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Application of photocatalysis to the treatment of complex industrial aqueous effluent in a pilot-scale bubble column reactorQazaq, Amjad Saleh Hussein, Chemical Sciences & Engineering, Faculty of Engineering, UNSW January 2009 (has links)
In this study, the photocatalytic mineralization of the industrial dump-site leachate was evaluated using an internally-irradiated 18-Litre pilot-scale aerated annular bubble column photoreactor. The study includes evaluating the effect of catalyst loading, leachate initial concentration, initial solution pH, light intensity and oxygen partial pressure. The reaction runs were performed over a 48-hours period at room temperature and atmospheric pressure. Titanium catalyst loading was optimized to be 3 gL-1 where the reaction rate constant 20x10-6 mol L-1 min-1.Beyond this dosage, the effect of light scattering by the catalyst particles were noticed on dropping the degradation rate. Moreover, at high catalyst loading, particles aggregates reduce the interfacial area between the reaction solution and the photocatalyst resulting in significant reduction in the number of active sites on the catalyst surface. It is also noticed that when the initial leachate concentration is high, the number of the active sites are decreased because of their competitive adsorption on the TiO2 particles; while on the other hand, during the light intensity illumination period, the OH radicals formed on the catalyst surface are remaining constant as evidenced by constant hydroxyl production rate. Thus, the reactive O2 attacking the contaminants molecules decrease and simultaneously the overall photodegradation efficiency also decrease dramatically. The plot of the apparent reaction rate constant versus the initial leachate concentration exhibits almost a quadratic behaviour which has an optimum value at concentration of 50 mM. Finally, it was found that the degradation rate constant increased with O2 partial pressure until a maximum was obtained around 50% O2/N2 of gas feed composition. The drop in the rate beyond 50% can be explained by the fact that the dissolved oxygen molecular oxygen is strongly electrophilic and thus increasing the dissolved oxygen content probably reduced electron-hole recombination rate and hence the system was able to maintain favourable charge balance necessary for the photocatalytic-redox process. Moreover, in the presence of excess O2, the photocatalyst surface may become highly hydroxylated to the point of inhibiting the adsorption of organic species causing decrease in the degradation rate. Effect of upflow co-current and counter current continuous operation mode were performed in the 18-litre bubble column photoreactor for the photooxidation degradation tratment of the dump-site landfill leachate. The best situation is liquid flow rate at 800 mL min-1 and total gas flow rate at 5 Lmin-1 for the counter current operation, while for the up-flow co-current operation, the best situation is liquid flow rate at 600 mL min-1 and total gas flow rate at 5 Lmin-1
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Σύνθεση και χαρακτηρισμός δυο νέων νανοσύνθετων αλλουσίτη-TiO2Ντζάλα, Σταυρούλα 09 October 2014 (has links)
Στην παρούσα πτυχιακή παρασκευάστηκαν νανοσύνθετα υλικά TiO290-HALL10 και
TiO280-HALL20 ώστε να εφαρµοστούν στην φωτοκαταλυτική αποδόµηση αερίων
ρύπων.
Τα νανοσύνθετα παρασκευάστηκαν µε τη µέθοδο διασποράς-επικάθισης του TiO2 και
στους επιµήκεις κρυστάλλους του Αλλουσίτη.Η κρυσταλλική µορφή του TiO2 που
συντέθηκε ήταν ο ανατάσης.
Εφαρµόστηκαν οι παρακάτω τεχνικές:περιθλασιµετρία ακτίνων X(XRD), υπέρυθρη
φασµατοσκοπία µετασχηµατισµού κατά Fourier(ATR-FTIR), ηλεκτρονική
µικροσκοπία σάρωσης(SEM),προσδιορισµός µεγέθους και κατανοµής πόρων καθώς
και ειδικής επιφάνειας.
Tα νανοσύνθετα υλικά λόγω των ιδιοτήτων τους φαίνεται να είναι αποτελεσµατικά
στην εφαρµογή τους στους αέριους ρύπους και έτσι µπορούν να χρησιµοποιηθούν και
στις οργανικές πτητικές ενώσεις. / In this study were prepared nanocomposites TiO290-HALL10 and TiO280-HALL20
order to be applied in several environmental applications.
The samples were prepared by dispersing TiO2 nanoparticles on the microfabers of
alloysite. The crystal form of TiO2 that was synthesized was anatase.
The nanocomposites were characterized using the following techniques:X-ray
diffraction(XRD), scanning electron microscopy(SEM), attenuated total reflection
using Fourier transform infrared spectroscopy (ATR-FTIR) and N2 surface analysis
by BET.
The nanocomposites due to their characteristics showing to be effective in
decomposing air pollutants and can be used in volatile organic compounds.
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Nanostructured Photocatalysts for the Destruction of StyreneMr Chun Siong Melvin Lim Unknown Date (has links)
No description available.
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Argamassa autolimpante para revestimento de fachadas : o efeito das propriedades fotocatalíticas do dióxido de titânio (TiO2) / Self-cleaning mortar to covering of facades : the effect of the photocatalytic properties of the titanium dioxide (TiO2)Austria, Gabriela Cortes January 2015 (has links)
As fachadas das edificações, ao longo de sua vida útil, sofrem degradação devido a ataques de agentes químicos e à deposição de partículas na sua superfície. Como consequências, há perdas no desempenho de seus materiais e a desfiguração estética das fachadas por meio de manchas, implicando em ações de reparo que envolvem custos elevados. Os produtos atualmente disponíveis no mercado brasileiro com objetivo de evitar o manchamento de fachadas têm baixa eficiência, sendo que os principais deles adotam a técnica do pós-tratamento com hidrofugantes, os quais geralmente alteram a coloração do substrato e podem ser a origem de novas patologias. Usufruindo de novas tecnologias, o dióxido de titânio (TiO2) apresenta-se como material nanométrico amplamente estudado na área científica, sendo potencialmente utilizado como fotocalisador. O presente trabalho verificou a possibilidade de obtenção de superfícies autolimpantes a partir da adição de TiO2 em revestimentos de argamassa branca. Estas, a partir de propriedades fotocatalíticas do TiO2 podem ser tornar autolimpantes sob ação da radiação solar (UV) e da chuva. Foram confeccionadas argamassas de traço 1:2 e 1:3, com adições de 0%, 5% e 10% de TiO2 em relação à massa de cimento, com consistência fixa. As amostras foram aspergidas com diferentes agentes manchantes: azul de metileno, particulado de poluição, produto de corrosão, pichação; e sem manchamento (referência). Após, estas amostras foram expostas nas condições ambientais da cidade de Porto Alegre. Ao longo de 84 dias, foram realizadas leituras com espectrofotômetro portátil para avaliar o efeito autolimpante. Também foram verificadas as propriedades físico-mecânicas das argamassas. Os resultados apontaram que argamassas com adição de TiO2 necessitaram maior quantidade de água, apresentaram maior densidade no estado fresco e menor teor de ar incorporado. Ainda, a resistência à compressão foi elevada para o traço mais rico (1:2) e mantida constante para o traço pobre (1:3). Além disso, se mostraram mais claras/brancas quanto maior a porcentagem de adição. O efeito autolimpante pode ser percebido mais facilmente na mancha de azul de metileno, porém, a limpeza ocorreu tanto em argamassas com adição de TiO2, quanto em argamassas sem a adição. Em manchas que geraram uma película sobre a placa, o efeito autolimpante foi dificultado. / The facades of buildings, during their lifespan, suffer degradation due to attacks of chemical agents and due to deposition of particles on their surface. As consequences, there are losses on the performance of their materials and aesthetics disfiguration of the facades by stains, implying repairing actions involving high costs. The products available nowadays on the brasilian market with the purpose to avoid the staining of the facades have low efficiency, and the main products between them adopt the technique of post-treatment with hydrophobing, which generally modify the colour of the substrate and which can originate new pathologies. Taking advantage of new technologies, the titanium dioxide (TiO2) appears as a nanometric material widely studied in the scientific area, being pottentialy used as photocatalyser. The present work has verified the possibility of obtention of self-cleaning surfaces after addition of TiO2 in white mortar coverings. Those, from photocatalyser properties of the TiO2 can become self-cleaning under the action of solar radiation (UV) and rain. There were prepared mortars of trace 1:2 and 1:3, with additions of 0%, 5% and 10% of TiO2 in relation of the cement weight, with steady consistency. The samples were sprinkled with different staining agents: methylene blue, pollution particulates, corrosion product, graffiti; and without stains (reference). After that, these samples were exposed to the ambiental conditions of the city of Porto Alegre. Through 84 days, scannings were made with portable spectrophotometer to evaluate the self-cleaning effect. The physicalmechanical properties of the mortars were also verified. The results point out that mortars with addition of TiO2 required a bigger amount of water, they presented bigger density in the fresh state and smaller contents of incorporated air. Besides, the compression resistance was high to the richest trace (1:2) and remained constant to the poor trace (1:3). Moreover, they have showed themselves more clear/white as bigger was the percentage of addition. The self-cleaning effect can be more easily noticed on the methylene blue stain, however, the cleaning occurred both in mortars with addition of TiO2 and in mortars without the addition. In stains which generate a film above the plate, the self-cleaning effect was hampered.
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Argamassa autolimpante para revestimento de fachadas : o efeito das propriedades fotocatalíticas do dióxido de titânio (TiO2) / Self-cleaning mortar to covering of facades : the effect of the photocatalytic properties of the titanium dioxide (TiO2)Austria, Gabriela Cortes January 2015 (has links)
As fachadas das edificações, ao longo de sua vida útil, sofrem degradação devido a ataques de agentes químicos e à deposição de partículas na sua superfície. Como consequências, há perdas no desempenho de seus materiais e a desfiguração estética das fachadas por meio de manchas, implicando em ações de reparo que envolvem custos elevados. Os produtos atualmente disponíveis no mercado brasileiro com objetivo de evitar o manchamento de fachadas têm baixa eficiência, sendo que os principais deles adotam a técnica do pós-tratamento com hidrofugantes, os quais geralmente alteram a coloração do substrato e podem ser a origem de novas patologias. Usufruindo de novas tecnologias, o dióxido de titânio (TiO2) apresenta-se como material nanométrico amplamente estudado na área científica, sendo potencialmente utilizado como fotocalisador. O presente trabalho verificou a possibilidade de obtenção de superfícies autolimpantes a partir da adição de TiO2 em revestimentos de argamassa branca. Estas, a partir de propriedades fotocatalíticas do TiO2 podem ser tornar autolimpantes sob ação da radiação solar (UV) e da chuva. Foram confeccionadas argamassas de traço 1:2 e 1:3, com adições de 0%, 5% e 10% de TiO2 em relação à massa de cimento, com consistência fixa. As amostras foram aspergidas com diferentes agentes manchantes: azul de metileno, particulado de poluição, produto de corrosão, pichação; e sem manchamento (referência). Após, estas amostras foram expostas nas condições ambientais da cidade de Porto Alegre. Ao longo de 84 dias, foram realizadas leituras com espectrofotômetro portátil para avaliar o efeito autolimpante. Também foram verificadas as propriedades físico-mecânicas das argamassas. Os resultados apontaram que argamassas com adição de TiO2 necessitaram maior quantidade de água, apresentaram maior densidade no estado fresco e menor teor de ar incorporado. Ainda, a resistência à compressão foi elevada para o traço mais rico (1:2) e mantida constante para o traço pobre (1:3). Além disso, se mostraram mais claras/brancas quanto maior a porcentagem de adição. O efeito autolimpante pode ser percebido mais facilmente na mancha de azul de metileno, porém, a limpeza ocorreu tanto em argamassas com adição de TiO2, quanto em argamassas sem a adição. Em manchas que geraram uma película sobre a placa, o efeito autolimpante foi dificultado. / The facades of buildings, during their lifespan, suffer degradation due to attacks of chemical agents and due to deposition of particles on their surface. As consequences, there are losses on the performance of their materials and aesthetics disfiguration of the facades by stains, implying repairing actions involving high costs. The products available nowadays on the brasilian market with the purpose to avoid the staining of the facades have low efficiency, and the main products between them adopt the technique of post-treatment with hydrophobing, which generally modify the colour of the substrate and which can originate new pathologies. Taking advantage of new technologies, the titanium dioxide (TiO2) appears as a nanometric material widely studied in the scientific area, being pottentialy used as photocatalyser. The present work has verified the possibility of obtention of self-cleaning surfaces after addition of TiO2 in white mortar coverings. Those, from photocatalyser properties of the TiO2 can become self-cleaning under the action of solar radiation (UV) and rain. There were prepared mortars of trace 1:2 and 1:3, with additions of 0%, 5% and 10% of TiO2 in relation of the cement weight, with steady consistency. The samples were sprinkled with different staining agents: methylene blue, pollution particulates, corrosion product, graffiti; and without stains (reference). After that, these samples were exposed to the ambiental conditions of the city of Porto Alegre. Through 84 days, scannings were made with portable spectrophotometer to evaluate the self-cleaning effect. The physicalmechanical properties of the mortars were also verified. The results point out that mortars with addition of TiO2 required a bigger amount of water, they presented bigger density in the fresh state and smaller contents of incorporated air. Besides, the compression resistance was high to the richest trace (1:2) and remained constant to the poor trace (1:3). Moreover, they have showed themselves more clear/white as bigger was the percentage of addition. The self-cleaning effect can be more easily noticed on the methylene blue stain, however, the cleaning occurred both in mortars with addition of TiO2 and in mortars without the addition. In stains which generate a film above the plate, the self-cleaning effect was hampered.
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Reduced graphene oxide nanoparticle hybrids and their assembly for lithium-ion battery anodesModarres, Mohammad Hadi January 2018 (has links)
Lithium-ion batteries (LIBs) are an integral part of consumer electronic devices and electric vehicles. There is a growing need for LIBs with higher capacity, rate performance and cycling stability. At the anode electrode these challenges are being addressed for instance by utilising materials with higher theoretical capacity compared to graphite (372 mAh/g) or by optimising the morphology of materials through nanostructuring of the electrode. In this thesis the former is investigated by synthesising a reduced graphene oxide (rGO) tin sulphide (SnS2) hybrid, and the latter by self-assembly of rGO sodium titanate and rGO titanium dioxide (TiO2) nanorods. In Chapter 2, SnS2 is investigated due to its high theoretical capacity as an anode material (645 mAh/g), low cost and environmental benignity. SnS2 nanoparticles were grown directly on rGO sheets which provide a conductive framework and limit the detachment of tin particles which undergo large volume changes during alloying reactions. However, a fast decrease in capacity was observed. Post-mortem analysis of the electrodes showed that rGO becomes irreversibly passivated suggesting that additional measures to retain effective charge transport between the low weight percent conductive additive and the active phase during cycling are required. An alternative material system based on nanorods of intercalation materials (sodium titanate and TiO2) wrapped by rGO sheets was chosen to investigate self-assembly in anodes to address the low packing density of nanomaterials. A drop-casting method was used to align rGO-sodium titanate nanorods through evaporation driven self-assembly (Chapter 3) which relies on a combination of electrostatic repulsive forces originating from the rGO coating, and liquid crystal phase formation at high concentrations, facilitated by the high aspect ratio nanorods. As reference, non-aligned films were prepared by adjusting the pH of the nanorod dispersion. Freestanding aligned and non-aligned films were converted to rGO-TiO2 (Chapter 4). The volumetric capacity of the self-assembled films was double that of non-aligned films, and up to 4.5 times higher than traditional casted electrodes using the same material. Further, up to rates of 4 C, the self-assembled films outperformed the non-aligned films. These films showed no sign of capacity fading up to 1000 cycles, which together with post-mortem analysis confirms that these assembled structures are maintained during battery cycling.
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Argamassa autolimpante para revestimento de fachadas : o efeito das propriedades fotocatalíticas do dióxido de titânio (TiO2) / Self-cleaning mortar to covering of facades : the effect of the photocatalytic properties of the titanium dioxide (TiO2)Austria, Gabriela Cortes January 2015 (has links)
As fachadas das edificações, ao longo de sua vida útil, sofrem degradação devido a ataques de agentes químicos e à deposição de partículas na sua superfície. Como consequências, há perdas no desempenho de seus materiais e a desfiguração estética das fachadas por meio de manchas, implicando em ações de reparo que envolvem custos elevados. Os produtos atualmente disponíveis no mercado brasileiro com objetivo de evitar o manchamento de fachadas têm baixa eficiência, sendo que os principais deles adotam a técnica do pós-tratamento com hidrofugantes, os quais geralmente alteram a coloração do substrato e podem ser a origem de novas patologias. Usufruindo de novas tecnologias, o dióxido de titânio (TiO2) apresenta-se como material nanométrico amplamente estudado na área científica, sendo potencialmente utilizado como fotocalisador. O presente trabalho verificou a possibilidade de obtenção de superfícies autolimpantes a partir da adição de TiO2 em revestimentos de argamassa branca. Estas, a partir de propriedades fotocatalíticas do TiO2 podem ser tornar autolimpantes sob ação da radiação solar (UV) e da chuva. Foram confeccionadas argamassas de traço 1:2 e 1:3, com adições de 0%, 5% e 10% de TiO2 em relação à massa de cimento, com consistência fixa. As amostras foram aspergidas com diferentes agentes manchantes: azul de metileno, particulado de poluição, produto de corrosão, pichação; e sem manchamento (referência). Após, estas amostras foram expostas nas condições ambientais da cidade de Porto Alegre. Ao longo de 84 dias, foram realizadas leituras com espectrofotômetro portátil para avaliar o efeito autolimpante. Também foram verificadas as propriedades físico-mecânicas das argamassas. Os resultados apontaram que argamassas com adição de TiO2 necessitaram maior quantidade de água, apresentaram maior densidade no estado fresco e menor teor de ar incorporado. Ainda, a resistência à compressão foi elevada para o traço mais rico (1:2) e mantida constante para o traço pobre (1:3). Além disso, se mostraram mais claras/brancas quanto maior a porcentagem de adição. O efeito autolimpante pode ser percebido mais facilmente na mancha de azul de metileno, porém, a limpeza ocorreu tanto em argamassas com adição de TiO2, quanto em argamassas sem a adição. Em manchas que geraram uma película sobre a placa, o efeito autolimpante foi dificultado. / The facades of buildings, during their lifespan, suffer degradation due to attacks of chemical agents and due to deposition of particles on their surface. As consequences, there are losses on the performance of their materials and aesthetics disfiguration of the facades by stains, implying repairing actions involving high costs. The products available nowadays on the brasilian market with the purpose to avoid the staining of the facades have low efficiency, and the main products between them adopt the technique of post-treatment with hydrophobing, which generally modify the colour of the substrate and which can originate new pathologies. Taking advantage of new technologies, the titanium dioxide (TiO2) appears as a nanometric material widely studied in the scientific area, being pottentialy used as photocatalyser. The present work has verified the possibility of obtention of self-cleaning surfaces after addition of TiO2 in white mortar coverings. Those, from photocatalyser properties of the TiO2 can become self-cleaning under the action of solar radiation (UV) and rain. There were prepared mortars of trace 1:2 and 1:3, with additions of 0%, 5% and 10% of TiO2 in relation of the cement weight, with steady consistency. The samples were sprinkled with different staining agents: methylene blue, pollution particulates, corrosion product, graffiti; and without stains (reference). After that, these samples were exposed to the ambiental conditions of the city of Porto Alegre. Through 84 days, scannings were made with portable spectrophotometer to evaluate the self-cleaning effect. The physicalmechanical properties of the mortars were also verified. The results point out that mortars with addition of TiO2 required a bigger amount of water, they presented bigger density in the fresh state and smaller contents of incorporated air. Besides, the compression resistance was high to the richest trace (1:2) and remained constant to the poor trace (1:3). Moreover, they have showed themselves more clear/white as bigger was the percentage of addition. The self-cleaning effect can be more easily noticed on the methylene blue stain, however, the cleaning occurred both in mortars with addition of TiO2 and in mortars without the addition. In stains which generate a film above the plate, the self-cleaning effect was hampered.
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Correlação entre as propriedades fotocrômicas e atividade fotocatalítica dos óxidos de titânio e tungstênioSilva, Luana Góes Soares da January 2018 (has links)
O emprego de TiO2, na qualidade de semicondutor mais comumente utilizado em fotocatálise heterogênea adquire relevância, devido à sua eficiência na decomposição de poluentes da água, do ar, bactérias, células cancerígenas e na degradação de compostos orgânicos tóxicos. Este trabalho investigou a correlação entre as propriedades fotocrômicas e fotocatalíticas de fibras e dos filmes de TiO2, e de TiO2 dopados com H2WO4 e Na2WO4.2H2O. Para a síntese de fibras por electrospinning os reagentes utilizados foram: ácido acético glacial, propóxido de titânio, polivinilpirrolidona 10%, ácido túngstico e tungstato de sódio di hidratado. As fibras obtidas foram tratadas termicamente entre 650 ºC e 800 ºC, com patamar de 1 hora e taxa de aquecimento de 1,4 °C/min. Para obtenção dos filmes por spin-coater foram peparadas soluções contendo: 0,25 g de fibras tratadas entre 650 ºC e 800 ºC, etanol anidro, acetilacetona, Triton X-100 e polivinilbitiral. As amostras foram caracterizadas por difração de raios X (DRX), microscopia eletrônica de varredura (MEV) e de transmissão (MET), análise termogravimétrica (TGA) e termo-diferencial (ATD), espectroscopia de reflectância difusa (ERD), perfilometria, teoria Brunnauer Emmet e Teller (BET), ensaios de degradação de 125 mL de uma solução 20 ppm do corante alaranjado de metila e colorimetria através do sistema CIELa*b*. Os melhores resultados foram obtidos com as amostras deTiO2∕Na2WO4.2H2O. Estas amostras foram mais eficientes na mineralização do corante alaranjado de metila, pois 3 das 4 amostras sintetizadas degradaram aproximadamente 100% do corante e simultaneamente expressaram os maiores valores de reflectância, possivelmente devido a existência de uma sincronização entre as características químicas e físicas destes óxidos e a formação de defeitos pontuais (vacâncias) que ocupam posições atômicas de rede. / The use of TiO2 as the most commonly used semiconductor in heterogeneous photocatalysis becomes relevant because of its efficiency in the decomposition of pollutants from water, air, bacteria, cancer cells and the degradation of toxic organic compounds. This work investigated the correlation between the photocatalytic and photocatalytic properties of TiO2 and TiO2 fibers and TiO2 doped with H2WO4 and Na2WO4.2H2O. For the synthesis of fibers by electrospinning the reagents used were: glacial acetic acid, titanium propoxide, 10% polyvinylpyrrolidone, tungstic acid and sodium tungstate dihydrate. The obtained fibers were heat treated between 650 °C and 800 °C, with a 1 hour threshold and a heating rate of 1.4 °C/min. To obtain the films by spin-coater were prepared solutions containing: 0.25 g of treated fibers between 650 ºC and 800 ºC, anhydrous ethanol, acetylacetone, Triton X-100 and polyvinylbutyral. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission (TEM), thermogravimetric (TGA) and thermo-differential analysis (DTA), diffuse reflectance spectroscopy (ERD), profilometry, Brunnauer Emmet and Teller (BET) theory, 125 ml degradation assays of a 20 ppm solution of methyl orange dye and colorimetry through the system CIELa*b*. The best results were obtained with TiO2/Na2WO4.2H2O samples. These samples were more efficient in the methyl orange dye mineralization, since 3 of the 4 synthesized samples degraded approximately 100% of the dye and simultaneously expressed the highest values of reflectance, possibly due to the existence of a synchronization between the chemical and physical characteristics of these oxides and the formation of point defects (vacancies) that occupy atomic network positions.
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Nitrogen Doped Titanium Dioxide in the Photocatalytic Degradation of Methylene BlueUpadhyaya, Ashraya 01 May 2018 (has links)
Titanium dioxide(TiO2) is a stable, effective and well-known photocatalyst for degradation of pollutants. However, its practical applications are limited due to the need for energy higher than 3.2 eV, or a wavelength lower than 390 nm (high frequency waves, ultraviolet and above) hindering its ability to effectively work in the visible light region (about 400 nm to 700 nm). Nitrogen-doped TiO2 (N-TiO2) has garnered some attention as a photocatalyst as it appears to work even in the visible light region. This could allow the utilization of a larger part of the solar spectrum. This thesis presents the results of photocatalytic degradation of methylene blue (MB) carried out under simulated visible light by using TiO2 and N-TiO2(doped in the lab) to evaluate and compare their efficiencies under similar conditions.
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Decomposition of Acetone by Nano-sized Photocatalysts Coated on Activated Carbon Cellulose-paper FilterPeng, Yi-wei 27 August 2008 (has links)
This study combined photocatalytic technology with activated carbon cellulose-paper filter (ACCF) adsorption to decompose gaseous pollutants. Gaseous pollutants were initially adsorbed by activated carbon and could be further decomposed by photocatalytic technology.
This study selected acetone (CH3COCH3) as gaseous pollutants. Two market available photocatalysts (photocatalysts¢¹and¢º) were coated on ACCF by impregnation to decompose acetone in a batch photocatlytic reactor. Operating parameters investigated in this study included initial acetone concentration (4.1~10.2 £gM), reaction temperature (40~70¢J), and water vapor (0~20 %). The incident UV light of 365 nm was irradiated by a 20-watt low-pressure mercury lamp placing above the batch photocatalytic reactor. The ACCF coated with TiO2 was placed at the center of the photocatalytic reactor. Acetone was injected into the reactor by a gasket syringe to conduct the photocatalytic tests. Reactants and products were analyzed quantitatively by a gas chromatography with an electron capture detector (GC/DCD) and a flame ionization detector followed by a methaneizer (GC/FID-Methaneizer). Finally, a Langmiur-Hinshewood (L-H) kinetic model was proposed to describe the rate of photocatalytic reaction.
Results obtained from the photocatalytic tests indicated that photocatalyst¢º was better than photocatalyst¢¹ for the decomposition of acetone. Experimental results indicated that the size range of self-produced TiO2 photocatalyst by sol-gel was 20~70 nm. The end products were mainly CO and CO2, which resulted in the mineralization ratio up to 98%. Results obtained from the operating parameter tests revealed that the increase of initial acetone concentration enhanced the amount of acetone adsorbed on ACCF, which however did not increase the reaction rate of acetone. Although the increase of reaction temperature could reduce the amount of acetone adsorbed on ACCF, the decomposition rate of acetone could be promoted, so as the yield rate and mineralization ratio of products (CO and CO2). The increase of water vapor could slightly decrease the amount of acetone adsorbed on ACCF. The competitive adsorption phenomenon between acetone and water molecules on active sites could decelerate the decomposion of acetone. Moreover, the ACCF would not be saturated since the adsorbed acetone could be further decomposed quickly by the photocatalysts, which made the TiO2/ACCF more effective on removing acetone and lasted longer than the conventional ACCF.
Finally, a modified bimolecular Langmuir-Hinshelwood kinetic model was developed to investigate the influences of initial acetone concentration reaction, temperature, and relative humidity on the promotion and inhibition for the photocatalytic oxidation of acetone. The modified L-H kinetic model could successfully simulate the photocatalytic reaction rate of acetone. Thus, the reaction rate of acetone over TiO2/ACCF could be described by the modified L-H kinetic model.
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