also carried out. These entailed performing soil burial tests prior to the characterization of the polymers. Thermogravimetric analysis (TGA), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and Braunner Emmet Tellet (BET) analysis were used for the characterization of the polymers. The techniques were also used to determine if any degradation modifications occurred on the polymeric material. The findings of the study are summarized below: • SPME extraction and GC-MS analyses of geosmin, 2-MIB and other pollutants were successfully accomplished. • The cyclodextrin polymers were effective in the removal of geosmin and 2-MIB (up to 90%) from water sampled at Zuikerbosch water treatment plant. The polymers remained effective (90%) in the absorption of geosmin and 2-MIB even when the water samples were spiked with a competing pollutant (i.e. humic acid). Activated carbon has been noted to have reduced adsorption capacity when humic acid is present in water. • The polymers demonstrated the ability to remove as much as 90% of organic pollutants from raw water compared to the 50% removed by the polyelectrolyte and optimum minimal polyaluminium chloride employed at the coal-fired power station. Analyses of the samples using TOC before and after treatment were accomplished. Reduction in the TOC was noted at the different sampling points after Eskom’s water treatment regime. • Results from the study indicated that the β-CD TDI polymers underwent a greater weight-loss during soil burial when first digested in sulphuric acid (ca. 50% maximum mass loss). On the other hand, β-CD HMDI polymers appeared to be unaffected by predigestion and experienced the same amount mass loss for the digested and undigested polymers (ca. 30% maximum mass loss). SEM studies revealed changes in the surface morphology of the polymers. Moreover, thermogravimetric analysis (TGA) gave an indication of polymer degradation under all soil burial conditions the polymer was subjected to.
- Full Text:
Fabrication of polymer composites and their application towards removal of arsenic from water
- Authors: Vunain, Ephraim
- Date: 2012-06-07
- Subjects: Polymer membranes , Polymer composites , Water purification , Arsenic removal
- Type: Thesis
- Identifier: uj:8665 , http://hdl.handle.net/10210/5020
- Description: M.Sc. , Millions of inhabitants worldwide are exposed to arsenic contaminated drinking water as a result of natural and man-made processes. Arsenic especially its inorganic forms, arsenic (III) and arsenic (V) have negative effects on human health especially in developing countries. Therefore fabricating low cost and efficient adsorbents for arsenic (III) removal is of great importance. The aim of this study is to use magnetite (Fe3O4) as filler, incorporated into a polymer blend forming composites as adsorbents for arsenic (III) removal. This work presents the fabrication, characterization and application of Fe3O4-EVA/PCL composites for arsenic (III) removal from water. Fe3O4/Ethylene-vinyl acetate copolymer (EVA)/polyaniline (PANI) and Fe3O4/Ethylene-vinyl acetate copolymer (EVA)/polycaprolactone (PCL) nanocomposites have been successfully synthesized by melt blending technique using a laboratory mixer (Thermo Scientific Haake Rheomex OS). The composites were characterized using scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques. Thermal analysis was done by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and mechanical properties using INSTRON 4443 mechanical Tester. Ability of [EVA (70%) PCL (15%) Fe3O4 (15%)] composites to adsorbed As(III) from water has been investigated through batch experiments. The maximum adsorption was 2.83 mg/g of As(III) ions at 26 ±1°C and pH 8.6. Adsorption data were fitted to Langmuir, Freundlich and Dubinin-Radushkevich isotherms. The process fits well with the Langmuir isotherm. As(III) obeyed pseudo-second order kinetics. The nanocomposites investigated in this study showed good potential for As(III) removal from contaminated water may be due to the dispersion of the magnetite nanoparticles into the polymer blend composites which increases the surface area for the adsorption.
- Full Text:
- Authors: Vunain, Ephraim
- Date: 2012-06-07
- Subjects: Polymer membranes , Polymer composites , Water purification , Arsenic removal
- Type: Thesis
- Identifier: uj:8665 , http://hdl.handle.net/10210/5020
- Description: M.Sc. , Millions of inhabitants worldwide are exposed to arsenic contaminated drinking water as a result of natural and man-made processes. Arsenic especially its inorganic forms, arsenic (III) and arsenic (V) have negative effects on human health especially in developing countries. Therefore fabricating low cost and efficient adsorbents for arsenic (III) removal is of great importance. The aim of this study is to use magnetite (Fe3O4) as filler, incorporated into a polymer blend forming composites as adsorbents for arsenic (III) removal. This work presents the fabrication, characterization and application of Fe3O4-EVA/PCL composites for arsenic (III) removal from water. Fe3O4/Ethylene-vinyl acetate copolymer (EVA)/polyaniline (PANI) and Fe3O4/Ethylene-vinyl acetate copolymer (EVA)/polycaprolactone (PCL) nanocomposites have been successfully synthesized by melt blending technique using a laboratory mixer (Thermo Scientific Haake Rheomex OS). The composites were characterized using scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques. Thermal analysis was done by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and mechanical properties using INSTRON 4443 mechanical Tester. Ability of [EVA (70%) PCL (15%) Fe3O4 (15%)] composites to adsorbed As(III) from water has been investigated through batch experiments. The maximum adsorption was 2.83 mg/g of As(III) ions at 26 ±1°C and pH 8.6. Adsorption data were fitted to Langmuir, Freundlich and Dubinin-Radushkevich isotherms. The process fits well with the Langmuir isotherm. As(III) obeyed pseudo-second order kinetics. The nanocomposites investigated in this study showed good potential for As(III) removal from contaminated water may be due to the dispersion of the magnetite nanoparticles into the polymer blend composites which increases the surface area for the adsorption.
- Full Text:
The polymerization of cyclodextrins modified with silicon (Si) and titanium (Ti) based compounds for the removal and degradation of organic contaminants in water
- Authors: Mbuli, Bhekani Sydney
- Date: 2010-04-08T08:32:55Z
- Subjects: Organic water pollutants , Water purification , Cyclodextrins synthesis
- Type: Thesis
- Identifier: uj:6749 , http://hdl.handle.net/10210/3157
- Description: M.Sc. , Water that is free from toxic organic pollutants is essential to human health and the environment at large. Organic contaminants may affect the endocrine system of animals and humans, even when present in very low concentrations (i.e. levels ppb). Current technologies fail to remove these organic compounds efficiently from water at ppb levels. So, the development of new technologies that are capable of removing and degrading organic pollutants from water is crucial. Hence, recently in our laboratories cyclodextrin (CD) polymers have demonstrated that they are capable of removing organic pollutants from water at ppb levels. The research has also demonstrated that both functionalized and unfunctionalized CD polymers can remove organic species to as low as parts per billion (ppb) from water. In this project, Si and Ti based compounds which have been reported to degrade organic compounds through photocatalysis in an aqueous media were incorporated. Firstly, attempts were made to attach the silicon (Si) and titanium (Ti) pendent chains onto the CD moiety to form silicon-based cyclodextrin (Si-CD) and titanium based cyclodextrin (Ti-CD) precursors. The Si-CD precursor was synthesized by attaching the 3-(triethoxysilyl)propyl isocyanate onto the native b-CD moiety. The synthesis of the Si-CD precursor was successful and high yields (80%) of the product were obtained. A hydrolysis of this Si-CD precursor in an inert atmosphere led to the formation of silanol. This was followed by curing the silanol in air, after adding TiO2 nanoparticles, and the Ti-CD precursor was formed. The polymerization of Si-CD with suitable bifunctional linkers was a success and water-insoluble polymers were produced. An attempt to polymerize the Ti-CD precursor failed, because the precursor was decomposed. The Si-CD polymers were tested for their capabilities to encapsulate and destroy organic pollutants from water. 1H NMR, FT-IR and EDX spectroscopic techniques were used to prove the formation of the Si-CD and Ti-CD precursors and their corresponding polymers. The Si-CD polymers showed capabilities of being able to remove organic pollutants (33-55%) from water. Unfortunately, the removal is slightly less efficient than the corresponding native CD polymers. However, their efficiency in removing organic pollutants improved when exposed to light. Moreover, the polymers formed display good thermal stabilities, since they decompose at about 300- 400°C. This is observed from the thermograms obtain ed from DSC and TGA. Their morphological studies showed that most of the Si-CD polymers formed were crystalline. This was observed from the SEM images obtained. Based on the information provided by the FT-IR spectroscopy, the synthesis of the Ti-CD precursor was success. However, the challenge was the fact that it decomposed after a while. Hence, it was difficult polymerize it into a water insoluble polymer. The explanation of this phenomenon is not yet established.
- Full Text:
- Authors: Mbuli, Bhekani Sydney
- Date: 2010-04-08T08:32:55Z
- Subjects: Organic water pollutants , Water purification , Cyclodextrins synthesis
- Type: Thesis
- Identifier: uj:6749 , http://hdl.handle.net/10210/3157
- Description: M.Sc. , Water that is free from toxic organic pollutants is essential to human health and the environment at large. Organic contaminants may affect the endocrine system of animals and humans, even when present in very low concentrations (i.e. levels ppb). Current technologies fail to remove these organic compounds efficiently from water at ppb levels. So, the development of new technologies that are capable of removing and degrading organic pollutants from water is crucial. Hence, recently in our laboratories cyclodextrin (CD) polymers have demonstrated that they are capable of removing organic pollutants from water at ppb levels. The research has also demonstrated that both functionalized and unfunctionalized CD polymers can remove organic species to as low as parts per billion (ppb) from water. In this project, Si and Ti based compounds which have been reported to degrade organic compounds through photocatalysis in an aqueous media were incorporated. Firstly, attempts were made to attach the silicon (Si) and titanium (Ti) pendent chains onto the CD moiety to form silicon-based cyclodextrin (Si-CD) and titanium based cyclodextrin (Ti-CD) precursors. The Si-CD precursor was synthesized by attaching the 3-(triethoxysilyl)propyl isocyanate onto the native b-CD moiety. The synthesis of the Si-CD precursor was successful and high yields (80%) of the product were obtained. A hydrolysis of this Si-CD precursor in an inert atmosphere led to the formation of silanol. This was followed by curing the silanol in air, after adding TiO2 nanoparticles, and the Ti-CD precursor was formed. The polymerization of Si-CD with suitable bifunctional linkers was a success and water-insoluble polymers were produced. An attempt to polymerize the Ti-CD precursor failed, because the precursor was decomposed. The Si-CD polymers were tested for their capabilities to encapsulate and destroy organic pollutants from water. 1H NMR, FT-IR and EDX spectroscopic techniques were used to prove the formation of the Si-CD and Ti-CD precursors and their corresponding polymers. The Si-CD polymers showed capabilities of being able to remove organic pollutants (33-55%) from water. Unfortunately, the removal is slightly less efficient than the corresponding native CD polymers. However, their efficiency in removing organic pollutants improved when exposed to light. Moreover, the polymers formed display good thermal stabilities, since they decompose at about 300- 400°C. This is observed from the thermograms obtain ed from DSC and TGA. Their morphological studies showed that most of the Si-CD polymers formed were crystalline. This was observed from the SEM images obtained. Based on the information provided by the FT-IR spectroscopy, the synthesis of the Ti-CD precursor was success. However, the challenge was the fact that it decomposed after a while. Hence, it was difficult polymerize it into a water insoluble polymer. The explanation of this phenomenon is not yet established.
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Synthesis, characterization and application of nanoporous cyclodextrin polymers
- Authors: Bambo, Mokae Fanuel
- Date: 2008-08-15T07:43:33Z
- Subjects: Water purification , Organic compounds removal
- Type: Thesis
- Identifier: http://ujcontent.uj.ac.za8080/10210/375904 , uj:7749 , http://hdl.handle.net/10210/863
- Description: The presence of organic contaminants in water has caused great concern over their potential adverse health impact on humans and animals. Organic contaminants found in water are both naturally occurring and synthetic. Various chemical and physical water treatment processes are being used to remove organic contaminants. Conventional water treatment methods include the utilization of activated carbon for the removal of organic contaminants. It is generally conceded that activated carbon owes its adsorptive properties primarily to its large surface area, as well as to its pore size. Although activated carbon is nonselective against most of the water contaminants, it does not remove the concentration of organic contaminants to acceptable levels i.e. ppb. Moreover, activated carbon also absorbs moisture from the air and as a result loses its absorptive effectiveness. For this reason attention has been being given to alternative methods for water treatment especially for the removal of organic pollutants. In this study, cyclodextrin polymers that were water insoluble were synthesized and tested for their ability to remove organic species in water. Cyclodextrins (CDs) and their corresponding derivatives have been used in a wide range of applications including pharmaceutical and pesticide removal and catalysis. Cyclodextrins are cyclic oligosaccharides derived from enzyme degradation of starch. They are known as molecular hosts capable of including of forming inclusion complexes, with a degree of selectivity, with a range of guest molecules via a noncovalent interaction in their hydrophobic cavities. Although the interaction between cyclodextrin and an organic molecule is the basis for absorption or separation of various organic agents, the solubility of cyclodextrin in water and organic solvents impose limitations to the application of cyclodextrins in water treatment. Therefore, polymerizing a cyclodextrin monomer with an excess of a bifunctional linker produces an insoluble polymer which can form inclusion complexes with guest molecules. In this project, the synthesis of a number of cyclodextrin polymers was performed by reacting cyclodextrin with bifunctional linkers. , Dr. B. B. Mamba Dr. R. W. M. Krause Dr. T. J. Malefetse
- Full Text:
- Authors: Bambo, Mokae Fanuel
- Date: 2008-08-15T07:43:33Z
- Subjects: Water purification , Organic compounds removal
- Type: Thesis
- Identifier: http://ujcontent.uj.ac.za8080/10210/375904 , uj:7749 , http://hdl.handle.net/10210/863
- Description: The presence of organic contaminants in water has caused great concern over their potential adverse health impact on humans and animals. Organic contaminants found in water are both naturally occurring and synthetic. Various chemical and physical water treatment processes are being used to remove organic contaminants. Conventional water treatment methods include the utilization of activated carbon for the removal of organic contaminants. It is generally conceded that activated carbon owes its adsorptive properties primarily to its large surface area, as well as to its pore size. Although activated carbon is nonselective against most of the water contaminants, it does not remove the concentration of organic contaminants to acceptable levels i.e. ppb. Moreover, activated carbon also absorbs moisture from the air and as a result loses its absorptive effectiveness. For this reason attention has been being given to alternative methods for water treatment especially for the removal of organic pollutants. In this study, cyclodextrin polymers that were water insoluble were synthesized and tested for their ability to remove organic species in water. Cyclodextrins (CDs) and their corresponding derivatives have been used in a wide range of applications including pharmaceutical and pesticide removal and catalysis. Cyclodextrins are cyclic oligosaccharides derived from enzyme degradation of starch. They are known as molecular hosts capable of including of forming inclusion complexes, with a degree of selectivity, with a range of guest molecules via a noncovalent interaction in their hydrophobic cavities. Although the interaction between cyclodextrin and an organic molecule is the basis for absorption or separation of various organic agents, the solubility of cyclodextrin in water and organic solvents impose limitations to the application of cyclodextrins in water treatment. Therefore, polymerizing a cyclodextrin monomer with an excess of a bifunctional linker produces an insoluble polymer which can form inclusion complexes with guest molecules. In this project, the synthesis of a number of cyclodextrin polymers was performed by reacting cyclodextrin with bifunctional linkers. , Dr. B. B. Mamba Dr. R. W. M. Krause Dr. T. J. Malefetse
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An analytical approach to the characterization and removal of natural organic matter from water using ozone and cyclodextrin polyurethanes
- Authors: Nkambule, Thabo Innocent
- Date: 2010-04-08T08:44:47Z
- Subjects: Water purification , Organic water pollutants , Ion exchange resins , Cyclodextrins , Polyurethanes
- Type: Thesis
- Identifier: uj:6765 , http://hdl.handle.net/10210/3171
- Description: M.Sc. , The prevalence of natural organic matter (NOM) in water remains a huge challenge for water treatment companies and municipalities. NOM, however, is not a stand-alone problem as it affects water quality in many ways. NOM is largely responsible for the formation of disinfection by-products (DBPs) via its interaction with disinfectants during water disinfection. It is implicated for the undesirable colour, taste and odour of water and NOM even inhibits precipitation precursors which form the backbone of drinking water treatment. There is therefore no question that NOM, which is either a precursor to or direct cause of the problems highlighted above, should be considered as one of the critical design parameters to be considered for drinking water treatment. In our laboratories, research that involves the use of cyclodextrin (CD) polyurethanes for the removal of organic pollutants from water has been extensively investigated, and the CD polyurethanes have demonstrated the ability to effectively remove the organic species from water at low (ppb) concentrations. CDs, which are cyclic oligomers consisting of glucopyranosyl units linked together through α-1,4 glycosidic linkages, behave like molecular hosts. They are capable of forming inclusion complexes with guest molecules and hence can be utilised for the removal of organic contaminants from water. Their solubility in water, however, limits their application in the removal of organic contaminants from water. This limitation is easily resolved by polymerising the CDs into water-insoluble polymers with bifunctional linkers such as hexamethylene diisocyanate (HMDI). In this study, CD polyurethanes and ion exchange resins were used for the removal of NOM and possibly its DBPs from water. This study first investigated the local NOM source to establish its type and character, hence the study involved the characterization of the bulk water samples and fractionating the NOM using ion exchange resins for further characterization. The water samples were found to consist mainly of humic substances in the form of hydrophobic NOM, with the hydrophilic basic (HpiB) fraction being the most abundant NOM fraction in all samples. Trihalomethanes (THMs) were used as a representative of DBPs in this vii study. THMs formation studies of the individual NOM fractions indicated that all six NOM fractions were found to form THMs but in varying proportions. The HpiB fraction was found to be the most reactive precursor fraction for THMs formation. The ozonation process was also independently evaluated for its ability to remove the NOM fractions from water. Ozonation was found not to be very effective at NOM removal since it only resulted in a 12% overall decrease of the NOM in the water samples. The CD polyurethanes, when used alone, were also not very effective at removing the NOM fractions from water (maximum of 33% NOM removal). On the other hand, the combination method (i.e. the use of CD polyurethanes and ozonation for NOM removal) resulted in a good capability of the CD polyurethanes at decreasing some NOM fractions in water as evidenced by a 73% and 88% decrease of the HpiB and hydrophilic acid (HpiA) fractions, respectively. The 73% reduction of the HpiB fraction demonstrates a great success of the combination approach employed herein, as this study reports this fraction as the most reactive precursor fraction for THM formation.
- Full Text:
- Authors: Nkambule, Thabo Innocent
- Date: 2010-04-08T08:44:47Z
- Subjects: Water purification , Organic water pollutants , Ion exchange resins , Cyclodextrins , Polyurethanes
- Type: Thesis
- Identifier: uj:6765 , http://hdl.handle.net/10210/3171
- Description: M.Sc. , The prevalence of natural organic matter (NOM) in water remains a huge challenge for water treatment companies and municipalities. NOM, however, is not a stand-alone problem as it affects water quality in many ways. NOM is largely responsible for the formation of disinfection by-products (DBPs) via its interaction with disinfectants during water disinfection. It is implicated for the undesirable colour, taste and odour of water and NOM even inhibits precipitation precursors which form the backbone of drinking water treatment. There is therefore no question that NOM, which is either a precursor to or direct cause of the problems highlighted above, should be considered as one of the critical design parameters to be considered for drinking water treatment. In our laboratories, research that involves the use of cyclodextrin (CD) polyurethanes for the removal of organic pollutants from water has been extensively investigated, and the CD polyurethanes have demonstrated the ability to effectively remove the organic species from water at low (ppb) concentrations. CDs, which are cyclic oligomers consisting of glucopyranosyl units linked together through α-1,4 glycosidic linkages, behave like molecular hosts. They are capable of forming inclusion complexes with guest molecules and hence can be utilised for the removal of organic contaminants from water. Their solubility in water, however, limits their application in the removal of organic contaminants from water. This limitation is easily resolved by polymerising the CDs into water-insoluble polymers with bifunctional linkers such as hexamethylene diisocyanate (HMDI). In this study, CD polyurethanes and ion exchange resins were used for the removal of NOM and possibly its DBPs from water. This study first investigated the local NOM source to establish its type and character, hence the study involved the characterization of the bulk water samples and fractionating the NOM using ion exchange resins for further characterization. The water samples were found to consist mainly of humic substances in the form of hydrophobic NOM, with the hydrophilic basic (HpiB) fraction being the most abundant NOM fraction in all samples. Trihalomethanes (THMs) were used as a representative of DBPs in this vii study. THMs formation studies of the individual NOM fractions indicated that all six NOM fractions were found to form THMs but in varying proportions. The HpiB fraction was found to be the most reactive precursor fraction for THMs formation. The ozonation process was also independently evaluated for its ability to remove the NOM fractions from water. Ozonation was found not to be very effective at NOM removal since it only resulted in a 12% overall decrease of the NOM in the water samples. The CD polyurethanes, when used alone, were also not very effective at removing the NOM fractions from water (maximum of 33% NOM removal). On the other hand, the combination method (i.e. the use of CD polyurethanes and ozonation for NOM removal) resulted in a good capability of the CD polyurethanes at decreasing some NOM fractions in water as evidenced by a 73% and 88% decrease of the HpiB and hydrophilic acid (HpiA) fractions, respectively. The 73% reduction of the HpiB fraction demonstrates a great success of the combination approach employed herein, as this study reports this fraction as the most reactive precursor fraction for THM formation.
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Natural clinoptilolite for the removal of cobalt and copper from aqueous solutions
- Authors: Nyembe, Dumsile W.
- Date: 2011-03-02T10:12:23Z
- Subjects: Water purification , Copper absorption and adsorption , Cobalt , Clinoptilolite
- Type: Thesis
- Identifier: uj:7054 , http://hdl.handle.net/10210/3593
- Description: M.Sc. , The metallurgical industrial losses of base metals with waste solutions are an environmental threat to water sources, hence these metal ions must be removed prior to discharge into receiving bodies. In this study, Southern African clinoptilolite’s capability as an ion-exchanger with respect to Cu2+ and Co2+ was investigated in order to consider its application in metal cation removal from aqueous solutions. The clinoptilolite was characterised with X-ray powder diffraction (XRD), X-ray fluorescence (XRF), FTIR, thermogravimetric analyser (TGA) and SEM-EDS. The clinoptilolite was found to be a thermally stable alumino-silicate with calcite, dolomite and quartz as the main minerals. Investigations of Co2+ and Cu2+ uptake were first performed on non-mixed solutions of these cations. It was found that Cu2+ was removed faster than Co2+ with removal efficiencies of 79% and 63% respectively. The column method was used in the cation-exchange processes with synthetic solutions of 0.0020 M, 0.0698 M and 0.2000 M of Co2+ and Cu2+ concentrations which were measured using atomic absorption spectroscopy (AAS). The effects of Co2+ and Cu2+ ions on one another’s removal efficiency were investigated on Co/Cu mixed synthetic solutions by varying their concentration ratios in solution. The Cu2+ was generally found to be removed at lower rates than the Co2+. Investigations on added impurities in the form of Si4+ and Fe2+ in the mixed Co/Cu synthetic solutions were carried out to determine their effect on the removal efficiencies of the targeted metals. It was found that both Si4+ and Fe2+ greatly reduced the removal efficiency of Cu2+, especially with increased amounts of Si4+ in the Co/Cu solution.
- Full Text:
- Authors: Nyembe, Dumsile W.
- Date: 2011-03-02T10:12:23Z
- Subjects: Water purification , Copper absorption and adsorption , Cobalt , Clinoptilolite
- Type: Thesis
- Identifier: uj:7054 , http://hdl.handle.net/10210/3593
- Description: M.Sc. , The metallurgical industrial losses of base metals with waste solutions are an environmental threat to water sources, hence these metal ions must be removed prior to discharge into receiving bodies. In this study, Southern African clinoptilolite’s capability as an ion-exchanger with respect to Cu2+ and Co2+ was investigated in order to consider its application in metal cation removal from aqueous solutions. The clinoptilolite was characterised with X-ray powder diffraction (XRD), X-ray fluorescence (XRF), FTIR, thermogravimetric analyser (TGA) and SEM-EDS. The clinoptilolite was found to be a thermally stable alumino-silicate with calcite, dolomite and quartz as the main minerals. Investigations of Co2+ and Cu2+ uptake were first performed on non-mixed solutions of these cations. It was found that Cu2+ was removed faster than Co2+ with removal efficiencies of 79% and 63% respectively. The column method was used in the cation-exchange processes with synthetic solutions of 0.0020 M, 0.0698 M and 0.2000 M of Co2+ and Cu2+ concentrations which were measured using atomic absorption spectroscopy (AAS). The effects of Co2+ and Cu2+ ions on one another’s removal efficiency were investigated on Co/Cu mixed synthetic solutions by varying their concentration ratios in solution. The Cu2+ was generally found to be removed at lower rates than the Co2+. Investigations on added impurities in the form of Si4+ and Fe2+ in the mixed Co/Cu synthetic solutions were carried out to determine their effect on the removal efficiencies of the targeted metals. It was found that both Si4+ and Fe2+ greatly reduced the removal efficiency of Cu2+, especially with increased amounts of Si4+ in the Co/Cu solution.
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Optimisation of culture methods for the selective isolation of diarrhoeagenic Escherichia coli from water
- Authors: Heine, Lee
- Date: 2008-08-13T12:19:12Z
- Subjects: Escherichia coli , Water quality biological assessment , Water purification
- Type: Thesis
- Identifier: uj:7661 , http://hdl.handle.net/10210/852
- Description: Diarrhoea caused by strains of Escherichia coli is recognised as a significant cause of morbidity and mortality world-wide. Efficient isolation of these bacteria from water is necessary for effective management of available water sources and for the control and prevention of waterborne disease. Methods that are currently available do not allow for the efficient isolation of the diarrhoeagenic E. coli. Therefore, the aims of the current study were: to determine the efficacy of Chromocult® Coliformen Agar for identification of diarrhoeagenic E. coli; correlate virulence gene carriage with biochemical profiles of diarrhoeagenic E. coli; and develop an enrichment method for the selective isolation of diarrhoeagenic E. coli. Chromocult® Coliformen Agar proved unreliable for identifying diarrhoeagenic E. coli – 30% of strains would have been incorrectly identified using this medium. The carriage of pathotype-specific virulence genes by enteroaggregative E. coli strains was associated with the production of ornithine decarboxylase and the fermentation of sucrose. The enrichment procedure detailed in this study was an improvement upon an existing method. In addition, the improved method proved effective for the isolation of five diarrhoeagenic E. coli pathotypes. In contrast, the original procedure was only shown to be effective when isolating enterohaemorrhagic E. coli. The improved method was applied on environmental water and two samples yielded colonies positive for genes carried by enteropathogenic E. coli and enterotoxigenic E. coli, respectively. As confirmation of these results PCR products were sequenced and corresponded to published sequences of the virulence genes. , Ms. P.S. Kay Dr. T. G. Barnard Prof. P. Jagals
- Full Text:
- Authors: Heine, Lee
- Date: 2008-08-13T12:19:12Z
- Subjects: Escherichia coli , Water quality biological assessment , Water purification
- Type: Thesis
- Identifier: uj:7661 , http://hdl.handle.net/10210/852
- Description: Diarrhoea caused by strains of Escherichia coli is recognised as a significant cause of morbidity and mortality world-wide. Efficient isolation of these bacteria from water is necessary for effective management of available water sources and for the control and prevention of waterborne disease. Methods that are currently available do not allow for the efficient isolation of the diarrhoeagenic E. coli. Therefore, the aims of the current study were: to determine the efficacy of Chromocult® Coliformen Agar for identification of diarrhoeagenic E. coli; correlate virulence gene carriage with biochemical profiles of diarrhoeagenic E. coli; and develop an enrichment method for the selective isolation of diarrhoeagenic E. coli. Chromocult® Coliformen Agar proved unreliable for identifying diarrhoeagenic E. coli – 30% of strains would have been incorrectly identified using this medium. The carriage of pathotype-specific virulence genes by enteroaggregative E. coli strains was associated with the production of ornithine decarboxylase and the fermentation of sucrose. The enrichment procedure detailed in this study was an improvement upon an existing method. In addition, the improved method proved effective for the isolation of five diarrhoeagenic E. coli pathotypes. In contrast, the original procedure was only shown to be effective when isolating enterohaemorrhagic E. coli. The improved method was applied on environmental water and two samples yielded colonies positive for genes carried by enteropathogenic E. coli and enterotoxigenic E. coli, respectively. As confirmation of these results PCR products were sequenced and corresponded to published sequences of the virulence genes. , Ms. P.S. Kay Dr. T. G. Barnard Prof. P. Jagals
- Full Text: