Development of a visible light active, photo-catalytic and antimicrobial nanocomposite of titanium dioxide and silicon dioxide for water treatment
- Authors: Mungondori, Henry Heroe
- Date: 2012
- Subjects: Titanium dioxide , Silica , Catalysis , Nanocomposites (Materials) , Water -- Purification
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11335 , http://hdl.handle.net/10353/471 , Titanium dioxide , Silica , Catalysis , Nanocomposites (Materials) , Water -- Purification
- Description: The aim of this study was to prepare composite materials based on titanium dioxide (TiO2) and silicon dioxide (SiO2), and to evaluate their photo-catalytic and antimicrobial properties. Carbon and nitrogen doped TiO2nano-particles were prepared via a sol gel synthesis, which is a simple hydrolysis and condensation technique. In situ doping was carried out using glucose and urea as carbon and nitrogen sources respectively. Doping increased the spectral response of titanium dioxide photo-catalyst, allowing it to utilise the visible region which is much wider than the UV region (about 40 % of the solar spectrum), thus making it a more efficient photo-catalyst. The carbon and nitrogen doped TiO2-SiO2nano-particles were immobilized on glass support material to allow for easy separation of the spent photo-catalyst after the photo-degradation process. Tetraethyl orthosilicate (TEOS) was employed as both a binder and precursor for silicon dioxide. A mixture of TiO2 and TEOS in a 1:1 ratio was allowed to polymerize on a glass support which had been treated with hydrofluoric acid to introduce OH groups. The prepared photo-catalytic material was characterized by FT-IR, XRD, DRS, TEM, EDX, and BET analyses. Carbon was found to be more effective as a dopant than nitrogen. It brought about a band gap reduction of 0.30 eV and a BET surface area of 95.4 m2g-1 on the photo-catalyst as compared to a gap reduction of 0.2 eV and surface area of 52.2 m2g-1 for nitrogen doped TiO2. On the other hand, introduction of SiO2 allowed utilization of visible light by the TiO2-SiO2 nano-composite leading to an improved rate of photo-degradation of both methyl orange and phenol red. However, the immobilization of TiO2 on support material made it less effective towards inactivation of E. coli ATCC 25922 bacterial cells when compared to powdered TiO2 which was able to inactivate about 98 % of the bacterial cells within an hour of treatment.
- Full Text:
- Date Issued: 2012
- Authors: Mungondori, Henry Heroe
- Date: 2012
- Subjects: Titanium dioxide , Silica , Catalysis , Nanocomposites (Materials) , Water -- Purification
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11335 , http://hdl.handle.net/10353/471 , Titanium dioxide , Silica , Catalysis , Nanocomposites (Materials) , Water -- Purification
- Description: The aim of this study was to prepare composite materials based on titanium dioxide (TiO2) and silicon dioxide (SiO2), and to evaluate their photo-catalytic and antimicrobial properties. Carbon and nitrogen doped TiO2nano-particles were prepared via a sol gel synthesis, which is a simple hydrolysis and condensation technique. In situ doping was carried out using glucose and urea as carbon and nitrogen sources respectively. Doping increased the spectral response of titanium dioxide photo-catalyst, allowing it to utilise the visible region which is much wider than the UV region (about 40 % of the solar spectrum), thus making it a more efficient photo-catalyst. The carbon and nitrogen doped TiO2-SiO2nano-particles were immobilized on glass support material to allow for easy separation of the spent photo-catalyst after the photo-degradation process. Tetraethyl orthosilicate (TEOS) was employed as both a binder and precursor for silicon dioxide. A mixture of TiO2 and TEOS in a 1:1 ratio was allowed to polymerize on a glass support which had been treated with hydrofluoric acid to introduce OH groups. The prepared photo-catalytic material was characterized by FT-IR, XRD, DRS, TEM, EDX, and BET analyses. Carbon was found to be more effective as a dopant than nitrogen. It brought about a band gap reduction of 0.30 eV and a BET surface area of 95.4 m2g-1 on the photo-catalyst as compared to a gap reduction of 0.2 eV and surface area of 52.2 m2g-1 for nitrogen doped TiO2. On the other hand, introduction of SiO2 allowed utilization of visible light by the TiO2-SiO2 nano-composite leading to an improved rate of photo-degradation of both methyl orange and phenol red. However, the immobilization of TiO2 on support material made it less effective towards inactivation of E. coli ATCC 25922 bacterial cells when compared to powdered TiO2 which was able to inactivate about 98 % of the bacterial cells within an hour of treatment.
- Full Text:
- Date Issued: 2012
Preparation of photocatalytic TiO₂ nanoparticles immobilized on carbon nanofibres for water purification
- Authors: Nyamukamba, Pardon
- Date: 2011
- Subjects: Water -- Purification , Titanium alloys -- Industrial applications , Titanium , Nanoparticles , Drinking water -- Purification , Drinking water -- Contamination
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11330 , http://hdl.handle.net/10353/367 , Water -- Purification , Titanium alloys -- Industrial applications , Titanium , Nanoparticles , Drinking water -- Purification , Drinking water -- Contamination
- Description: Titanium dioxide nanoparticles were prepared using the sol-gel process. The effect of temperature and precursor concentration on particle size was investigated. The optimum conditions were then used to prepare carbon and nitrogen doped titanium dioxide (TiO2) nanoparticles. Doping was done to reduce band gap of the nanoparticles in order to utilize visible light in the photocatalytic degradation of organic compounds. A significant shift of the absorption edge to a longer wavelength (lower energy) from 420 nm to 456 nm and 420 nm to 428 nm was observed for the carbon doped and nitrogen doped TiO2 respectively. In this study, the prepared TiO2 photocatalyst was immobilized on carbon nanofibres to allow isolation and reuse of catalyst. The photocatalytic activity of the catalyst was tested using methyl orange as a model pollutant and was based on the decolourization of the dye as it was degraded. The doped TiO2 exhibited higher photocatalytic activity than the undoped TiO2. The materials prepared were characterized by XRD, TEM, SEM, FT-IR, DSC and TGA while the doped TiO2 was characterized by XPS, ESR and Raman Spectroscopy.
- Full Text:
- Date Issued: 2011
- Authors: Nyamukamba, Pardon
- Date: 2011
- Subjects: Water -- Purification , Titanium alloys -- Industrial applications , Titanium , Nanoparticles , Drinking water -- Purification , Drinking water -- Contamination
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11330 , http://hdl.handle.net/10353/367 , Water -- Purification , Titanium alloys -- Industrial applications , Titanium , Nanoparticles , Drinking water -- Purification , Drinking water -- Contamination
- Description: Titanium dioxide nanoparticles were prepared using the sol-gel process. The effect of temperature and precursor concentration on particle size was investigated. The optimum conditions were then used to prepare carbon and nitrogen doped titanium dioxide (TiO2) nanoparticles. Doping was done to reduce band gap of the nanoparticles in order to utilize visible light in the photocatalytic degradation of organic compounds. A significant shift of the absorption edge to a longer wavelength (lower energy) from 420 nm to 456 nm and 420 nm to 428 nm was observed for the carbon doped and nitrogen doped TiO2 respectively. In this study, the prepared TiO2 photocatalyst was immobilized on carbon nanofibres to allow isolation and reuse of catalyst. The photocatalytic activity of the catalyst was tested using methyl orange as a model pollutant and was based on the decolourization of the dye as it was degraded. The doped TiO2 exhibited higher photocatalytic activity than the undoped TiO2. The materials prepared were characterized by XRD, TEM, SEM, FT-IR, DSC and TGA while the doped TiO2 was characterized by XPS, ESR and Raman Spectroscopy.
- Full Text:
- Date Issued: 2011
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