Conducting nanocomposites for the removal of heavy metals from wastewater
- Authors: Kera, Nazia Hassan
- Date: 2018
- Subjects: Heavy metals - Absorption and adsorption , Sewage - Purification - Heavy metals removal , Water - Purification , Nanocomposites (Materials) , Water chemistry
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://ujcontent.uj.ac.za8080/10210/366683 , http://hdl.handle.net/10210/278783 , uj:29923
- Description: Ph.D. (Chemistry) , Abstract: Hexavalent chromium, Cr(VI), is a toxic heavy metal pollutant that occurs in wastewater produced from mining and industrial activities such as leather tanning, chrome plating, wood preservation and alloy manufacture. Cr(VI) released into the environment is of concern due to its high mobility in water and soil and harmful effects on human health. The treatment of wastewater is necessary to prevent Cr(VI) contamination of water bodies in the environment. Conducting polymers, such as polypyrrole (PPy) and polyaniline (PANI), have the potential to be used as adsorbents for Cr(VI) in wastewater due to their abundant nitrogen-containing functional groups, anion-exchange sites and capacity to reduce Cr(VI) to the significantly less toxic, trivalent chromium, Cr(III). However, conducting polymers have shown low adsorption capacities for Cr(VI) due to agglomeration of particles and are also difficult to separate from treated water. The focus of this study was on the development of conducting polymer composites for the treatment of wastewater containing Cr(VI). In particular, the aim of the research carried out was the modification of conducting polymers to obtain adsorbents with high adsorption capacities for Cr(VI) that are well-suited towards water treatment applications. Three novel conducting polymer composites were prepared in this study, namely, polypyrrole/2,5-diaminobenzenesulfonic acid (PPy/DABSA) composite, polypyrrole-polyaniline/iron oxide (PPy-PANI/Fe3O4) magnetic nanocomposite and polypyrrole-m-phenylenediamine (PPy-mPD) polymer for the desired application of removing Cr(VI) from industrial wastewater. The composites were synthesized easily and effectively by in situ chemical oxidative polymerization and their physicochemical properties characterized using various techniques including attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area analysis. Batch studies were carried out to investigate the effect of parameters such as initial solution pH, adsorbent dose, initial Cr(VI) concentration, temperature and co-existing ions in solution on Cr(VI) removal by the different composites...
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- Authors: Kera, Nazia Hassan
- Date: 2018
- Subjects: Heavy metals - Absorption and adsorption , Sewage - Purification - Heavy metals removal , Water - Purification , Nanocomposites (Materials) , Water chemistry
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://ujcontent.uj.ac.za8080/10210/366683 , http://hdl.handle.net/10210/278783 , uj:29923
- Description: Ph.D. (Chemistry) , Abstract: Hexavalent chromium, Cr(VI), is a toxic heavy metal pollutant that occurs in wastewater produced from mining and industrial activities such as leather tanning, chrome plating, wood preservation and alloy manufacture. Cr(VI) released into the environment is of concern due to its high mobility in water and soil and harmful effects on human health. The treatment of wastewater is necessary to prevent Cr(VI) contamination of water bodies in the environment. Conducting polymers, such as polypyrrole (PPy) and polyaniline (PANI), have the potential to be used as adsorbents for Cr(VI) in wastewater due to their abundant nitrogen-containing functional groups, anion-exchange sites and capacity to reduce Cr(VI) to the significantly less toxic, trivalent chromium, Cr(III). However, conducting polymers have shown low adsorption capacities for Cr(VI) due to agglomeration of particles and are also difficult to separate from treated water. The focus of this study was on the development of conducting polymer composites for the treatment of wastewater containing Cr(VI). In particular, the aim of the research carried out was the modification of conducting polymers to obtain adsorbents with high adsorption capacities for Cr(VI) that are well-suited towards water treatment applications. Three novel conducting polymer composites were prepared in this study, namely, polypyrrole/2,5-diaminobenzenesulfonic acid (PPy/DABSA) composite, polypyrrole-polyaniline/iron oxide (PPy-PANI/Fe3O4) magnetic nanocomposite and polypyrrole-m-phenylenediamine (PPy-mPD) polymer for the desired application of removing Cr(VI) from industrial wastewater. The composites were synthesized easily and effectively by in situ chemical oxidative polymerization and their physicochemical properties characterized using various techniques including attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area analysis. Batch studies were carried out to investigate the effect of parameters such as initial solution pH, adsorbent dose, initial Cr(VI) concentration, temperature and co-existing ions in solution on Cr(VI) removal by the different composites...
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The inorganic chemistry and geochemical evolution of pans in the Mpumalanga Lakes District, South Africa
- Authors: Russell, Jennifer Lee
- Date: 2009-11-06
- Subjects: Pans (Geomorphology) , Water chemistry , Chemistry, Inorganic , Mpumalanga (South Africa)
- Type: Thesis
- Identifier: uj:8636 , http://hdl.handle.net/10210/2994
- Description: Master of Science , Despite Chrissie Lake being South Africa’s largest freshwater lake, the chemistry of this lake and the surrounding lakes and pans in the Mpumalanga Lake District has never been studied in detail. These closed systems show varying chemistry while being in very close proximity to one another, adding to the uniqueness of this area where pans, usually typical of arid regions, are found in a humid area. The factors affecting the water chemistry of these lakes needed to be identified and explained. In order to evaluate the water chemistry in this unique environment, water samples were taken at the end of the wet and dry seasons, in April and September 2007 respectively. The major pans were sampled, as were adjacent fountains or springs, indicative of the perched groundwater aquifers found in this area, as well as borehole water from the surrounding farms. Alkalinity was determined by manual titration upon returning from the field while pH and conductivity measurements were performed on site. Major cations and anions were analysed for using ICP-OES and Ion Chromatography respectively. Sediment samples were collected from the floor of each pan in the summer sampling and the mineralogy determined by X-ray diffraction (XRD). During September 2007 sampling, precipitates found on the floors and banks of the pans were also collected and analysed using XRD, to identify mineral species precipitating from solution. Results from the above analyses show that each pan in the MLD has a unique chemistry, which cannot be inferred from neighbouring pans. The inorganic chemistry differs from pan to pan as a result of these separate, closed systems being at different stages of the evaporation process. Throughout the path from groundwater to the pan, waters are subject to mineral dissolution and precipitation, adsorption and biological mechanisms, which continually add or remove solutes from solution. Although seemingly simple, there are certainly other factors that play a role in the evolution of the water chemistry. Key to the current inorganic chemistry is the balance between import and export of solutes. The groundwater, predominantly the perched aquifer water, brings solutes into the pans and blowouts of precipitates on the pan floor at the end of the dry season, when the wind is strongest, results in the export of solutes. This process is significant in maintaining the overall freshness of the pans in the MLD, contrasting to their western counter parts that evolve to highly saline saltpans. Other factors such as the periodicity of pans drying completely, the surface area to catchment area ratio (CA/SA), the formation and dissolution of efflorescent crusts and the presence or absence of reeds all have varying effects on the water chemistry of the lakes and pans. Significantly, the amount of evaporative concentration that a pan evolves through has been shown to be dependant on the CA/SA ratio with pans having larger ratios being lower in salinity compared to those with low ratios being the most saline pans. The reservoir available to the pans with the large catchment areas sustains these pans through the dry months and slows the progression of evaporation. It is clear that the factors affecting the hydrochemistry of the pan waters can not be simplified to a single process affecting a single dilute inflow of water to produce our final solution of evaporated pan water. Instead, water in the pans reflects a long-term evolution of solute species, with some memory effect remaining after each season of evaporation. The result is an accumulation of solutes as they are added continuously via dilute inflow and then removed from the waters at various times, particularly during dry periods when evaporite minerals are formed and transported out of the system.
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- Authors: Russell, Jennifer Lee
- Date: 2009-11-06
- Subjects: Pans (Geomorphology) , Water chemistry , Chemistry, Inorganic , Mpumalanga (South Africa)
- Type: Thesis
- Identifier: uj:8636 , http://hdl.handle.net/10210/2994
- Description: Master of Science , Despite Chrissie Lake being South Africa’s largest freshwater lake, the chemistry of this lake and the surrounding lakes and pans in the Mpumalanga Lake District has never been studied in detail. These closed systems show varying chemistry while being in very close proximity to one another, adding to the uniqueness of this area where pans, usually typical of arid regions, are found in a humid area. The factors affecting the water chemistry of these lakes needed to be identified and explained. In order to evaluate the water chemistry in this unique environment, water samples were taken at the end of the wet and dry seasons, in April and September 2007 respectively. The major pans were sampled, as were adjacent fountains or springs, indicative of the perched groundwater aquifers found in this area, as well as borehole water from the surrounding farms. Alkalinity was determined by manual titration upon returning from the field while pH and conductivity measurements were performed on site. Major cations and anions were analysed for using ICP-OES and Ion Chromatography respectively. Sediment samples were collected from the floor of each pan in the summer sampling and the mineralogy determined by X-ray diffraction (XRD). During September 2007 sampling, precipitates found on the floors and banks of the pans were also collected and analysed using XRD, to identify mineral species precipitating from solution. Results from the above analyses show that each pan in the MLD has a unique chemistry, which cannot be inferred from neighbouring pans. The inorganic chemistry differs from pan to pan as a result of these separate, closed systems being at different stages of the evaporation process. Throughout the path from groundwater to the pan, waters are subject to mineral dissolution and precipitation, adsorption and biological mechanisms, which continually add or remove solutes from solution. Although seemingly simple, there are certainly other factors that play a role in the evolution of the water chemistry. Key to the current inorganic chemistry is the balance between import and export of solutes. The groundwater, predominantly the perched aquifer water, brings solutes into the pans and blowouts of precipitates on the pan floor at the end of the dry season, when the wind is strongest, results in the export of solutes. This process is significant in maintaining the overall freshness of the pans in the MLD, contrasting to their western counter parts that evolve to highly saline saltpans. Other factors such as the periodicity of pans drying completely, the surface area to catchment area ratio (CA/SA), the formation and dissolution of efflorescent crusts and the presence or absence of reeds all have varying effects on the water chemistry of the lakes and pans. Significantly, the amount of evaporative concentration that a pan evolves through has been shown to be dependant on the CA/SA ratio with pans having larger ratios being lower in salinity compared to those with low ratios being the most saline pans. The reservoir available to the pans with the large catchment areas sustains these pans through the dry months and slows the progression of evaporation. It is clear that the factors affecting the hydrochemistry of the pan waters can not be simplified to a single process affecting a single dilute inflow of water to produce our final solution of evaporated pan water. Instead, water in the pans reflects a long-term evolution of solute species, with some memory effect remaining after each season of evaporation. The result is an accumulation of solutes as they are added continuously via dilute inflow and then removed from the waters at various times, particularly during dry periods when evaporite minerals are formed and transported out of the system.
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Die voorkoms en aard van besoedeling en die effek daarvan op die biologie en waterchemie van die Elsburgspruitsisteem
- Van der Merwe, Christiaan Gideon
- Authors: Van der Merwe, Christiaan Gideon
- Date: 2014-06-11
- Subjects: Water chemistry , Water - Pollution - South Africa - Elsburg Spruit , Water pollution
- Type: Thesis
- Identifier: uj:11501 , http://hdl.handle.net/10210/11197
- Description: M.Sc. (Zoology) , An investigation was made into the water chemistry, bacteriology and macroinvertebrate fauna of the Elsburg Spruit and its major tributaries within the municipal boundaries of the City of Germiston. From the results obtained it is clear that the main stream and most of its tributaries are seriously affected by a combination of pollutants. Three types of pollution could largely be distinguished namely fecal bacterial contamination of parts of the stream system which may be related to the possible discharge in the stream of domestic sewage. This in turn may be a major source of organic enrichment of the water of the stream at some places. Acid pollution associated with high mineral loads and heavy metal concentrations which in the latter case could be traced to mining regions and industrial areas in the catchment area of the system. Despite the serious disturbance of stream conditions in the upper region of the Elsburg Spruit some recovery does in fact take place in the lower lying regions of the Elsburg Spruit where the stream flows for several kilometers through a natural vlei area. Certain recommendations are made concerning the location and possible elimination of the major sources of pollution.
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- Authors: Van der Merwe, Christiaan Gideon
- Date: 2014-06-11
- Subjects: Water chemistry , Water - Pollution - South Africa - Elsburg Spruit , Water pollution
- Type: Thesis
- Identifier: uj:11501 , http://hdl.handle.net/10210/11197
- Description: M.Sc. (Zoology) , An investigation was made into the water chemistry, bacteriology and macroinvertebrate fauna of the Elsburg Spruit and its major tributaries within the municipal boundaries of the City of Germiston. From the results obtained it is clear that the main stream and most of its tributaries are seriously affected by a combination of pollutants. Three types of pollution could largely be distinguished namely fecal bacterial contamination of parts of the stream system which may be related to the possible discharge in the stream of domestic sewage. This in turn may be a major source of organic enrichment of the water of the stream at some places. Acid pollution associated with high mineral loads and heavy metal concentrations which in the latter case could be traced to mining regions and industrial areas in the catchment area of the system. Despite the serious disturbance of stream conditions in the upper region of the Elsburg Spruit some recovery does in fact take place in the lower lying regions of the Elsburg Spruit where the stream flows for several kilometers through a natural vlei area. Certain recommendations are made concerning the location and possible elimination of the major sources of pollution.
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Akkumulering van swaarmetale in 'n myn- en nywerheidsbesoedelde meerekosisteem
- Authors: De Wet, Louisa Magdalena
- Date: 2014-12-01
- Subjects: Heavy metals - Environmental aspects , Water chemistry , Water - Pollution - South Africa
- Type: Thesis
- Identifier: http://ujcontent.uj.ac.za8080/10210/376065 , uj:13133 , http://hdl.handle.net/10210/13108
- Description: M.Sc. (Zoology) , Please refer to full text to view abstract
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- Authors: De Wet, Louisa Magdalena
- Date: 2014-12-01
- Subjects: Heavy metals - Environmental aspects , Water chemistry , Water - Pollution - South Africa
- Type: Thesis
- Identifier: http://ujcontent.uj.ac.za8080/10210/376065 , uj:13133 , http://hdl.handle.net/10210/13108
- Description: M.Sc. (Zoology) , Please refer to full text to view abstract
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Die voorkoms en akkumulering van geselekteerde swaarmetale in die rioolbesoedelde, organiesverrykte Elsburgspruit-Natalspruit vlei-ekosisteem
- Authors: Van Eeden, Pieter Hermanus
- Date: 2015-08-18
- Subjects: Heavy metals - Environmental aspects , Water - Pollution - South Africa , Water chemistry
- Type: Thesis
- Identifier: uj:13902 , http://hdl.handle.net/10210/14250
- Description: M.Sc. (Zoology) , Please refer to full text to view abstract
- Full Text:
- Authors: Van Eeden, Pieter Hermanus
- Date: 2015-08-18
- Subjects: Heavy metals - Environmental aspects , Water - Pollution - South Africa , Water chemistry
- Type: Thesis
- Identifier: uj:13902 , http://hdl.handle.net/10210/14250
- Description: M.Sc. (Zoology) , Please refer to full text to view abstract
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Modelling studies of interactions between natural organic matter and metals : effects on cooling water precipitation potentials in power generation plants
- Authors: Parshotam, Heena
- Date: 2014
- Subjects: Water chemistry , Organic compounds , Electric power-plants , Organic water pollutants
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/62578 , uj:16950
- Description: Abstract: Please refer to full text to view abstract , D.Phil. (Chemistry)
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- Authors: Parshotam, Heena
- Date: 2014
- Subjects: Water chemistry , Organic compounds , Electric power-plants , Organic water pollutants
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/62578 , uj:16950
- Description: Abstract: Please refer to full text to view abstract , D.Phil. (Chemistry)
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Characterization of the natural organic matter in industrial cooling water
- Authors: Khumalo, Thomas Linda
- Date: 2008-06-17T13:37:39Z
- Subjects: Calcium carbonate , Water chemistry , Electric power plants , Organic compounds
- Type: Thesis
- Identifier: uj:2866 , http://hdl.handle.net/10210/629
- Description: Scaling due to calcium carbonate precipitation is a major problem in cooling water circuits in many of Eskom power stations. Some earlier studies have suggested that the natural organic matter (NOM) present in the cooling water may reduce the amount of scaling by limiting the formation of calcium carbonate precipitation. It is therefore the interest of this study to investigate further the role of the NOM in calcium carbonate precipitation at Hendrina power station. The raw water and cooling water were analysed for the major metal ions, anions, alkalinity, conductivity and total organic matter to determine the precipitation potentials of calcite and aragonite using MINTEQA2 speciation program. The NOM was isolated from the raw and cooling water using ion exchange resins, XAD-8/XAD-4 resins and ultrafiltration membranes with molecular weight cut-offs of 100 kDa, 10 kDa and 1 kDa. The isolated fractions were then characterized by ultraviolet and visible absorbance methods and high performance size exclusion chromatography. The effect of the isolated fractions of the NOM from the cooling water on calcium carbonate precipitation was then investigated. The results indicated the presence calcium carbonate precipitation in the cooling water, but the raw water was undersaturated with calcium carbonate. The NOM isolated from the raw water indicated the predominance of the hydrophobic acid NOM (74.17 %) and to a lower extent the presence of hydrophilic acid NOM (34.49%). The NOM isolated from the cooling water also showed the predominance of the hydrophobic acid NOM (69.25 %) and to a lower extent the presence of the hydrophilic neutral acid NOM (20.13 %) and minimal presence of hydrophilic acid NOM (9.51 %). The results obtained from high pressure size exclusion chromatography analyses indicated that in both the raw water and cooling water the NOM was having a low molecular weight (<13.2030 kDa). The specific ultraviolet absorbance (SUVA) of the raw water was high (>4) which also suggested that it contained predominantly hydrophobic NOM and that of the cooling i water was in the range 2-4 suggesting that it contained a mixture of the hydrophobic and hydrophilic acid NOM. The hydrophobic acid, hydrophilic acid and hydrophilic neutral acid NOM fractions isolated from the cooling water reduced the amount of calcium carbonate precipitate formed in synthetic water sample. This effect was more pronounced with hydrophobic and hydrophilic acid NOM fractions than with the hydrophilic neutral acid NOM fraction. , Dr. M. Shumane
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- Authors: Khumalo, Thomas Linda
- Date: 2008-06-17T13:37:39Z
- Subjects: Calcium carbonate , Water chemistry , Electric power plants , Organic compounds
- Type: Thesis
- Identifier: uj:2866 , http://hdl.handle.net/10210/629
- Description: Scaling due to calcium carbonate precipitation is a major problem in cooling water circuits in many of Eskom power stations. Some earlier studies have suggested that the natural organic matter (NOM) present in the cooling water may reduce the amount of scaling by limiting the formation of calcium carbonate precipitation. It is therefore the interest of this study to investigate further the role of the NOM in calcium carbonate precipitation at Hendrina power station. The raw water and cooling water were analysed for the major metal ions, anions, alkalinity, conductivity and total organic matter to determine the precipitation potentials of calcite and aragonite using MINTEQA2 speciation program. The NOM was isolated from the raw and cooling water using ion exchange resins, XAD-8/XAD-4 resins and ultrafiltration membranes with molecular weight cut-offs of 100 kDa, 10 kDa and 1 kDa. The isolated fractions were then characterized by ultraviolet and visible absorbance methods and high performance size exclusion chromatography. The effect of the isolated fractions of the NOM from the cooling water on calcium carbonate precipitation was then investigated. The results indicated the presence calcium carbonate precipitation in the cooling water, but the raw water was undersaturated with calcium carbonate. The NOM isolated from the raw water indicated the predominance of the hydrophobic acid NOM (74.17 %) and to a lower extent the presence of hydrophilic acid NOM (34.49%). The NOM isolated from the cooling water also showed the predominance of the hydrophobic acid NOM (69.25 %) and to a lower extent the presence of the hydrophilic neutral acid NOM (20.13 %) and minimal presence of hydrophilic acid NOM (9.51 %). The results obtained from high pressure size exclusion chromatography analyses indicated that in both the raw water and cooling water the NOM was having a low molecular weight (<13.2030 kDa). The specific ultraviolet absorbance (SUVA) of the raw water was high (>4) which also suggested that it contained predominantly hydrophobic NOM and that of the cooling i water was in the range 2-4 suggesting that it contained a mixture of the hydrophobic and hydrophilic acid NOM. The hydrophobic acid, hydrophilic acid and hydrophilic neutral acid NOM fractions isolated from the cooling water reduced the amount of calcium carbonate precipitate formed in synthetic water sample. This effect was more pronounced with hydrophobic and hydrophilic acid NOM fractions than with the hydrophilic neutral acid NOM fraction. , Dr. M. Shumane
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