Phosphorylated carbon nanotube-cyclodextrin/silver-doped titania nanobiocomposites for water purification
- Authors: Leudjo Taka, Anny
- Date: 2018
- Subjects: Water - Purification , Cyclodextrins , Titanium dioxide , Carbon nanotubes , Nanobiotechnology
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/278734 , uj:29917
- Description: Ph.D. (Chemistry) , Abstract: Nowadays, the shortage of water resources is the major concern around the world and especially in Southern Africa. The challenge is to develop an effective method to recycle wastewater through adequate treatment. That is to design a water treatment material able to remove the pollutants from wastewater effectively and efficiently to the accepted levels. In this regard, the aim of this research project was to develop a new nanomaterial which was used as adsorbent and disinfectant to remove all the three classes of water pollutants (inorganic, organic and pathogenic microorganism) from wastewater. In this study, phosphorylated multiwalled carbon nanotube-cyclodextrin/silver doped titania (pMWCNT-βCD/TiO2-Ag) was synthesized, using a combined process of amidation reaction, cross-linking polymerization and the sol-gel method. For a better evaluation of the target material, the insoluble nanosponges β-cyclodextrin (βCD) polymer and pMWCNT-βCD composite polymer were also synthesized for comparison purposes. The prepared nanostructured materials were fully characterized using thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), Brunauer-Emmett-Teller (BET) method, electron microscopy, and spectroscopy techniques. Fourier-transform infrared (FTIR) spectroscopy was used to confirm the presence of functional groups on the surface of modified MWCNTs, and the polymerization reaction. X-ray photoelectron spectroscopy (XPS) was employed to further confirm the presence of functional groups on the surface of the nanomaterials synthesized and to provide the percentage elemental composition with binding energies. Laser Raman showed the presence of MWCNT, βCD, and TiO2 in the nanocomposite. The anatase crystalline form of TiO2 in the samples synthesized was confirmed by X-ray diffraction (XRD) spectroscopy analysis. Transmission electron microscopy (TEM) analysis confirmed the structural morphology of the new biopolymer nanocomposite (pMWCNT-βCD/TiO2-Ag) as a sponge-like structure which showed a good dispersion of Ag nanoparticles. The BET surface area of the newly developed pMWCNT-βCD/TiO2-Ag was very high (352.55 m2/g), and this favored the use of this new nanomaterial as an adsorbent for the effective removal of pollutants from synthetic i.e. model wastewater and mine effluent samples...
- Full Text:
- Authors: Leudjo Taka, Anny
- Date: 2018
- Subjects: Water - Purification , Cyclodextrins , Titanium dioxide , Carbon nanotubes , Nanobiotechnology
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/278734 , uj:29917
- Description: Ph.D. (Chemistry) , Abstract: Nowadays, the shortage of water resources is the major concern around the world and especially in Southern Africa. The challenge is to develop an effective method to recycle wastewater through adequate treatment. That is to design a water treatment material able to remove the pollutants from wastewater effectively and efficiently to the accepted levels. In this regard, the aim of this research project was to develop a new nanomaterial which was used as adsorbent and disinfectant to remove all the three classes of water pollutants (inorganic, organic and pathogenic microorganism) from wastewater. In this study, phosphorylated multiwalled carbon nanotube-cyclodextrin/silver doped titania (pMWCNT-βCD/TiO2-Ag) was synthesized, using a combined process of amidation reaction, cross-linking polymerization and the sol-gel method. For a better evaluation of the target material, the insoluble nanosponges β-cyclodextrin (βCD) polymer and pMWCNT-βCD composite polymer were also synthesized for comparison purposes. The prepared nanostructured materials were fully characterized using thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), Brunauer-Emmett-Teller (BET) method, electron microscopy, and spectroscopy techniques. Fourier-transform infrared (FTIR) spectroscopy was used to confirm the presence of functional groups on the surface of modified MWCNTs, and the polymerization reaction. X-ray photoelectron spectroscopy (XPS) was employed to further confirm the presence of functional groups on the surface of the nanomaterials synthesized and to provide the percentage elemental composition with binding energies. Laser Raman showed the presence of MWCNT, βCD, and TiO2 in the nanocomposite. The anatase crystalline form of TiO2 in the samples synthesized was confirmed by X-ray diffraction (XRD) spectroscopy analysis. Transmission electron microscopy (TEM) analysis confirmed the structural morphology of the new biopolymer nanocomposite (pMWCNT-βCD/TiO2-Ag) as a sponge-like structure which showed a good dispersion of Ag nanoparticles. The BET surface area of the newly developed pMWCNT-βCD/TiO2-Ag was very high (352.55 m2/g), and this favored the use of this new nanomaterial as an adsorbent for the effective removal of pollutants from synthetic i.e. model wastewater and mine effluent samples...
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Photodegradation of dye effluent whilst monitoring the fate and behaviour of TiO2 in a simulated photocatalytic treatment plant
- Authors: Mahlalela, Lwazi Charles
- Date: 2017
- Subjects: Photocatalysis , Water - Purification - Photocatalysis , Titanium dioxide , Nanocomposites (Materials) , Dyes and dyeing - Environmental aspects
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/235955 , uj:24140
- Description: M.Sc. (Chemistry) , Abstract: Titania (TiO2) has been seen as one of the best semiconductor photocatalysts capable to photodegrade organic pollutants from water. This presents a method that textile industries can use to remove organic dyes from their effluents before release. The photocatalytic activity of TiO2 nanoparticles was conducted to also examine the influence of electron acceptors on the removal of dyes from water. The interaction between TiO2 nanoparticles and industrial dyes is inevitable because of the possible application of TiO2 in the removal of dyes in textile effluents. Therefore, the possible application of TiO2 in the removal of dyes compels understanding the stability of TiO2 as influenced by industrial dyes and different abiotic factors. This is important for risk assessment purposes. The stability of TiO2 nanoparticles in the presence of disperse dye-stuff was conducted as influenced by pH, ionic strength and type of electrolyte. These parameters also influenced the physicochemical properties of the nanoparticles. Understanding fate and behaviour of engineered nanomaterials (ENMs) in wastewater treatment plants (WWTPs) is important for the environmental risk assessment of ENMs. This is due to the appearance of ENMs in WWTPs that results from the wide spread application in consumer products and industrial applications. TiO2 has been reported as one of them. Thus, before environmental risk assessment can be conducted, studies at the points at which ENMs appear in high concentrations is important and WWTPs is one of them. Due to the in availability of nanoparticle test protocols, the Organisations of Economic Co-operation and Development (OECD) guidelines for testing of chemicals (303A) have been used by several researchers to study fate and behaviour of nanoparticles of interest. Therefore, the fate and behaviour of TiO2 nanoparticles was conducted following the OECD 303A. The findings of this study are summarised as follows:..
- Full Text:
- Authors: Mahlalela, Lwazi Charles
- Date: 2017
- Subjects: Photocatalysis , Water - Purification - Photocatalysis , Titanium dioxide , Nanocomposites (Materials) , Dyes and dyeing - Environmental aspects
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/235955 , uj:24140
- Description: M.Sc. (Chemistry) , Abstract: Titania (TiO2) has been seen as one of the best semiconductor photocatalysts capable to photodegrade organic pollutants from water. This presents a method that textile industries can use to remove organic dyes from their effluents before release. The photocatalytic activity of TiO2 nanoparticles was conducted to also examine the influence of electron acceptors on the removal of dyes from water. The interaction between TiO2 nanoparticles and industrial dyes is inevitable because of the possible application of TiO2 in the removal of dyes in textile effluents. Therefore, the possible application of TiO2 in the removal of dyes compels understanding the stability of TiO2 as influenced by industrial dyes and different abiotic factors. This is important for risk assessment purposes. The stability of TiO2 nanoparticles in the presence of disperse dye-stuff was conducted as influenced by pH, ionic strength and type of electrolyte. These parameters also influenced the physicochemical properties of the nanoparticles. Understanding fate and behaviour of engineered nanomaterials (ENMs) in wastewater treatment plants (WWTPs) is important for the environmental risk assessment of ENMs. This is due to the appearance of ENMs in WWTPs that results from the wide spread application in consumer products and industrial applications. TiO2 has been reported as one of them. Thus, before environmental risk assessment can be conducted, studies at the points at which ENMs appear in high concentrations is important and WWTPs is one of them. Due to the in availability of nanoparticle test protocols, the Organisations of Economic Co-operation and Development (OECD) guidelines for testing of chemicals (303A) have been used by several researchers to study fate and behaviour of nanoparticles of interest. Therefore, the fate and behaviour of TiO2 nanoparticles was conducted following the OECD 303A. The findings of this study are summarised as follows:..
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Rare earth doped Titania/Carbon nanomaterials composite photocatalysts for water treatment
- Authors: Mamba, Gcina
- Date: 2015-11-12
- Subjects: Water - Purification - Photocatalysis , Nanostructured materials , Photocatalysis , Titanium dioxide
- Type: Thesis
- Identifier: uj:14557 , http://hdl.handle.net/10210/15090
- Description: PhD. (Chemistry) , Pre-synthesised gadolinium oxide decorated multiwalled carbon nanotubes (MWCNT-Gd) were coupled with titania to form nanocomposite photocatalysts (MWCNT-Gd/TiO2) using a sol-gel method. Rare earth metal ions (Eu, Nd and Gd), nitrogen and sulphur tridoped titania were decorated on MWCNT-Gd to yield composite photocatalysts (MWCNT-Gd/Eu/Nd/Gd/N,S-TiO2) by a similar method, using thiourea as nitrogen and sulphur source. Different carbon nanomaterials were incorporated into tridoped titania to form various composite photocatalysts (MWCNT/Gd,N,S-TiO2, MWCNT/Nd,N,S-TiO2, SWCNT (single walled carbon nanotube)/Nd,N,S-TiO2 and rGO (reduced graphene oxide)/Nd,N,S-TiO2) via the sol-gel method. Likewise, gadolinium doped graphitic carbon nitride (g-C3N4-Gd3+) was obtained by heating a mixture of gadolinium nitrate hexahydrate and cyanoguanidine and subsequently hybridised with MWCNT/TiO2 using the sol-gel method to yield composite photocatalysts with varying g-C3N4-Gd3+ loadings. All the prepared photocatalysts were characterised by microscopic tools (FE/FIB-SEM-EDX, TEM), crystallographic technique (XRD), spectroscopic tools (UV-Vis, Raman and FT-IR) and nitrogen sorption technique (BET).
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- Authors: Mamba, Gcina
- Date: 2015-11-12
- Subjects: Water - Purification - Photocatalysis , Nanostructured materials , Photocatalysis , Titanium dioxide
- Type: Thesis
- Identifier: uj:14557 , http://hdl.handle.net/10210/15090
- Description: PhD. (Chemistry) , Pre-synthesised gadolinium oxide decorated multiwalled carbon nanotubes (MWCNT-Gd) were coupled with titania to form nanocomposite photocatalysts (MWCNT-Gd/TiO2) using a sol-gel method. Rare earth metal ions (Eu, Nd and Gd), nitrogen and sulphur tridoped titania were decorated on MWCNT-Gd to yield composite photocatalysts (MWCNT-Gd/Eu/Nd/Gd/N,S-TiO2) by a similar method, using thiourea as nitrogen and sulphur source. Different carbon nanomaterials were incorporated into tridoped titania to form various composite photocatalysts (MWCNT/Gd,N,S-TiO2, MWCNT/Nd,N,S-TiO2, SWCNT (single walled carbon nanotube)/Nd,N,S-TiO2 and rGO (reduced graphene oxide)/Nd,N,S-TiO2) via the sol-gel method. Likewise, gadolinium doped graphitic carbon nitride (g-C3N4-Gd3+) was obtained by heating a mixture of gadolinium nitrate hexahydrate and cyanoguanidine and subsequently hybridised with MWCNT/TiO2 using the sol-gel method to yield composite photocatalysts with varying g-C3N4-Gd3+ loadings. All the prepared photocatalysts were characterised by microscopic tools (FE/FIB-SEM-EDX, TEM), crystallographic technique (XRD), spectroscopic tools (UV-Vis, Raman and FT-IR) and nitrogen sorption technique (BET).
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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...
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- Authors: Kuvarega, Alex Tawanda
- Date: 2013-07-24
- Subjects: Water purification , Water purification - Organic compounds removal , Organic water pollutants , Titanium dioxide , Photocatalysis , Nanotubes , Carbon
- Type: Thesis
- Identifier: uj:7665 , http://hdl.handle.net/10210/8533
- Description: D.Phil. (Chemistry) , Elimination of toxic organic compounds from wastewater is currently one of the most important subjects in water-pollution control. Among the many organic pollutants are dyes and emerging pollutants such as natural organic matter (NOM). Dyes such as Eosin Yellow (EY), an anionic xanthene fluorescent dye, can originate from many sources such as textile industrial processes, paper pulp industries and agricultural processes. Most dyes are problematic because they are resistant to conventional chemical or biological water-treatment methods and therefore persist in the environment. NOM consists of a highly variable mixture of products found in water and soils. NOM is formed as a result of the decomposition of plant and animal material and is a precursor to the formation of disinfection by-products (DBP) during water disinfection. These organic compounds cause undesirable colour, taste and odour in water. NOM affects the capacity of other treatment processes to effectively remove organic micro-pollutants or inorganic species that may be present in the water. Its removal also uses up chemicals and energy and so it is expensive to treat. Titanium dioxide (TiO2) has emerged as one of the most fascinating materials in the modern era due to its semiconducting and catalytic properties. TiO2 is a large band-gap semiconductor that exists mainly in the anatase (band gap 3.2 eV) and rutile (band gap 3.0 eV) phases. Its response to UV light has led to increased interest in its application in the photocatalysis research field. It has been investigated extensively for its super hydrophilicity and use in environmental remediation and solar fuel production. In spite of extensive efforts to apply TiO2 for environmental remediation, photocatalytic activity in the visible region has remained quite low hence the ultimate goal of this research was to fabricate highly photoactive catalysts composed of non-metal, platinum-group metal (PGM) co-doped TiO2 and carbon nanotubes (CNTs) and to apply them for water purification using solar radiation...
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Doped nanotitanium dioxide for photocatalytic applications
- Dlamini, Langelihle Nsikayezwe
- Authors: Dlamini, Langelihle Nsikayezwe
- Date: 2013-07-24
- Subjects: Titanium dioxide , Nanocomposites (Materials) , Photocatalysis , Water purification - Photocatalysis
- Type: Thesis
- Identifier: uj:7685 , http://hdl.handle.net/10210/8551
- Description: D.Phil. (Chemistry) , Please refer to full text to view abstract
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- Authors: Dlamini, Langelihle Nsikayezwe
- Date: 2013-07-24
- Subjects: Titanium dioxide , Nanocomposites (Materials) , Photocatalysis , Water purification - Photocatalysis
- Type: Thesis
- Identifier: uj:7685 , http://hdl.handle.net/10210/8551
- Description: D.Phil. (Chemistry) , Please refer to full text to view abstract
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Nanostructured membranes embedded with hyperbranched polyethyleneimine (HPEI) hosts and titanium dioxide (TiO2) nanoparticles for water purification
- Authors: Mathumba, Penny
- Date: 2016
- Subjects: Water - Purification , Water - Purification - Membrane filtration , Titanium dioxide , Nanotechnology
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/84654 , uj:19247
- Description: Abstract: Water scarcity is a huge challenge throughout the world. The capacity of water in South African water systems will decrease dramatically in the next 10 years. Moreover the removal of pollutants from industrial and municipal water has become a challenge for water treatment industries. In particular, the textile industry consumes large volumes of water during dyeing processes. Thus textile industries are regarded as major polluters in the world. Azo dyes (e.g. Methyl Orange and Methyl Blue) constitute about 70% of the dyes used in the textile industry. The water discharged from textile industries is highly coloured and contains compounds that are complex in nature. Coloured water prevents the penetration of light into rivers and lakes thus affecting the process of photosynthesis and this affects the natural flora and fauna. Moreover, the improper discharge of untreated coloured dye effluent into the environment has resulted in numerous public protests. Methyl orange has been reported to be toxic and mutagenic to animals. Moreover, most of these dyes are also not effectively removed by the use of conventional biological treatment processes since they are non-biodegradable... , M.Sc.
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- Authors: Mathumba, Penny
- Date: 2016
- Subjects: Water - Purification , Water - Purification - Membrane filtration , Titanium dioxide , Nanotechnology
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/84654 , uj:19247
- Description: Abstract: Water scarcity is a huge challenge throughout the world. The capacity of water in South African water systems will decrease dramatically in the next 10 years. Moreover the removal of pollutants from industrial and municipal water has become a challenge for water treatment industries. In particular, the textile industry consumes large volumes of water during dyeing processes. Thus textile industries are regarded as major polluters in the world. Azo dyes (e.g. Methyl Orange and Methyl Blue) constitute about 70% of the dyes used in the textile industry. The water discharged from textile industries is highly coloured and contains compounds that are complex in nature. Coloured water prevents the penetration of light into rivers and lakes thus affecting the process of photosynthesis and this affects the natural flora and fauna. Moreover, the improper discharge of untreated coloured dye effluent into the environment has resulted in numerous public protests. Methyl orange has been reported to be toxic and mutagenic to animals. Moreover, most of these dyes are also not effectively removed by the use of conventional biological treatment processes since they are non-biodegradable... , M.Sc.
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Tio₂nanocatalysts: synthesis, layer-by-layer immobilisation on glass slides and their support on carbon-covered alumina (cca) for application in drinking water treatment
- Mahlambi, Mphilisi Mciniseli
- Authors: Mahlambi, Mphilisi Mciniseli
- Date: 2012-08-16
- Subjects: Nanocatalysts , Nanochemistry , Catalysts synthesis , Titanium dioxide , Rutile , Analytic chemistry , Drinking water purification
- Type: Thesis
- Identifier: uj:9551 , http://hdl.handle.net/10210/5977
- Description: D.Phil. , Clean water (i.e. water that is free of toxic chemicals and pathogens) is essential to human health and in South Africa the demand is fast exceeding the supply. The prevalence of toxic contaminants in water remains a huge challenge for water supplying companies and municipalities. However, the presently used water treatment technologies either fail to remove these contaminants to acceptable levels or they transform them into more toxic substances (e.g., DBPs). Nanocatalysts, especially TiO2 (titania) have a proven potential to treat ‘difficult-to-remove’ contaminants and hence are expected to play an important role in solving many serious environmental and pollution challenges. In this study TiO2 nanocatalysts were used for the degradation of Rhodamine B dye both under UV and visible light irradiation. Two phases of titania, i.e. anatase and rutile phases, were compared for the degradation of Rhodamine B under UV light irradiation. The anatase titania was found to be more photocatalytically active for the degradation of Rhodamine B than the rutile phase. It completely degraded 100 mg ℓ–1 (100 mℓ) of Rhodamine B within 270 min and was two times more photocatalytically active than the rutile phase (Kapp of 0.017 min–1 compared to 0.0089 min–1). To extend the band edge of the titania nanocatalysts towards visible-light, TiO2 was doped with metal ions (Ag, Co, Ni and Pd). These metal-ion-doped titania nanocatalysts were photocatalytically active under visible-light illumination. The Pd-doped titania had the highest photodegradation efficiencies, followed by Ag-doped and Co-doped, while Ni-doped had the lowest. The optimum metal-ion loading percentage was found to be at 0.4%, with the exception of Co-doped titania as it had the highest efficiencies at 1% loadings. The free and metal-ion-doped titania nanocatalysts were embedded on carbon-covered alumina (CCA) supports. The CCA-supported TiO2 nanocatalysts were more photocatalytically active under visible light illumination than they were under UV-light irradiation. The CCA-supported metal-ion-doped titania nanocatalysts were more photocatalytically active under visible light than their unsupported counterparts. The CCA-supported Pd-TiO2 nanocatalysts were the most active while CCA-supported Ni-TiO2 catalysts were the least active. The improved photocatalytic activities observed were as a result of increased surface areas of the CCA-supported nanocatalysts. Also, supporting the nanocatalysts did not destroy the anatase phase of the titania while doping with metal ions and supporting on CCAs resulted in decreased band gap energies, hence the visible-light photocatalytic activities. Finally, the metal-ion-doped titania nanocatalysts were supported on glass slides using the layer-by-layer thin film self-assembly technique. This was to overcome the aggregation and post treatment problems associated with the use of TiO2 in suspension form. PAH and PSS were the polyelectrolytes used. These metal-ion-doped titania thin films were highly porous and strongly adhered by the polyelectrolytes onto the glass slides. The thin films were photocatalytically active for the degradation of Rhodamine B under visible light irradiation. The photocatalytic degradation efficiencies observed were similar for all four metal-ions (i.e. Ag, Co, Ni and Pd) with average degradation of 30%, 50%, 70% and 90% for 5 catalysts (5 glass slides) of 1, 3, 5 and 10 bi-layers, respectively, after 330 min. Although, these were less active than the suspended titania nanocatalysts, this study proved as a stepping stone towards large scale use of titania nanocatalysts using solar energy as the irradiation source. Also, catalyst reusability studies were performed and the PAH/PSS m-TiO2 thin films were found to be highly stable over the five cycles it was tested for.
- Full Text:
- Authors: Mahlambi, Mphilisi Mciniseli
- Date: 2012-08-16
- Subjects: Nanocatalysts , Nanochemistry , Catalysts synthesis , Titanium dioxide , Rutile , Analytic chemistry , Drinking water purification
- Type: Thesis
- Identifier: uj:9551 , http://hdl.handle.net/10210/5977
- Description: D.Phil. , Clean water (i.e. water that is free of toxic chemicals and pathogens) is essential to human health and in South Africa the demand is fast exceeding the supply. The prevalence of toxic contaminants in water remains a huge challenge for water supplying companies and municipalities. However, the presently used water treatment technologies either fail to remove these contaminants to acceptable levels or they transform them into more toxic substances (e.g., DBPs). Nanocatalysts, especially TiO2 (titania) have a proven potential to treat ‘difficult-to-remove’ contaminants and hence are expected to play an important role in solving many serious environmental and pollution challenges. In this study TiO2 nanocatalysts were used for the degradation of Rhodamine B dye both under UV and visible light irradiation. Two phases of titania, i.e. anatase and rutile phases, were compared for the degradation of Rhodamine B under UV light irradiation. The anatase titania was found to be more photocatalytically active for the degradation of Rhodamine B than the rutile phase. It completely degraded 100 mg ℓ–1 (100 mℓ) of Rhodamine B within 270 min and was two times more photocatalytically active than the rutile phase (Kapp of 0.017 min–1 compared to 0.0089 min–1). To extend the band edge of the titania nanocatalysts towards visible-light, TiO2 was doped with metal ions (Ag, Co, Ni and Pd). These metal-ion-doped titania nanocatalysts were photocatalytically active under visible-light illumination. The Pd-doped titania had the highest photodegradation efficiencies, followed by Ag-doped and Co-doped, while Ni-doped had the lowest. The optimum metal-ion loading percentage was found to be at 0.4%, with the exception of Co-doped titania as it had the highest efficiencies at 1% loadings. The free and metal-ion-doped titania nanocatalysts were embedded on carbon-covered alumina (CCA) supports. The CCA-supported TiO2 nanocatalysts were more photocatalytically active under visible light illumination than they were under UV-light irradiation. The CCA-supported metal-ion-doped titania nanocatalysts were more photocatalytically active under visible light than their unsupported counterparts. The CCA-supported Pd-TiO2 nanocatalysts were the most active while CCA-supported Ni-TiO2 catalysts were the least active. The improved photocatalytic activities observed were as a result of increased surface areas of the CCA-supported nanocatalysts. Also, supporting the nanocatalysts did not destroy the anatase phase of the titania while doping with metal ions and supporting on CCAs resulted in decreased band gap energies, hence the visible-light photocatalytic activities. Finally, the metal-ion-doped titania nanocatalysts were supported on glass slides using the layer-by-layer thin film self-assembly technique. This was to overcome the aggregation and post treatment problems associated with the use of TiO2 in suspension form. PAH and PSS were the polyelectrolytes used. These metal-ion-doped titania thin films were highly porous and strongly adhered by the polyelectrolytes onto the glass slides. The thin films were photocatalytically active for the degradation of Rhodamine B under visible light irradiation. The photocatalytic degradation efficiencies observed were similar for all four metal-ions (i.e. Ag, Co, Ni and Pd) with average degradation of 30%, 50%, 70% and 90% for 5 catalysts (5 glass slides) of 1, 3, 5 and 10 bi-layers, respectively, after 330 min. Although, these were less active than the suspended titania nanocatalysts, this study proved as a stepping stone towards large scale use of titania nanocatalysts using solar energy as the irradiation source. Also, catalyst reusability studies were performed and the PAH/PSS m-TiO2 thin films were found to be highly stable over the five cycles it was tested for.
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Preparation of doped nanotitanium dioxide (TIO2) immobilized on polyethersulphone (PES) nanofiberes for photocatalytic degradation of water pollutants
- Authors: Chabalala, Mandla Brian
- Date: 2016
- Subjects: Water - Purification - Photocatalysis , Photocatalysis , Nanofiltration , Titanium dioxide
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/84406 , uj:19216
- Description: Abstract: As the world’s population continue to grow annually, the demand of drinking water also increases. Countries that are facing water scarcity are currently facing high demand rates of clean water. One of the major contributors to water scarcity is water pollution; this is often caused by the release of wastewater by various sectors which include factories, industries and laboratories, among others. Such wastewater contains toxic materials which end up in drinking water sources and these materials are suspected of being endocrine-disruptive-chemicals (EDCs). The increase in concentrations of contaminants (particularly dyes) in water show that conventional wastewater treatments methods are not efficient enough, hence advanced technologies such as Advanced Oxidation Processes (AOPs) should be implemented to treat persistent contaminants in water. AOPs are characterized by the production of highly reactive hydroxyl (HO•) and superoxide (O2-•) anion radicals, which are suitable for a rapid, continuous and indiscriminative reaction with organic compounds inducing almost complete degradation. Such AOPs include the Fenton’s process which uses peroxide-iron (II) (H2O2/Fe2+) as the Fenton reagent and Photocatalysis which makes use of semiconductors such as titanium dioxide (TiO2). AOPs are classified as clean technology for the treatment of wastewater and can degrade micro pollutants with reaction rate of up to 109 Lmol-1s-1 yielding CO2, H2O and inorganic ions as the final products Pristine and doped TiO2 photocatalysts were prepared using a modified sol-gel method in both acidic and basic medium. The loading of N was varied from 1 to 5 %. Polyethersulphone (PES) nanofibers were electrospun from a PES polymer solution that was prepared by dissolving PES in N,N-Dimethylfomamide (DMF) at room temperature overnight. The polymer solutions of concentration 18 to 29 % PES/DMF (m/m %) were obtained. The resulting solutions were electrospun at the following conditions: 20 - 25 cm tip to collector distance, 12 kV working voltage and 0.5 ml flow rate. The electrospinning of PES/Photocatalyst (PES/PC) nanofiber was performed under the optimized conditions of PES nanofibers. The photocatalysts loading was varied between 1.5, 2 and 2.5 % while PES was , M.Sc. (Chemistry)
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- Authors: Chabalala, Mandla Brian
- Date: 2016
- Subjects: Water - Purification - Photocatalysis , Photocatalysis , Nanofiltration , Titanium dioxide
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/84406 , uj:19216
- Description: Abstract: As the world’s population continue to grow annually, the demand of drinking water also increases. Countries that are facing water scarcity are currently facing high demand rates of clean water. One of the major contributors to water scarcity is water pollution; this is often caused by the release of wastewater by various sectors which include factories, industries and laboratories, among others. Such wastewater contains toxic materials which end up in drinking water sources and these materials are suspected of being endocrine-disruptive-chemicals (EDCs). The increase in concentrations of contaminants (particularly dyes) in water show that conventional wastewater treatments methods are not efficient enough, hence advanced technologies such as Advanced Oxidation Processes (AOPs) should be implemented to treat persistent contaminants in water. AOPs are characterized by the production of highly reactive hydroxyl (HO•) and superoxide (O2-•) anion radicals, which are suitable for a rapid, continuous and indiscriminative reaction with organic compounds inducing almost complete degradation. Such AOPs include the Fenton’s process which uses peroxide-iron (II) (H2O2/Fe2+) as the Fenton reagent and Photocatalysis which makes use of semiconductors such as titanium dioxide (TiO2). AOPs are classified as clean technology for the treatment of wastewater and can degrade micro pollutants with reaction rate of up to 109 Lmol-1s-1 yielding CO2, H2O and inorganic ions as the final products Pristine and doped TiO2 photocatalysts were prepared using a modified sol-gel method in both acidic and basic medium. The loading of N was varied from 1 to 5 %. Polyethersulphone (PES) nanofibers were electrospun from a PES polymer solution that was prepared by dissolving PES in N,N-Dimethylfomamide (DMF) at room temperature overnight. The polymer solutions of concentration 18 to 29 % PES/DMF (m/m %) were obtained. The resulting solutions were electrospun at the following conditions: 20 - 25 cm tip to collector distance, 12 kV working voltage and 0.5 ml flow rate. The electrospinning of PES/Photocatalyst (PES/PC) nanofiber was performed under the optimized conditions of PES nanofibers. The photocatalysts loading was varied between 1.5, 2 and 2.5 % while PES was , M.Sc. (Chemistry)
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A bi-faceted adsorptive performance of TiO₂-Coated carbon for the removal of fluorides in water
- Authors: Vilakati, Bongekile R.
- Date: 2015
- Subjects: Water - Purification , Fluorides , Adsorption , Titanium dioxide , Carbon
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/58770 , uj:16501
- Description: Abstract: Please refer to full text to view abstract , M.Sc. (Chemistry)
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- Authors: Vilakati, Bongekile R.
- Date: 2015
- Subjects: Water - Purification , Fluorides , Adsorption , Titanium dioxide , Carbon
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/58770 , uj:16501
- Description: Abstract: Please refer to full text to view abstract , M.Sc. (Chemistry)
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A study on Titanium Dioxide Nanoparticles synthesized from Titanium Isopropoxide under Silar-Induced Gel Method : transition from Anatase to Rutile structure
- Nkele, Agnes C., Chime, Ugochi K., Asogwa, Leonard, Nwanya, Assumpta C., Nwankwo, Uba, Ukoba, K., Jen, T. C., Maaza, M., Ezema, Fabian I.
- Authors: Nkele, Agnes C. , Chime, Ugochi K. , Asogwa, Leonard , Nwanya, Assumpta C. , Nwankwo, Uba , Ukoba, K. , Jen, T. C. , Maaza, M. , Ezema, Fabian I.
- Date: 2019
- Subjects: SILAR , Titanium dioxide , Nanoparticles
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/404406 , uj:33913 , Citation: Nkele, A.C. et al. 2019. A study on Titanium Dioxide Nanoparticles synthesized from Titanium Isopropoxide under Silar-Induced Gel Method : transition from Anatase to Rutile structure.
- Description: Abstract: Successive ionic layer adsorption and reaction (SILAR) method was adopted in synthesizing titanium dioxide nanoparticles at various temperatures so as to investigate their morphological, structural, elemental, optical, chemical bond and photoluminescence properties. The as-prepared nanoparticles were characterized with scanning electron microscopy (SEM), X-ray diffractometry (XRD), transmission electron microscopy (TEM), selected area electron diffractometer (SAED), energy dispersive x-ray spectroscopy (EDX), UV-Visible spectrophotometry (UV-Vis), photoluminescence (PL) spectra and fourier transform infrared spectroscopy (FTIR). Nanospherical balls revealing anatase and rutile crystal structures at (101) and (110) planes respectively were observed. Agglomerations of chain-like small particles manifested in Debye-Scherrer’s rings were evident from the TEM and SAED patterns. EDX spectra confirmed the deposition of the major elements: Ti and O. High transmittance of about 80% with a band gap energy range of 3.41-3.60 eV was obtained from the optical properties. Emission peaks arising from the PL spectra gave information on the charge transport and recombination rates occurring at the TiO2 nanoparticles while FTIR studies revealed the chemical vibrational bonds of the deposited TiO2 NPs. The obtained results show the deposited nanoparticles are suitable for solar cell applications.
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- Authors: Nkele, Agnes C. , Chime, Ugochi K. , Asogwa, Leonard , Nwanya, Assumpta C. , Nwankwo, Uba , Ukoba, K. , Jen, T. C. , Maaza, M. , Ezema, Fabian I.
- Date: 2019
- Subjects: SILAR , Titanium dioxide , Nanoparticles
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/404406 , uj:33913 , Citation: Nkele, A.C. et al. 2019. A study on Titanium Dioxide Nanoparticles synthesized from Titanium Isopropoxide under Silar-Induced Gel Method : transition from Anatase to Rutile structure.
- Description: Abstract: Successive ionic layer adsorption and reaction (SILAR) method was adopted in synthesizing titanium dioxide nanoparticles at various temperatures so as to investigate their morphological, structural, elemental, optical, chemical bond and photoluminescence properties. The as-prepared nanoparticles were characterized with scanning electron microscopy (SEM), X-ray diffractometry (XRD), transmission electron microscopy (TEM), selected area electron diffractometer (SAED), energy dispersive x-ray spectroscopy (EDX), UV-Visible spectrophotometry (UV-Vis), photoluminescence (PL) spectra and fourier transform infrared spectroscopy (FTIR). Nanospherical balls revealing anatase and rutile crystal structures at (101) and (110) planes respectively were observed. Agglomerations of chain-like small particles manifested in Debye-Scherrer’s rings were evident from the TEM and SAED patterns. EDX spectra confirmed the deposition of the major elements: Ti and O. High transmittance of about 80% with a band gap energy range of 3.41-3.60 eV was obtained from the optical properties. Emission peaks arising from the PL spectra gave information on the charge transport and recombination rates occurring at the TiO2 nanoparticles while FTIR studies revealed the chemical vibrational bonds of the deposited TiO2 NPs. The obtained results show the deposited nanoparticles are suitable for solar cell applications.
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Nanostructured TIO₂ based materials for the photocatalytic degradation of emerging organic pollutants from aqueous solution
- Authors: Sambaza, Shepherd Sundayi
- Date: 2019
- Subjects: Nanostructured materials , Titanium dioxide , Photocatalysis , Sewage - Purification
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/401572 , uj:33568
- Description: Abstract : Water is regarded as the most vital of natural resources for the sustainability of life, yet freshwater systems are directly threatened by pollution. Among the many pollutants are organic emerging pollutants such as synthetic chemicals and pharmaceuticals. Bisphenol A (BPA) and ibuprofen are examples of such a synthetic organic compounds. Current wastewater treatment technologies such as membrane technology, chemical treatment and biodegradation are not always efficient in removing toxic emerging organic pollutants. This is because they were not specifically designed to remove these contaminants. Photocatalysis on the other hand, has shown great potential to remove toxic emerging pollutants from the environment. Over the years, TiO2 catalyst has been used widely for water remediation applications. Surface modification of TiO2 is necessary to extend its use in the visible region of the solar spectrum and to reduce the inherent fast recombination rate of charges. Polyaniline (PANI)-wrapped TiO2 nanorods (PANI-TiO2), obtained through the oxidative polymerization of aniline at the surface of hydrothermally pre-synthesized TiO2 nanorods, were evaluated as photocatalysts for the degradation of BPA. Fourier-transform infrared spectroscopy (FTIR) analysis revealed the successful incorporation of PANI into TiO2 by the appearance of peaks at 1577 cm-1 and 1502 cm-1 that are due to the C=C and C=N stretch of the benzoid and quinoid. Brunauer- Emmett-Teller (BET) analysis revealed the presence of mesoporous material in PANI-TiO2. Transmission electron microscopy (TEM) analysis showed that TiO2 nanorods with different diameters were synthesized. The TEM analysis showed that a thin layer of PANI wrapped the TiO2 nanorods. X-ray diffraction (XRD) and Raman spectroscopy revealed that anatase phase TiO2 was synthesized with typical Raman vii vibration peaks at 637 cm-1, 514 cm-1, 396 cm-1, and 195 cm-1. X-ray Photon Spectroscopy (XPS) survey scan of the PANI-TiO2 nanocomposite revealed the presence of C, O, Ti, and N. Photocatalytic activity evaluation under UV radiation through the effect of key parameters, including, pH, contact time, dosage and initial concentration of BPA was carried out in batch studies. Within 80 min, 99.7% of 5 ppm BPA was attained using 0.2 g/L PANI-TiO2 photocatalyst at pH 10. PANI-TiO2 showed a better performance than as-synthesized TiO2 with a rate constant of 4.46 x 10-2 min-1 compared to 2.18 x 10-2 min-1. Nitrate ions increased the rate of degradation of BPA whilst humic acid consistently inhibited the degradation of BPA. LC-MS analysis identified degradation products with m/z 213.1, 135.1 and 93.1. The PANI-TiO2 nanocomposite was reused up to five cycles with a removal of at least 80% in the fifth cycle. PANI capped WO3@TiO2 nanocomposite prepared through a three–stage synthetic route was evaluated for the degradation of ibuprofen under visible light. XRD analysis confirmed the anatase phase of TiO2 and monoclinic and orthorhombic WO3 crystalline structures were formed. The XRD analysis confirmed that the phases were not affected by wrapping in PANI.TEM analysis confirmed that TiO2 nanorods were synthesized with different diameters. TEM analysis showed that a WO3@TiO2 heterojunction was formed. A PANI layer was wrapping the heterojunction was observed. Photoluminescence analysis revealed that pairing TiO2 and WO3 resulted in improved charge separation. The charge separation was further improved by wrapping the heterojunction in a PANI matrix. DRS calculations showed that pairing TiO2 with WO3 extended the band edge to about 420 nm thus facilitating the use of the nanocomposite in the visible region of the solar spectrum. XPS analysis revealed viii the presence of W, C, O, Ti, N, and their corresponding photo electron peaks were found to be W4f, W4d, C1s, O 1s, N1s, and Ti 2p. The degradation of ibuprofen was influenced by pH with maximum degradation observed at pH 9. The degradation conformed to the Langmuir-Hinshelwood kinetic model. The rate constant, K for the degradation of ibuprofen by WO3@TiO2 and PANI/WO3@TiO2 was 2.59 x 10-2 and 3.5 x 10-2 respectively that were significantly higher than that of pristine TiO2, which was 1.92 x10-2... , Ph.D. (Chemistry)
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- Authors: Sambaza, Shepherd Sundayi
- Date: 2019
- Subjects: Nanostructured materials , Titanium dioxide , Photocatalysis , Sewage - Purification
- Language: English
- Type: Doctoral (Thesis)
- Identifier: http://hdl.handle.net/10210/401572 , uj:33568
- Description: Abstract : Water is regarded as the most vital of natural resources for the sustainability of life, yet freshwater systems are directly threatened by pollution. Among the many pollutants are organic emerging pollutants such as synthetic chemicals and pharmaceuticals. Bisphenol A (BPA) and ibuprofen are examples of such a synthetic organic compounds. Current wastewater treatment technologies such as membrane technology, chemical treatment and biodegradation are not always efficient in removing toxic emerging organic pollutants. This is because they were not specifically designed to remove these contaminants. Photocatalysis on the other hand, has shown great potential to remove toxic emerging pollutants from the environment. Over the years, TiO2 catalyst has been used widely for water remediation applications. Surface modification of TiO2 is necessary to extend its use in the visible region of the solar spectrum and to reduce the inherent fast recombination rate of charges. Polyaniline (PANI)-wrapped TiO2 nanorods (PANI-TiO2), obtained through the oxidative polymerization of aniline at the surface of hydrothermally pre-synthesized TiO2 nanorods, were evaluated as photocatalysts for the degradation of BPA. Fourier-transform infrared spectroscopy (FTIR) analysis revealed the successful incorporation of PANI into TiO2 by the appearance of peaks at 1577 cm-1 and 1502 cm-1 that are due to the C=C and C=N stretch of the benzoid and quinoid. Brunauer- Emmett-Teller (BET) analysis revealed the presence of mesoporous material in PANI-TiO2. Transmission electron microscopy (TEM) analysis showed that TiO2 nanorods with different diameters were synthesized. The TEM analysis showed that a thin layer of PANI wrapped the TiO2 nanorods. X-ray diffraction (XRD) and Raman spectroscopy revealed that anatase phase TiO2 was synthesized with typical Raman vii vibration peaks at 637 cm-1, 514 cm-1, 396 cm-1, and 195 cm-1. X-ray Photon Spectroscopy (XPS) survey scan of the PANI-TiO2 nanocomposite revealed the presence of C, O, Ti, and N. Photocatalytic activity evaluation under UV radiation through the effect of key parameters, including, pH, contact time, dosage and initial concentration of BPA was carried out in batch studies. Within 80 min, 99.7% of 5 ppm BPA was attained using 0.2 g/L PANI-TiO2 photocatalyst at pH 10. PANI-TiO2 showed a better performance than as-synthesized TiO2 with a rate constant of 4.46 x 10-2 min-1 compared to 2.18 x 10-2 min-1. Nitrate ions increased the rate of degradation of BPA whilst humic acid consistently inhibited the degradation of BPA. LC-MS analysis identified degradation products with m/z 213.1, 135.1 and 93.1. The PANI-TiO2 nanocomposite was reused up to five cycles with a removal of at least 80% in the fifth cycle. PANI capped WO3@TiO2 nanocomposite prepared through a three–stage synthetic route was evaluated for the degradation of ibuprofen under visible light. XRD analysis confirmed the anatase phase of TiO2 and monoclinic and orthorhombic WO3 crystalline structures were formed. The XRD analysis confirmed that the phases were not affected by wrapping in PANI.TEM analysis confirmed that TiO2 nanorods were synthesized with different diameters. TEM analysis showed that a WO3@TiO2 heterojunction was formed. A PANI layer was wrapping the heterojunction was observed. Photoluminescence analysis revealed that pairing TiO2 and WO3 resulted in improved charge separation. The charge separation was further improved by wrapping the heterojunction in a PANI matrix. DRS calculations showed that pairing TiO2 with WO3 extended the band edge to about 420 nm thus facilitating the use of the nanocomposite in the visible region of the solar spectrum. XPS analysis revealed viii the presence of W, C, O, Ti, N, and their corresponding photo electron peaks were found to be W4f, W4d, C1s, O 1s, N1s, and Ti 2p. The degradation of ibuprofen was influenced by pH with maximum degradation observed at pH 9. The degradation conformed to the Langmuir-Hinshelwood kinetic model. The rate constant, K for the degradation of ibuprofen by WO3@TiO2 and PANI/WO3@TiO2 was 2.59 x 10-2 and 3.5 x 10-2 respectively that were significantly higher than that of pristine TiO2, which was 1.92 x10-2... , Ph.D. (Chemistry)
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Visible light photocatalytic degradation of pollutants in surface water, Limpopo, South Africa
- Authors: Ntobeng, Mahubedu Khutso
- Date: 2021
- Subjects: Water - Purification - Photocatalysis , Titanium dioxide
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/481968 , uj:43688
- Description: Abstract: A novel silver and vanadium co-doped titanium dioxide (Ag, V-TiO2) photocatalyst was achieved by a simple sol-gel hydrothermal method. The co-doped Ag, V-TiO2 photocatalyst exhibited high photocatalytic activity as compared to synthesised titanium dioxide (TiO2), silver doped titanium dioxide (Ag-TiO2) and Vanadium dope titanium dioxide (V-TiO2). The co-doped Ag, V-TiO2 illustrated a shift in the absorption edge, enhancing the visible light absorption capacity. The optical absorption of co-doped Ag, V-TiO2 achieved a reduced band gap energy (Eg) of 2.2eV as compared to Ag-TiO2 (2.8eV) and V-TiO2 (2.3eV), while TiO2 obtained a band gap energy of 2.9eV. The codoped photocatalyst inherited morphological and structural compositions that depicted the lattice fringes for both anatase and rutile in its crystalline phase. This analysis was in good agreement with results obtained by X-ray diffraction (XRD) characterisation techniques. Co-doped Ag, V-TiO2 showed excellent photocatalytic abilities under visible light irradiation. The degradation of Methylene blue (MB) was achieved within the first 15min. The kinetic study for the degradation of (MB) followed the pseudo-first order reaction. More interestingly, it was found that the photocatalytic degradation performance had a direct relation with the intensity plane ratio corresponding to [101] / [110]. The effects of co-doping showed a shift in spectrum to the visible light region. This was evident in the study of binding energies presented by X-ray photoelectron spectroscopy (XPS). Thus, the effects of co-doping TiO2 showed achieving well desirable reduction in the band gap energy and enhancements in the photocatalytic activity, reporting excellent removal rates of 99.33%. The evaluation of photocatalytic degradation of pollutants in water from River water in Limpopo (Mathibeng) and Mpumalanga Witbank (Ezinabeni) gave a clear indication that the synthesized Ag, V co-doped TiO2 photocatalyst was effective in removing nitrate, nitrites, humic substance, aromatics, Trihalomethanes (THM) and organic concentration. Furthermore, the GC-MS analysis of the water samples proved the organic pollutants removal with a removal efficiency of 77.84%. These finding open up a solution for the treatment of surface and river water where the concentration of pollutants are low. , M.Ing. (Mechanical Engineering)
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- Authors: Ntobeng, Mahubedu Khutso
- Date: 2021
- Subjects: Water - Purification - Photocatalysis , Titanium dioxide
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/481968 , uj:43688
- Description: Abstract: A novel silver and vanadium co-doped titanium dioxide (Ag, V-TiO2) photocatalyst was achieved by a simple sol-gel hydrothermal method. The co-doped Ag, V-TiO2 photocatalyst exhibited high photocatalytic activity as compared to synthesised titanium dioxide (TiO2), silver doped titanium dioxide (Ag-TiO2) and Vanadium dope titanium dioxide (V-TiO2). The co-doped Ag, V-TiO2 illustrated a shift in the absorption edge, enhancing the visible light absorption capacity. The optical absorption of co-doped Ag, V-TiO2 achieved a reduced band gap energy (Eg) of 2.2eV as compared to Ag-TiO2 (2.8eV) and V-TiO2 (2.3eV), while TiO2 obtained a band gap energy of 2.9eV. The codoped photocatalyst inherited morphological and structural compositions that depicted the lattice fringes for both anatase and rutile in its crystalline phase. This analysis was in good agreement with results obtained by X-ray diffraction (XRD) characterisation techniques. Co-doped Ag, V-TiO2 showed excellent photocatalytic abilities under visible light irradiation. The degradation of Methylene blue (MB) was achieved within the first 15min. The kinetic study for the degradation of (MB) followed the pseudo-first order reaction. More interestingly, it was found that the photocatalytic degradation performance had a direct relation with the intensity plane ratio corresponding to [101] / [110]. The effects of co-doping showed a shift in spectrum to the visible light region. This was evident in the study of binding energies presented by X-ray photoelectron spectroscopy (XPS). Thus, the effects of co-doping TiO2 showed achieving well desirable reduction in the band gap energy and enhancements in the photocatalytic activity, reporting excellent removal rates of 99.33%. The evaluation of photocatalytic degradation of pollutants in water from River water in Limpopo (Mathibeng) and Mpumalanga Witbank (Ezinabeni) gave a clear indication that the synthesized Ag, V co-doped TiO2 photocatalyst was effective in removing nitrate, nitrites, humic substance, aromatics, Trihalomethanes (THM) and organic concentration. Furthermore, the GC-MS analysis of the water samples proved the organic pollutants removal with a removal efficiency of 77.84%. These finding open up a solution for the treatment of surface and river water where the concentration of pollutants are low. , M.Ing. (Mechanical Engineering)
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