Dissertations / Theses on the topic 'Photocatalysis Self-Cleaning'

This thesis focuses on the application of nanocrystalline transition metal oxide TiO2, WO3 and NiO thin films in new “green” building technologies. Specifically, their physicochemical properties in photocatalytic, self-cleaning and gas sensing applications are studied. There is an intimate connection between comfort issues, health, with connections to energy efficiency, leading to a need for intelligent building materials and green architecture. The importance of good indoor environment is augmented by the fact that modern man in developed countries spends some 90 % of his time inside buildings and vehicles. Poor air quality may lead to discomfort of the person inhabiting a building and in ultimately cause adverse health effects. Thin films of nanocrystalline TiO2 were prepared using reactive DC magnetron sputtering. Crystalline mesoporous films of WO3 and NiO were prepared using advanced gas deposition technique (AGD). The crystal structure, morphology, optical and chemical properties of the films were characterized by using grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM), UV/Vis spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. The photocatalytic properties and adsorption of both organic and inorganic molecules on pure and functionalized films were probed by in situ Fourier transform infrared spectroscopy (FTIR). The gas sensing properties of sensors based on TiO2, WO3 and NiO were investigated by conductivity measurements and noise spectroscopy. It was found for the first time that NiO based thin film sensors can be used to detect H2S and NO2 at low temperatures – down to room temperature. Hybrid WO3 sensors functionalized with multiwalled carbon nanotubes (MWCNTs) were used to detect NO2, CO and NH3 gases. These hybrid gas sensors show improved recovery properties compared to unmodified WO3 sensors. TiO2 based gas sensors were able to detect low concentrations of H2S by noise spectroscopy provided that the sensors were irradiated by UV light. Furthermore we show that sulphur is photo-fixated in crystalline TiO2 films upon simultaneous SO2 gas exposure and UV irradiation. Studies of the kinetics and identity of the photo-fixated sulphur complexes show that these are formed by photo-induced reactions between oxygen and SO2 at oxygen surface vacancy sites in TiO2. The sulphur modified TiO2 films show interesting self-cleaning properties compared to the pure films.
Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 739

Semiconductor metal oxides can be induced by light with proper wavelength resulting in oxidation and reduction reactions for the transformation of water and oxygen molecules into active radicals. With this method, it is possible to obtain self-cleaning surfaces and products having antimicrobial properties. The aim of this study is to develop semiconductor metal oxide thin films for multifunctional glass products and the characterization of photocatalytic self cleaning and antimicrobial properties. As semiconductor metal oxides
titanium dioxide (TiO2), tin oxide (SnO2) and their binary mixtures (TiO2-SnO2) are selected because of their abundancy, non toxic properties, stability and the ability of absorbing light close to visible range. Also the effect of metal dopants such as praseodymium (Pr), palladium (Pd), silver (Ag) and iron (Fe) was examined with these metal oxides. The colloidal solutions were synthesized by using sol-gel method in order to apply the developed method to industrial usage as applying on large surfaces. The glass substrates were coated with the colloidal solutions by dip coating and the dried samples were calcined under air flow. The best calcination condition for pure TiO2 coated thin film was determined as 400oC for 45 minutes. Surface characterization studies were performed by using UV-Visible Spectrophotometer for band gap measurement, CAM for contact angle measurement, SEM for surface morphology and tophology. The methylene blue adsorption tests were carried out and the effective surface area of the samples were predicted by the Langmuir adsorption isotherm of samples. The photocatalytic activities of the coated thin films were measured with the degradation of organic materials as red wine and methylene blue, and with the antimicrobial activity tests as counting the number of viable E.coli cells. 61.2% deactivation of methylene blue stain was achieved over SnO2 coated thin films while this was 22.1% over TiO2 coated thin films after irradiation for 180 minutes. The superior photocatalytic activity was observed with TiO2 samples doped with Pd and Ag ions. The TiO2-SnO2 coated samples performed limited photocatalytic activity which is less than the activity of SnO2 coated samples which was confirmed with surface area measurements as SnO2 coated samples had higher surface area (9.81 cm2/cm2) than TiO2-SnO2 coated samples. Surface area increased with increasing the amount of SnO2 and it was in the following order: SnO2 >
80% SnO2 + 20% TiO2 >
50% SnO2 + 50%TiO2 >
35% SnO2 + 65%TiO2 >
20% SnO2 + 80% TiO2 >
TiO2.

Poor indoor air quality is a source of adverse health effects. TiO2 coatings deposited on well-illuminated surfaces, such as window panes, can be used to fully mineralize indoor air pollutants by photocatalysis. In such applications it is important to ensure stable photocatalytic activity for a wide range of operating conditions, such as relative humidity and temperature, and to avoid deactivation of the catalyst. In this thesis photocatalytic removal of the indoor-pollutant acetaldehyde (CH3CHO) on nanostructured TiO2 films is investigated, and in particular it is proposed how such films can be modified and operated for maximum performance. Catalyst deactivation can be reduced by purposefully changing the surface acidity of TiO2 by covalently attaching SO4 to the surface. Moreover, the overall photocatalytic activity on anatase TiO2 films can be improved by increasing the fraction of exposed reactive {001} surfaces, which otherwise are dominated by {101} surfaces. In the first part of the thesis mode-resolved in-situ FTIR is used to elucidate the reaction kinetics of CH3CHO adsorption and photo-oxidation on the TiO2 and SO4 – modified TiO2 surfaces. Surface concentrations of main products and corresponding reaction rates were determined. Formate is the major reaction product, whose further oxidation limits the complete oxidation to gaseous species, and is responsible for photocatalyst deactivation by site inhibition. The oxidation reaction is characterized by two reaction pathways, which are associated with two types of surface reaction sites. On the sulfate modified TiO2 catalyst fewer intermediates are accumulated, and this catalyst resists deactivation much better than pure TiO2. A hitherto unknown intermediate – surface-bound acetaldehyde dimer with an adsorption band at 1643 cm−1 was discovered, using interplay between FTIR spectroscopy and DFT calculations. The second part of the thesis treats the effect of increasing the relative abundance of exposed {001} facets on the photocatalytic activity of anatase TiO2 films prepared by DC magnetron sputtering. A positive effect was observed both for liquid-phase photo-oxidation of methylene blue, and for gas-phase photocatalytic removal of CH3CHO. In both cases it was found that the exposed {001} surfaces were an order of magnitude more reactive, compared to the {101} ones. Furthermore, it was found that the reactive films were more resilient towards deactivation, and exhibited almost unchanged activity under varying reaction conditions. Finally, a synergetic effect of SO4 – modification and high fraction of exposed {001} surfaces was found, yielding photocatalysts with sustained high activity. The results presented here for facet controlled and chemically modified TiO2 films are of interest for applications in the built environment for indoor air purification and as self-cleaning surfaces.
GRINDOOR

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.

A transformative advance in the field of sensor technology has been the development of smart sensor systems. One major implication of smart sensor systems is the use of robust and reliable sensing devices. lt could appear to be trivial, but even the most intelligent system is completely useless if its sensing core does not work properly. For this reason, it is of paramount importance to develop highly efficient sensing platforms with self-calibrating, self-healing, self-compensating and selfcleaning properties. This is one of the most challenging and actual field of research, which benefited much from the "nanotechnology revolution", generating high promises especially for the development of miniaturized devices. This broad field crosses many different disciplines ranging from chemistry to physics to materials science, with a major role played by surface science. The scope of this Thesis is to explore three different, although converging, approaches to develop such kind of sensing platforms. The enabling roles of photocatalysis, polymer brushes and of exotic characterization techniques (such as positron annihilation spectroscopy) to reach this goal are discussed. Theoretical as well as highly applicative results are described, as products of a genuine curiosity-driven approach.

Ao longo do tempo, os revestimentos de fachada permanecem expostos a diversos agentes de degradação, sejam eles associados aos próprios materiais empregados ou a fatores externos. Tal exposição implica em manchas formadas a partir da deposição de partículas poluentes na superfície dos revestimentos, elevando seus custos para limpeza e manutenção. Uma vez que permanecem expostas à radiação solar, as fachadas se mostram atraentes ao uso de materiais fotocatalíticos, os quais catalizam a mineralização de agentes poluentes, transformando-os em produtos inócuos. A adição de dióxido de titânio (TiO2) a argamassas e concretos de cimento branco desenvolve superfícies autolimpantes, reduzindo a formação de manchas e mantendo sua coloração original ao longo do tempo. No entanto, a eficiência e a economia no uso de materiais fotocatalíticos em aplicações reais é fortemente afetada pela disponibilidade da radiação ultravioleta adequada para ativá-los. Portanto, o presente trabalho busca avaliar a capacidade autolimpante de argamassas e coberturas fotocatalíticas de TiO2 expostas a diferentes configurações de posicionamento no microclima urbano da cidade de Porto Alegre. Para isto, foram confeccionadas amostras de argamassa e coberturas de pasta ou argamassa contendo diferentes teores de TiO2, as quais foram manchadas com Rodamina B e lodo de cinzas da queima de eucalipto e, a seguir, expostas sob diferentes condições de posicionamento, voltadas para as orientações norte, sul, leste e oeste, à 0º, 45º e 90º. Ao longo do período de exposição, foram realizadas leituras cromáticas (sistema CIELab) na superfície das amostras, tendo em vista a descoloração dos manchamentos aplicados. Para aquelas manchadas com Rodamina B, a degradação do corante se mostrou mais eficiente nas argamassas com maiores teores de TiO2 e nas configurações de posicionamento que recebem maior incidência de radiação solar. As coberturas de pasta apresentaram valores mais elevados de variação de cor (ΔE) e refletância (L*), na comparação à aplicação do TiO2 como cobertura de argamassa ou incorporado à mistura − métodos os quais se mostraram resultados equivalentes.
Building façades are commonly exposed to polluting agents generated by vehicles and industries exhausts, which cause stains on their surfaces and increase efforts and costs both for cleaning and maintenance. Facades are attractive to photocatalytic materials usage, which transform pollutants to innocuous products. The addition of titanium dioxide (TiO2) to white cement mortars and concretes develops self-cleaning surfaces which are capable to reduce stains and maintain their original color along the time. However, efficiency and economy in the use of photocatalytic materials in real applications are strongly affected by the availability of suitable ultraviolet radiation to activate them. This thesis aims to evaluate the self-cleaning ability of TiO2-containing mortars and coatings (paste or mortar) exposed to controlled positioning settings in the urban environment of Porto Alegre, Brazil. Mortars and coatings were prepared containing different additions of TiO2 and then were soiled by Rhodamine B (RhB) or burning ashes of eucalyptus sludge. Samples were exposed under outdoor conditions facing north, south, east and west orientations, 0º, 45º or 90º slopes. During the exposure test, discoloration effect on samples' surface was monitored by colorimetric measurements (CIELab color space) using a portable spectrophotometer. A final analysis was performed at the end of the measurements, including statistical tests. Self-cleaning ability was better seen both for higher additions of TiO2 and settings which receive higher intensities of solar radiation. Cement paste coatings showed higher values both of color change and reflectance when compared to mortar coatings or TiO2 added to the mixture − which performed equivalent results.

This thesis is focused on gathering all available information on the application forms of photocatalytic TiO2 in concretes, especially in the surface layers of precast and monolithic structures. The paper describes in detail the properties of titanium dioxide alone, his special abilities, leading to a substantial improvement of the environment, through photocatalysis. Further verification methods are described photocatalytic activity of titanium dioxide and titanium dioxide application in real projects. The practical part is tested recipes of secondary coatings from the production of company Precheza a.s. Přerov.

Actuellement, le marché du bâtiment est demandeur de nouveaux matériaux, et notamment de vitrages, exigeant peu d'entretien. Pour cela les surfaces photoréactives à base de dioxyde de titane sont très bien adaptées ; soumises à un rayonnement ultraviolet, elles peuvent dégrader photocatalytiquement un grand nombre de salissures organiques et l'utilisation de nanoparticules permet d'obtenir un verre optiquement neutre. Le travail présenté porte sur la caractérisation photoélectrochimique de ces surfaces photoréactives constituées de TiO2 sous forme nanoparticulaire entouré d'un liant nécessaire à la tenue mécanique des nanoparticules. Les mesures photoélectrochimiques ont permis de caractériser les propriétés semi-conductrices de ces nanoparticules et d'observer certains comportements inhabituels. De plus, l'analyse combinée des données de photoélectrochimie et de photocatalyse a permis d'élucider le fonctionnement de cet assemblage nanoparticules-liant. Il apparaît que la paire électron-trou se crée dans la nanoparticule semi-conductrice, que le liant permet l'évacuation de l'électron par un positionnement de ses bandes d'énergie adéquat et que l'ensemble peut être contrôler pour produire les vitrages auto-nettoyants à base de nanoparticules de TiO2 les plus performants
Nowaday, the building market is looking for new materials, especially glasses with self-cleaning properties which do not need much maintenance. Photoreactive surfaces containing titaniµm dioxide nanoparticles seem to be very well suited to this application. In fact, under an UV radiation, these surfaces are able to degrade, by mean of a photocatalytic process, a wide range of organic residues. This work consists in the photoelectrochemical characterisation of thoses photoreactive surfaces made with TiO2 nanoparticles and a binder. By photoelectrochemistry, it was possible to characterized the semi-conductìng properties of thoses nanoparticles and to observe an unusual behavior. The analysis of all the datas issues of photoelectrochemícal and photocatalytical experiments allowed to elucidate a mechanism involving a co-operation between the nanoparticles and the binder. The electron-hole pair is created in the nanoparticle and the binder supports the evacuation of the electron by an adequate band energy level. Acting on the nanoparticles-binder system, it could be possible to obtain the best performing self-cleaning glasses

Pollution in water and atmosphere is a growing concern in the current society and demands short-term solutions. Conventional purification techniques like biological treatment, direct oxidation, etc. cannot eliminate low concentrations or some of the so-called emerging pollutants (hormones, detergents, pharmaceuticals, etc.) thus calling for the use of advanced oxidation processes (AOP), namely, techniques in which highly oxidising agents (mostly OH radicals) are produced to degrade organics compound, bacteria and viruses, reaching the complete mineralization or, at least, producing nontoxic by-products. One of these techniques is heterogeneous photocatalysis: redox reactions are developed on the surface of a solid catalyst that is activated by light. Nowadays the more employed and studied photocatalyst is titanium dioxide (TiO2). Its commercial applications are very diverse, including self-cleaning materials (cements, paints), antifogging materials (mirrors, glasses) and water and air purification devices. The operating limits of this effective photocatalyst are in the fact that it needs UV radiation to be activated, due to its relatively wide band gap (3.2 eV). This is a significant problem in economic terms, for high energy costs, in healthy terms, since UV radiation is dangerous for sight and skin, and it is a limit to the use of sunlight, as only 4 % of the solar spectrum that reaches the Earth surface is in the UV range. To overcome this problem, investigations are focused on TiO2 modifications to render it active with visible light (doping with metal and non-metal ions, coupling with other semiconductors, etc) as well as on the use of other semiconductors with narrower band gap. A ceramic material, lanthanum orthoferrite (LaFeO3), with ionic and electronic semiconductor properties, is synthesized in our laboratory since 2008 and it is studied for its application in the combustion cells. Knowing that it also works as photoconductor under visible light [3], it can be considered a good candidate to be used as visible light photocatalyst. Its effectiveness in the degradation of organic dyes and other molecules has been reported. After the successful degradation of organic compounds in the slurry tests carried up with the LaFeO3 powders, our group started to develop deposition systems in order to avoid filtration problems, such as loss of catalyst and costs, thus rendering the reuse of the photocatalyst easier to achieve a practical applicability. In the present thesis two deposition methods were studied: the preparation of a photocatalytic paint and the deposition of the catalyst over a ceramic foam by dip-coating process. In the first part of the work, LaFeO3 was added to a commercial water based paint. This innovative photocatalytic paint has been tested to prove two aspects: • Its self-cleaning performances, following the degradation of an azo dye under visible light irradiation. • The paint durability, executing accelerated ageing tests in a climatic chamber, and subsequently verifying visible alterations and possible diminution of its self-cleaning performances. In the second part, the objective was the application of the material for the wastewater treatment. In collaboration with the Universidad de Las Palmas de Gran Canaria a handy and resistant photocatalytic foam was developed, to avoid the vigorous continuous stirring required to keep powder in slurry and the necessary filtration after the reactions to reuse the photocatalyst. The support chosen was a commercial ceramic inert porous material (foam) and the deposition method was the dip-coating technique. To apply this coating technique high quantities of catalyst had to be used because it required the preparation of a very concentrate solution. For this reason and for a possible scaling up, the production rate of the photocatalyst in our laboratory had to be increased. The quality of the catalyst had been largely tested for low production rates. Theoretically the results of the synthesis must be the same; however, a complete characterization and determination of photocatalytic performances were carried out on three batches of catalyst prepared on a large scale. The photocatalytic foam and the different batches in slurry were tested in the degradation of 4-Nitrophenol. A comparison between the slurry test and the fixed bed test is presented.

Tenké vrstvy oxidu titaničitého byly imobilizovány na sodnovápenatá skla a skelný uhlík použitím jak techniky materiálového tisku tak metodou chemického napařování. Pro přípravu titaničitých solů byly použity metody sol-gelu a nebo hydrotermální syntézy. Struktura připravených vrstev byla zkoumána rastrovací elektronovou mikroskopií a mikroskopií atomárních sil. Krystalická struktura připravených TiO2 byla analyzovány pomocí XRD metody. Fotoindukováná superhidrofility pripravených vzorků byla charakterizována měřením kontaktních úhlů. Fotokatalytická aktivity připravených vzorků byla testována na fotokatalytické oxidaci 2,6-dichlorindofenolu a kyseliny mravenčí. V případě sol-gel vrstev byl zkoumán vliv množství naneseného TiO2 a množství PEG, který byl do solu přidán jako praskliny potlačující činidlo. V případě hydrotermálních vrstev byl zkoumán vliv času a teploty syntézy a množství vrstev na výslednou účinnost vzorku. U chemicky napařených vzorků byl zjišťován vliv intenzity záření. Byla porovnána fotokatalitická aktivita vrstev připravených materiálovým tiskem a chemickým napařováním a byl vyhodnocen nejaktivnější vzorek.

In this study photocatalytic antibacterial and self-cleaning activities of TiO2-SiO2 thin films as a function of TiO2/SiO2 ratios were investigated. TiO2-SiO2 mixed oxides were synthesized by sol-gel method and coated over soda-lime glass plates by dip coating technique. Escherichia coli was used as a model microorganism for the photocatalytic antibacterial tests. Degradation rate of methylene blue (MB) molecules was used to characterize photocatalytic self-cleaning activities of thin film surfaces. The maximum antibacterial activity was achieved over 92 wt% SiO2 containing thin films. However, when the SiO2 content exceeds 92 wt%, photocatalytic antibacterial activity decreased considerably, which was explained by the dilution of TiO2 phase and inaccessibility of TiO2. Increase in photocatalytic antibacterial activity was attributed to increases in the relative surface area, roughness, hydroxyl (OH-) groups and bacterial adhesion. The favored bacterial adhesion enhanced direct contact of bacteria with TiO2 particles and surface reactive oxygen species. The highest initial decomposition rate of MB was obtained for 60 wt% SiO2 and the activity decreases as SiO2 concentration increases. The increase in photocatalytic activity by the SiO2 addition can be explained by the increase of the amount of MB per unit area of TiO2-SiO2 thin films. Different adsorption capability of thin films against MB molecule and E. coli cell was explained as the first reason why the antibacterial and self-cleaning activities reached their maximum values at different SiO2 ratios. The second reason could be related with the different control mechanisms of self-cleaning and antibacterial activities by different textural and surface properties.

Avec une industrialisation mondiale en croissance continue atteignant 6,1% en 2021 et un fardeau démographique de 8 milliards de personnes, le monde d'aujourd'hui est confronté aux pénuries d'énergie les plus importantes et à la pollution environnementale la plus étendue de son histoire. Particulièrement, les effluents chargés de molécules toxiques organiques récalcitrantes provenant des raffineries, de l'industrie pétrochimique, pharmaceutique, des plastifiants et de nombreuses autres industries mettent en danger la durabilité des eaux de surface et des eaux souterraines. Avec l'inefficacité des techniques de traitement conventionnelles pour résoudre ce problème, les processus d'oxydation avancée (AOP) sont apparus comme une technologie efficace, prometteuse et peu coûteuse, capable de s'attaquer à différents types de molécules organiques dans les milieux aquatiques. Parmi ces techniques, la photocatalyse hétérogène est apparue comme l'une des méthodes les plus efficaces et économiques en raison de la réutilisabilité du photocatalyseur et de l'absence de besoins en matière d'élimination secondaire. La technique est basée sur la génération d'espèces d'oxygène hautement réactives (ROS) lors de l'exposition d'un matériau photocatalytique à la lumière, conduisant à une technologie verte et durable. Ces ROS sont bien connus pour leur forte capacité d'oxydation de la matière organique, conduisant à leur minéralisation en molécules d’eau et dioxyde de carbone. Pour cette raison, le développement d'un photocatalyseur efficace et respectueux de l'environnement est important. Dans ce contexte, l'oxyde de zinc (ZnO) a attiré une grande attention à cause son efficacité élevée de conversion de l'énergie photonique, de son faible coût de production, de son faible degré de toxicité pour la vie marine/humaine et de sa longue durée de vie. Cependant, l'un des principaux défis auxquels ce matériau est confronté est l'efficacité photocatalytique limitée en raison de la recombinaison des paires électron-trou. Par conséquent, de nouvelles stratégies ont été développées pour améliorer son activité photocatalytique, telles que la conception de nouvelles micro/nanostructures de ZnO ou le couplage des photocatalyseurs avec d'autres techniques de traitement pour produire des effets synergiques. L'objectif de cette thèse est de concevoir de nouveaux types de nanostructures de ZnO pour dégrader efficacement les contaminants toxiques en phase liquide ou gazeuse. Pour cette raison, l'impact de la structure chimique des polluants sur la cinétique de dégradation a d'abord été étudié sur diverses molécules organiques toxiques. Ensuite, le système photocatalytique a été adapté pour la photodégradation de particules de microplastiques d'une taille de 300 μm. Les effets de la morphologie et de la microstructure sur l'activité photocatalytique du ZnO ont été étudiés afin d'améliorer l'efficacité du système photocatalytique. Pour y parvenir, des nanobâtonnets, des couches minces poreuses et plissées ont été synthétisés en optimisant les techniques de sol-gel et de croissance hydrothermale en milieu liquide. Bien que les nouveaux matériaux aient montré une cinétique de dégradation améliorée, le taux de recombinaison rapide des paires electron-trou continuait néanmoins de freiner son activité photocatalytique. Pour surmonter cette limitation, une oxydation photo-Fenton-like a été couplée au photocatalyseur ZnO. Quand les deux processus fonctionnant simultanément, un effet synergique a été obtenu grâce à la diminution de la recombinaison électron-trou d'un côté, et la régénération du réactif Fenton de l'autre côté. De plus, une nouvelle matrice de ZnO macroporeuses a été conçue en couplant la chimie sol-gel avec l'auto-assemblage de copolymères en bloc. Le nouveau matériau a présenté des propriétés d'auto-nettoyage remarquables lorsqu'il a été appliqué sur des surfaces revêtues
With a continuously growing global industrialization reaching 6.1% in 2021 and a demographic burden of 8 billion people, today’s world is facing the most extensive energy shortages and environmental pollution in its history. Particularly, loaded effluents with recalcitrant organic toxic molecules from refineries, petrochemicals, pharmaceuticals, plasticizers, and many other industries, are continuously endangering surface and groundwater water sustainability. With the low efficiency of conventional treatment techniques in addressing this issue, advanced oxidation processes have emerged as an efficient, promising, and inexpensive technology, capable of tackling different types of organic molecules in aquatic mediums. Amongst these techniques, heterogeneous photocatalysis has emerged as one of the most efficient and economical methods due to the photocatalyst reusability and lack of secondary disposal requirements. The technique is based on the generating of highly reactive oxygen species (ROS) such as hydroxyl radical and superoxide radical upon the exposure of a photocatalyst material to light, making it a green and sustainable technology. These ROS are well-known for their strong oxidation capacity toward organic matter, leading to their mineralization into harmless molecules such as water and carbon dioxide. For that reason, developing an efficient and eco-friendly photocatalyst is of great importance. In this scope, Zinc oxide (ZnO) has been attracting high attention due to its high conversion efficiency of photonic energy, low production price, low degree of toxicity to marine/human life, and long life span. Nonetheless, one of the main challenges facing this material is the limited photocatalytic efficiency due to the recombination of electron-hole pairs. Therefore, new strategies have been developed to enhance its photocatalytic activity such as designing new micro/nanostructures of ZnO or coupling the photocatalysts with other treatment techniques to produce synergic effects

Nous avons étudié la croissance, sur des tissus en polyester, de nano-colonnes de ZnO par méthode hydrothermale. Un prétraitement par plasma a permis de générer des groupements polaires à la surface des fibres. Ces groupements permettent d’accrocher des nano-germes de ZnO à partir desquels d’effectue la croissance des cristaux de ZnO. La nature de la composition chimique de surface à chaque étape du traitement a été suivie par XPS. La morphologie et la structure des cristaux formés a été caractérisée par MEB, XRD et MET. La quantité totale de ZnO déposée sur le tissu a été déterminée par spectroscopie d’absorption atomique. La croissance de ces nano-colonnes de ZnO sur les microfibres de PET génère une structure rugueuse hiérarchique. Les tissus obtenus sont superhydrophiles : le mouillage et la capillarité de l’eau deviennent très importants et augmentent avec la concentration en germes. Après hydrophobisation avec l’ octadecyltrimethoxysilane (ODS), le tissu fonctionnalisé présente un effet lotus autonettoyant avec des angles de contact et de glissement de l’eau caractéristiques. L’effet chimique autonettoyant a été aussi mis en évidence avec la décoloration de solutions et de taches sous rayonnement UV. La cinétique de ces 2 effets photocalytiques a été étudiée avec différents colorants. Ce tissu présente un caractére antibactérien, il est donc aussi autonettoyant vis-à-vis des espèces biologiques Escherichia coli, Pseudomonas aeruginosa et Staphyloccocus aureus. Cette étude met en évidence les relations entre les procédés de nanostructuration de la surface des fibres dans les tissus et leurs propriétés autonettoyantes selon les 3 mécanismes proposés
ZnO nanorods were grown on polyester fabric by hydrothermal method. The plasma treatment was carried out to generate the polar groups. These groups attached the ZnO seeds which provided the site for the growth of nanorods. XPS analysis was carried out to study the chemical composition of surface at each stage of growth. The morphology and crystal structure was characterized by SEM, XRD and TEM. The atomic absorption spectroscopy was carried out to determine the amount of Zn present on fabric in the form of nanorods. The growth of nanorods on microfibers of PET generated hierarchical roughness structure. The functionalized fabric showed superhydrophilicity: very high wettability and capillarity which increased with the increase in seed concentration. On modification with hydrophobic chemical (octadecyltrimethoxysilane ODS), the functionalized fabric showed physical self-cleaning (lotus effect) which was characterized by measuring water contact angle and water roll off angle. The chemical self-cleaning was studied by solution discoloration and stain degradation under the effect of UV light. It was found that solution discoloration followed first order kinetics whereas; stains were degraded by second order kinetics. The biological self-cleaning (antibacterial activity) was also observed on Escherichia coli, Pseudomonas aeruginosa and Staphyloccocus aureus. This study highlights the relationship between nanostructuring process of the fibers and self-cleaning properties according to the three proposed mechanisms

There are a number of “smart” coatings that can be applied to glass. These include self-cleaning coatings based on titanium dioxide, and low-E coatings based on fluorine-doped tin oxide. Products are often more desirable with colour options such as Pilkington Activ BlueTM. There are currently no alternatives to body tinting glass to achieve colour, which is a time-consuming and expensive procedure. The work in this project details a number of coloured coatings via the AACVD or combustion processing of metal nitrate/urea precursors.

During this project, photocatalytic material, nano sized titanium dioxide, was introduced into poly (lactic acid) to produce functional surface capable of self-cleaning property. Samples containing 0%, 5%, 10%, 15% and 20% titanium dioxide were prepared and etched with proteinase K to expose the nano particles on the surface. It was shown that the nano titanium dioxide could dispersed in the polymer matrix pretty well, it was also found that the nano particles affected the thermal and mechanical properties of the polymer matrix differently , due to difference in concentrations of nano filler. The self-cleaning property was evaluated by decolouration of stains caused by coffee and red wine, also by detecting degradation of methylene blue via a UV-vis spectrophotometer. By measuring changes in absorbance of light at 664nm wavelength after a maximum of 24h UV irradiation, it was possible to measure the degradation property of the samples.
Program: Masterutbildning i textilteknik

Most of the topics dealt with in this thesis belong to surface science. The starting point was the fundamental understanding of phenomena at the oxide-gas interface and the effect of its modification. Such knowhow was then used to solve (or, at least, to attempt to solve) issues of critical impact in everyday life: the increasing lifetime of building materials employed in low-impact smart houses; the fouling prevention in electroanalytical sensors for neurotransmitter detection; the unspecialized laboratories accessibility to microlithography, critical to device miniaturization. These challenges might seem not related, but they actually share deep scientific and technological foundations. The physicochemical modification of oxide surfaces, the creation of organic/inorganic hybrids and the exploiting / the enhancing of semiconductor peculiar properties allowed us, starting from the foundation, the realization of proof-of-concept protocols and devices, ready for the pre-commercial development. The Leitmotif of my research was the synthesis and the modification of titanium dioxide surfaces. TiO2 has been the main character in physico, physicochemical and material science researches of the last 50 years. Biocompatibility and low cost make it engaging for many applications. Its (near-UV active) semiconductor features, well known and abundantly investigated by the scientific community, are acquiring central interest also in many markets with the development of self cleaning coatings, windows and asphalts, anti-fogging mirrors and self-sterilizing surgery rooms and instrumentations. New generation batteries and solar cells are going to be developed as commercial prototypes. One of the biggest challenges in the titania fundamental research is the enhancement of activity in the solar spectrum. First, the most recent aspects in titania doping and promotion were touched. While, in the last twenty years, great effort has been made in the mono-atomic doping of titania and in the understanding of the influence of the dopant position in the titania lattice and its electronic behavior, the most recent literature describes the co-promotion of the material by two (or more) atoms doping. The metal/non-metal codoping seems especially promising; the synergetic effect of the two atoms in the TiO2 lattice was both theoretically and experimentally proved. In this contest, the N/Nb codoping was analyzed, investigating the effect of the atoms in the lattice from morphological (surface area, porosity and crystallographic structure) and electronic point of view (EXAFS, UV-Vis absorption and EPR analyses). N/Nb codoping was compared with N/Ta co-doped samples, synthesized by two different procedures. The photoactivity of the two sample families was tested by a model reaction (the degradation of ethanol, throughout acetaldehyde intermediate) both under UV and solar simulated irradiation. Then, a different approach in the modification of surfaces was tested. The assembly of organic/inorganic hybrids was tested; thanks to the formation of organic mono- or multi-layers at the surface,they can tune the chemistry, the polarity and the adhesion properties of the interface. Siloxanes were used as active agents, thanks to their compatibility with oxide materials and, especially, for the ability to self-assemble at the surface to form a monolayer. Siloxanes are able to react with the -OH groups at the surface, chemisorbing and polymerizing at the interface in such a way to form a monolayer with tunable functionalities. Many different silanes were tested and their dipole momenta were related to their wettability properties. Such siloxanes chemisorb strongly both from the gas phase and the liquid phase. Their reactivity, both on smooth and rough surfaces, was tested vs the temperature of functionalization in gas phase. Many characterization techniques were adopted to understand the behavior of such molecules from a molecular point of view: magnetic (solid state NMR), microscopic (SEM, TEM, AFM), optical and electrochemical (CV and EIS). The science of adhesion and wettability was also adopted for the development of superhydrophobic coatings. Titanium dioxide particles with engineered morphology were used as the best candidate to create superhydrophobic/superhydrophilic patch-wise surfaces, exploiting their photoactivity (photolithograpy). The core of the thesis was the synthesis, modification and application of transparent photoactive thin films. A procedure for the synthesis of smooth, transparent and photoactive TiO2 thin layers was developed, and used to produce highly applicative devices and protocols. Such synthetic strategy is highly tunable and reproducible; the obtained films are robust and active and, most of all, require simple instrumentation (sol-gel procedure), which is highly appealing for the market. The films were properly characterized both form the morphological/mechanical and photochemical point of view. Apart their transparency and their thickness, the films were highly crystalline (pure anatase phase). Such procedure was firstly designed as a proof-of-concept for self-cleaning windows, but, thanks to its versatility and the high activity of the films, it leads the path towards highly applicative procedures and devices. The smoothness and the photoactivity brought me to the field of photolithograpy, especially in the direction of microlithography. The high activity of the titania allowed the use of safe and low-energetic lamps. No collimation was required to obtain a resolution lower than 5 µm. First of all, I tested the lithography on siloxane monolayer films, as a proof-of-concept of resolution and efficiency. But siloxanes, as many other self-assembled monolayer molecules, can be the pillars for 3D fabrication. Such monolayers were used as polymerization initiators for polymer brushes. If the initiators of polymerization are patterned, patterned polymer brushes will be obtained. That was the first report of polymer-brushes lithography exploiting the photoactivity of TiO2. Remote photocatalytic lithography makes this procedure extremely versatile. Exploiting the remote photocatalysis, in principle, any material can be used as a support for patterned polymer brushes growth (provided that the initiator are able to graft the surface). The developed protocol for the synthesis of TiO2 thin films was also used to design and engineer complex electrodes for cyclovoltammetric analyses of biological samples. Electrochemistry seems to be the best candidate for the development of an analytical option with sensitivity comparable with present analytical procedures but reduced time-per-analysis and cost. Unfortunately, catecholamines chemisorb and polymerize on metal and oxide electrodes quickly, making the device useless. Covering the electrode by a homogeneous, nano-porous thin layer of titania makes the surface photoactive. That is the first example in literature of self-cleaning nano-engineered electrodes for cyclic voltammetry. After the detection, also in simulated human serum and liquor, a fast and simple irradiation of the device, under non-hazardous UV-A lamp, degrades all the fouling on the surface without altering its features. The sensor, after each UV treatment, recovers its pristine performances, with full recovery in terms of selectivity and sensitivity. Irradiation trials were also performed directly in the analytical mixture, as a proof of concept for on-site application. Modern era requires flexible and light materials for the building industry. Polymers are acquiring more and more interest thanks to their increasing performances and their smart properties. The drawbacks of such materials are connected to the low resistance to the UV light, the softness and the difficulties in cleaning procedure. The use of organic/inorganic hybrid, or better the coverage of plastic materials with an oxidic thin layer, can solve many of these problems, lengthening the lifetime of such materials. If the covering oxide is also photoactive, the material can be self-cleaned when exposed to solar light. That is a big chemical challenge, because of many synthetic problems. Two different approaches were tested to solve this relevant issue. On one side, the hydrophobicity of ionic liquid modified SPES (sulfonated polyether sulfone) was combined with designed morphological features to confer superhydrophobicity. On the other side, the polymeric surface was covered with a transparent titania layer active in the near UV-region, able to mineralize organic molecules chemisorbed at the surface. Eventually, a different approach to modify oxidic (and not only) surfaces is the creation of a homogeneous layer of Ag nanoparticles by an innovative microwave procedure. That simple and accessible strategy allowed us to produce plasmonic surfaces (thanks to the dimension and the homogeneity of the Ag particles) with countless applications. The layer was shown to be a very active substrate for surface enhancement Raman spectroscopy (SERS). Thanks to the versatility of the synthetic method, all shapes and dimensions can be covered. That makes it a perfect candidate for the production of new generation of SERS sensors. The sensitivity towards molecules of environmental and biomedical interest was proved.

El deterioro de las construcciones realizadas a base de cemento, producido en gran medida, por la exposición de estas a la emisión de gases tóxicos emanados por el creciente parque automotor hace que se busquen alternativas a fin de contrarrestar su efecto sobre los elementos más expuestos.  Un nuevo método para afrontar este problema es la incorporación del fotocatalizador dióxido de titanio TiO2 capaz de desarrollar propiedades controladas por la luz solar como son la purificación del aire y la autolimpieza. Este trabajo busca introducir este componente orgánico al mortero de cemento usado para el tarrajeo de fachadas y elementos estructurales, para ello se adicionan diferentes porcentajes (5%,7.5% y 10%) de dióxido de titanio (TiO2) y se evalúan las propiedades de los morteros modificados haciendo uso de [1] para los ensayos de compresión, [2] para los ensayos de fluidez, [3]para los ensayos de absorción y [4] para los ensayos de actividad fotocatalítica. Este estudio concluye que el mejor porcentaje de adición de dióxido de titanio es de 5% con el cual se otorga al mortero de cemento la propiedad de autolimpieza sin perjudicar sustancialmente sus propiedades mecánicas.
The deterioration of the surfaces of the constructions made with mortar c/a 1: 5 of portland cement, are produced by being exposed to the emission of toxic gases emanating from the growing automobile fleet, this problem causes alternatives to be sought in order to counteract its effect on buildings and the environment. A new method to deal this problem is the incorporation of the titanium dioxide photocatalyst (TiO2) into the Portland cement mortar, which is capable of developing self-cleaning and air purification properties to be in contact with sunlight. This work seeks to introduce this organic component to the Portland cement mortar, used for the facade charging and structural elements, for this purpose, different percentages (5%, 7.5% and 10%) of titanium dioxide (TiO2) are added and the properties of the modified mortars making use of [1] compression tests, [2] fluidity tests, [3] absorption tests and [4] photocatalytic activity tests with which the self-cleaning capacity was verified. This study concludes that the best percentage of titanium dioxide addition is 5%, with which the portland cement mortar is granted self-cleaning property without substantially damaging its mechanical properties.
Tesis

Projeto de dissertação de mestrado em Engenharia Urbana
Agências governamentais gastam uma grande quantia do orçamento para melhorar a segurança, a fim de reduzir os acidentes rodoviários. Revestimentos superhidrofóbicos sobre misturas betuminosas estão sendo estudados para proporcionar repelência rápida da água e também efeitos de autolimpeza. Essas novas capacidades, superhidrofóbicas e autolimpantes, podem ser uma solução para se ter estradas mais seguras, removendo a água rapidamente e também removendo a sujidade. Desta forma, evita-se a formação de gelo e a aderência entre o pavimento e o gelo é reduzida, sendo mais eficiente que os métodos convencionais de remoção de gelo. Em outro contexto, devido à sua capacidade de degradar poluentes orgânicos como óleos e gorduras adsorvidas, as superfícies fotocatalíticas também são consideradas autolimpantes. Esta característica é de grande importância na segurança viária por evitar derrapagens causadas pela presença desses compostos. Ainda, os setores de transporte e de atividades industriais são as principais fontes que contribuem para a emissão de poluentes como os óxidos de azoto NOx (principalmente NO e NO2) e compostos orgânicos voláteis, que estão entre os mais perigosos, aumentando o risco de problemas respiratórios sendo altamente desejável a redução destes poluentes. Nesse sentido, o processo de oxidação avançada baseado no uso de materiais semicondutores demonstra alta eficiência na purificação de ar. Nesta investigação, as misturas betuminosas foram funcionalizadas com politetrafluoretileno (PTFE), em microescala, e dióxido de titânio (TiO2), em nano escala. O método camada por camada (LBL) foi utilizado para aplicar a resina epóxi, de metacrilato ou de poliuretano de modo a aderir as partículas de PTFE e TiO2 à superfície do pavimento. Um programa de ensaios experimentais foi desenvolvido e conduzido para avaliar o efeito de diferentes fatores incluindo o tipo de mistura (AC 6 e AC 10), a concentração de partículas de PTFE e TiO2, taxa de aplicação e tipos de resinas, e com base nisso se definir o melhor revestimento. As misturas betuminosas funcionalizadas foram caracterizadas pelo ângulo de contato da água (WCA), observação da formação de gelo, eficiência fotocatalítica, ensaio da fita-cola, ensaio do pêndulo britânico, ensaio de resistência à adesão ao gelo e avaliação da macrotextura por laser. Pelos resultados obtidos, pode-se concluir que a aplicação desses materiais sobre as misturas betuminosas foi realizada com sucesso, alcançando ou melhorando as novas capacidades.
Government agencies spend a large amount of the budget to improve safety in order to reduce road accidents. Superhydrophobic coatings are being studied over asphalt mixtures in order to provide fast water repelling and also self-cleaning effects. These new capabilities, superhydrophobic and self-cleaning ones, can be a solution to have safer roads by removing the water quickly and also cleaning the dirt particles. In this way, the ice formation is avoided and the adhesion between the pavement and the ice is reduced, being more efficient than the conventional ice removal methods. In another context, due to its ability to degrade organic pollutants such as oils, photocatalytic surfaces are also considered selfcleaning. This feature is of great importance in road safety by avoiding skidding caused by the presence of these compounds. In addition, the transportation and industrial sectors are the main sources of emission of pollutants such as NOx (mainly NO and NO2) and volatile organic compounds, which are among the most dangerous, increasing the risk of respiratory problems. Having said that, the reduction of these pollutants is highly desirable. In this sense, the advanced oxidation process based on the use of semiconductor materials demonstrates high efficiency in air purification. In this research, asphalt mixtures were functionalized by Polytetrafluorethylene (PTFE), in microscale, and Titanium Dioxide (TiO2), in nanoscale, for this purpose. The layer-by-layer method (LBL) was used to apply the epoxy, methacrylate or the polyurethane resin in order to adhere the PTFE and the TiO2 particles to the pavement surface. A program of experimental tests was developed and conducted to evaluate the effect of different factors including the type of blend, PTFE and TiO2 particle concentration and its application rate and the resin type for the purpose of finding the best superhydrophobic coating. The functionalized asphalt mixtures were characterized by the Water Contact Angle (WCA), Icing Observation, Photocatalytic Efficiency, Scotch Tape Test, British Pendulum Test, Ice Adhesion Strength Test and Evaluation of Macrotexture using Laser. By the results, it can be concluded that the application of these nano/micromaterials over asphalt mixtures was carried out successfully, achieving or improving the new capabilities.

Dissertação de mestrado integrado em Engenharia Civil
Atualmente, existe uma preocupação crescente acerca do esgotamento dos recursos naturais e do dano ao meio ambiente. A engenharia rodoviária em geral e particularmente o domínio dos pavimentos rodoviários pode contribuir de forma significativa para a mitigação destes problemas. A integração de nano/micromateriais nas misturas asfálticas que constituem as camadas superficiais dos pavimentos dotará essas superfícies de novas capacidades (funcionalização) particularmente em termos ambientais e em termos de segurança viária: (i) fotocatalíticas: capazes de fotodegradarem poluentes com o intuito de limparem o meio ambiente; (ii) superhidrofóbicas: melhor resistência à água e uma maior segurança rodoviária em períodos de chuva e de baixas temperaturas; (iii) autolimpantes: evitar problemas de derrapagem, facilitar a drenabilidade da água e dificultar o fenômeno da colmatação dos poros. Com o objetivo de dotar as superfícies dos pavimentos com estas novas capacidades funcionais, misturas asfálticas do tipo AC 6 e AC 14 foram funcionalizadas a partir da aspersão superficial dos semicondutores nano-TiO2 e/ou micro-ZnO. Previamente, a fim de avaliar o impacto químico e morfológico da aplicação dos semicondutores, foram realizados ensaios de Microscopia de Força Atômica (AFM) e Espectroscopia de Infravermelho Transformada de Fourier (FTIR) nos ligantes asfálticos usados para compor as misturas. A seguir, para verificar as novas capacidades, foram realizados ensaios de Ângulo de Contato e de Avaliação Fotocatalítica. Por fim, a melhor solução foi avaliada mecanicamente pela resistência à tração após o condicionamento por água para avaliar o impacto dos semicondutores. Os resultados indicam que houve um maior impacto superficial e químico pela técnica de aspersão da solução aquosa contendo ZnO. A combinação de TiO2 com ZnO promoveu propriedades fotocatalíticas, superhidrofóbicas e auto-limpantes, proporcionando a ambas as misturas asfálticas essas novas capacidades. Ademais a aspersão não causou impacto mecânico. Com o desenvolvimento dessas camadas, prevêem-se grandes benefícios para o ambiente e para a segurança rodoviária.
Presently, there is a growing concern about the depletion of natural resources and environmental damage. The road engineering in general and road pavements can contribute significantly to mitigate these problems. The integration of micro/nanoparticles in asphalt mixtures that compose the top layer of the pavements will provide their surfaces with new capabilities (functionalization) particularly in environmental and safety related terms: (i) photocatalytic: able to photodegrade pollutants for the purpose of cleaning the environment; (ii) superhydrophobic: better water resistance and better road safety in periods of rains and low temperatures; (iii) self-cleaning: avoid slipping problems, facilitate the water drainability and prevent the pore clogging phenomenon. In order to provide the new functional capabilities to the surface of the pavements, asphalt mixtures AC 6 and AC 14 were functionalized with superficial spraying of semiconductors nano-TiO2 and/or micro-ZnO. First, in order to evaluate the chemical and morphological impacts of the application of the semiconductors, tests of Atomic Force Microscopy (AFM) and Fourier Transform Infrared Spectroscopy (FTIR) onto the asphalt binder that compose the mixtures were carried out. Next, in order to verify the new capabilities, tests of Water Contact Angle and Photocatalytic Evaluation were carried out. Finally, the best solution was mechanically evaluated through Indirect Tensile Strength after immersion to analyze the impact of semiconductors. The results show that there was a higher superficial and chemical impact onto the bitumen by the spray technique of the ZnO aqueous solution. The combination of TiO2 and ZnO promoted photocatalytic, superhydrophobic and self-cleaning properties, providing the asphalt mixtures these new capabilities. Besides the spraying technique did not cause mechanical impact. With the development of these layers, benefits to the environment and road safety are foreseen.

Dissertação de mestrado integrado em Engenharia Civil
Os recentes desenvolvimentos nas áreas das nanociências e nanotecnologias estão a mudar o nosso mundo. O uso das nanopartículas pode tornar os nossos edifícios mais limpos, resistentes e fazer com que armazenem a energia solar para uso posterior. Com o intuito de contribuir para o desenvolvimento desta área, esta dissertação de mestrado tem como principal objetivo o estudo e desenvolvimento de uma argamassa de reboco exterior com capacidades térmicas e fotocatalítica. Com vista ao aumento do nível de sustentabilidade este estudo espera conferir às argamassas propriedades multifuncionais como a capacidade fotocatalítica, a função autolimpante e o melhoramento das capacidades térmicas. Neste trabalho vão ser analisadas argamassas de reboco exterior modificadas através da aspersão de uma solução aquosa de nanopartículas de TiO2 com concentração de 10 g/L e pH de 3 e de 8 sobre a sua superfície. Foram estudados dois traços, 1:1:6 e 1:2:9, com relações água/ligantes diferentes de forma a comparar as diferenças físicas e mecânicas de ambos, com e sem a aspersão de nanopartículas. De forma geral podemos concluir que a inclusão das nanopartículas de TiO2 de forma aspergida não produz variações significativas nas propriedades físicas e mecânicas das argamassas. Concluímos também que a técnica de aspersão utilizada garante o aprisionamento das nanopartículas na superfície da argamassa como pode ser comprovado pelos ensaios de SEM/EDS o que resulta em rendimentos de fotodegradação elevados. Os resultados obtidos com os ensaios térmicos são inconclusivos, não revelando melhoramento das capacidades térmicas das argamassas modificadas.
Recent developments in the areas of nano science and nano technologies are changing our world. The use of nanoparticles can make our buildings cleaner, resistant and have to store solar energy for later use. In order to contribute to the development of this area, this dissertation has as its main objective the study and development of an exterior plastering mortars with thermal and photocatalytic capabilities. In order to increase the level of sustainability this study hopes to give mortars multifunctional properties such as photocatalytic capacity, self-cleaning function and improving thermal capabilities. In this work are to be analyzed exterior plastering mortars modified by spraying an aqueous solution of TiO2 nanoparticles with concentration of 10 g / L and a pH of 3 and 8 on their surface. We studied two compositions, 1:1:6 and 1:2:9, with a different water/binder so as to compare differences in physical and mechanical properties, with and without spraying the nanoparticles. In general we can conclude that the inclusion of nanoparticles of TiO2 sprayed do not produce significant variations in physical and mechanical properties of mortars. We also conclude that the spraying technique used assures trapping nanoparticles in the surface of the mortar and be demonstrated by the tests of SEM / EDS resulting in high yields of photodegradation. The results obtained with the thermal tests are inconclusive, showing no improvement in the thermal capacities of the modified mortars.

Programa doutoral em Engenharia Civil
Atualmente, é crescente a preocupação com a poluição do ar, o esgotamento dos recursos naturais e, consequentemente com os danos impostos ao meio ambiente. Os pavimentos asfálticos precisam ser tecnicamente viáveis do ponto de vista mecânico, apresentar características funcionais adequadas em termos de conforto e segurança rodoviária e ser sustentáveis e de custo aceitável. Nesse contexto, o objetivo desta tese é desenvolver misturas asfálticas recicladas (ecológicas pela substituição parcial de material virgem) e com novas funções através da integração de nano/micropartículas para a camada superficial dos pavimentos. A integração de nano/micropartículas proporciona novas capacidades (funcionalização) às misturas asfálticas, nomeadamente fotocatalíticas, superhidrofóbicas e autolimpantes com um efeito adicional de antienvelhecimento dos ligantes asfálticos. Com o desenvolvimento da capacidade fotocatalítica, as misturas asfálticas são capazes de fotodegradar poluentes, melhorando assim a qualidade do ar. Sobre a capacidade superhidrofóbica, as misturas asfálticas funcionalizadas passam a repelir a água, proporcionando maior segurança rodoviária, principalmente em períodos de chuva e temperatura ambiental negativa. Com o efeito autolimpante, as misturas asfálticas funcionalizadas conseguem limpar poluentes, como partículas de sujidade, óleo e gordura, mitigando a diminuição do atrito devido à presença desses materiais na sua superfície. Para tanto, foi realizada uma extensa revisão bibliográfica para fundamentar esta tese de doutoramento. Em seguida, as misturas asfálticas foram funcionalizadas através de diferentes métodos de aplicação (incorporação em volume, modificação de ligante e revestimento por pulverização) e usando diferentes materiais (TiO2, ZnO e Politetrafluoroetileno). As novas propriedades e seus impactos foram analisados sob o ponto de vista mecânico, funcional e de funcionalização. As principais conclusões indicam que as misturas asfálticas podem ser funcionalizadas por esses materiais a fim de apresentarem novas capacidades, apresentando benefícios para o meio ambiente, sociedade, economia e também para o desempenho das misturas asfálticas.
Currently, there is a growing concern with air pollution, the depletion of natural resources, and, consequently, with the damage imposed on the environment. Asphalt pavements need to be technically viable from a mechanical point of view, present adequate functional characteristics in terms of comfort and road safety, be sustainable and at an acceptable cost. In this context, this thesis aims to develop recycled asphalt mixtures (ecological through the partial replacement of virgin material) and with new functions through the integration of nano/microparticles for the surface layer of asphalt pavements. The integration of nano/microparticles provides new capabilities (functionalization) to asphalt mixtures, namely photocatalytic, superhydrophobic, and self-cleaning with the additional anti-aging effect of asphalt binders. With the development of the photocatalytic capability, the asphalt mixtures are able to photodegrade pollutants, and therefore improving the air quality. Regarding the superhydrophobic capability, the functionalized asphalt mixtures start to repel the water, providing higher road safety, especially in periods of rain and negative environmental temperature. With the self-cleaning effect, the functionalized asphalt mixtures are able to clean pollutants, such as dirt particles, oil, and grease, over their surface, mitigating the decrease of friction due to the presence of these materials over their surface. Therefore, an extensive bibliographic review was carried out to support this doctoral thesis. Then, the asphalt mixtures were functionalized using different application methods (volume incorporation, modification of binder, and spraying coating) and using different materials (TiO2, ZnO, and Polytetrafluoroethylene). The new properties and their impacts were analyzed from mechanical, functional, and functionalization point of views. The main conclusions indicate that these materials can functionalize the asphalt mixtures to provide them with new capabilities, presenting benefits for the environment, society, economy, and for the performance of the asphalt mixtures.
FCT (SFRH/BD/137421/2018) and TECMINHO for the scholarships

碩士
國立臺灣科技大學
營建工程系
92
High rise buildings are more and more popular in the city and the clean task of the surface of the high rise buildings is also much more significant in the current time due to the effect on the environment. The conventional artificial cleaning method for the high rise buildings waste the resource of water and human resources. The self-cleaning ability of the nano coating on the surface of building has been proved. The great power of self-cleaning can induce the clean environment of the city automatically forever. The task of the research includes setting up the standard for the construction method and quality control for the coating of nano materials on the surface of building, the assessment of the economic efficiency by using this construction method, coating on a real scale building to investigate their real properties.

Dissertação de mestrado em Biofísica e Bionanossistemas
Nanocoatings applied in textile finishing are a very attractive way to add value to dayto- day products offering an interesting set of important and differentiated properties. The photocatalytic activity of titanium dioxide (TiO2) based nanomaterials for textile applications has been identified as a strategic vector with great industrial impact. The development of self-cleaning and antimicrobial surface finishes in common textiles has the potential to be used as a prophylactic measure to reduce the infection rates in hospitals as well as reduce the environmental impact of washing processes. In this research work Pulsed DC Magnetron Sputtering technique was used to deposit TiO2 thin films onto glass and Poly(lactic acid) (PLA) and cotton based substrates. On the other hand, TiO2 nanoparticles were also deposited on the textile surfaces by means of a dip-coating process. The main goal of the research work was the production of TiO2 - based functionalized textile substrates without changing its surface characteristics such as aesthetic and sensorial (e.g. touch feeling) properties. The applied textile finishing techniques in this research work need less to none of the solvents or surfactants commonly used in the industry leading to a cleaner production process reducing significantly the environment pollution. The samples were characterized by using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), Contact Angle measurements and UV – visible Spectroscopy techniques. The photocatalytic activity of the samples was studied by measuring the Methylene Blue (MB) degradation over time as a result of the catalyst exposure to ultraviolet (UV) radiation and its correlation with the initial concentration. This effect is directly correlated to the photocatalytic efficiency and rate of the samples. The self-cleaning activity was also evaluated by a wine stain removal test under UV light exposure.
Nanorevestimentos aplicados no processo de acabamento de materiais têxtil são uma forma muito atrativa para adicionar valor a produtos do quotidiano conferindo-lhes um conjunto de propriedades importantes e inovadoras. A atividade fotocatalítica dos nanomateriais à base de dióxido de titânio (TiO2) em aplicações têxteis tem sido identificado como um vetor estratégico com um elevado impacto industrial. O desenvolvimento de superfícies com acabamentos autolimpantes e antimicrobianos em têxteis comuns tem o potencial de ser utilizado como medida profilática na redução de taxas de infeção em ambientes hospitalares e reduzir o impacto ambiental relacionado com os processos de lavagem. Neste trabalho de investigação foi utilizada a técnica de pulverização catódica em magnetrão utilizando fonte DC pulsada para depositar filmes finos de TiO2 em substratos de vidro e de materiais têxteis baseados em ácido poliláctico (PLA) e algodão. Por outro lado, depositaram-se nanopartículas de TiO2 em substratos têxteis pela utilização de um processo de imersão. O principal objectivo do trabalho de investigação foi a produção de materiais têxteis com acabamentos de TiO2 sem que ocorresse a alteração das características superficiais tais como propriedades estéticas e sensoriais (e.g. sensação ao toque). As técnicas de acabamento superficial nos materiais têxteis utilizados neste trabalho de investigação utilizam uma quantidade inferior de solventes e tensioativos comparativamente com as normalmente utilizadas na indústria reduzindo, significativamente, a poluição ambiental. As amostras foram caracterizadas pela utilização das técnicas de Microscopia Electrónica de Varrimento (MEV), Microscopia de Força Atómica (MFA), medição do ângulo de contacto e Espectroscopia UV-Visível. A atividade fotocatalítica das amostras foi estudada inicialmente pela medição da degradação do Azul-de-metileno ao longo do tempo em resultado da exposição do catalisador à radiação ultravioleta (UV) e a sua correlação com a concentração inicial. Este efeito é diretamente correlacionado com a eficiência e velocidade fotocatalítica das amostras. A actividade autolimpante foi testada através de um teste de remoção de uma nódoa de vinho de um substrato têxtil funcionalizado com TiO2 exposto à luz UV sendo medido o valor de K/S correspondente ao longo do tempo de exposição.

碩士
中原大學
生物環境工程研究所
103
Membrane technology has widely used in various industries because of its high removal efficiency and compact treatment unit. However, as the operation time increases, accumulation of dissolved organic and inorganic constituents on membrane surface has promoted to aggravate the problem of membrane fouling. Membrane fouling deteriorates the permeability of the membrane and consequently increases operation pressure and increase energy consumption of the process. Membrane surface modification with catalyst semiconductors is proven as an effective method for fouling reduction. Hydroxyl radicals generated during photo excitation of catalyst surface by light is powerful to degrade organic compounds. Recently, numerous elements both metals and non-metal have been used to enhance energy adsorption of convention catalyst such as TiO2 and ZnO under visible light to prepare green catalyst. In this study, Ag2CO3/TiO2 composite catalyst was prepared by a simple co-precipitation of pristine TiO2 (Degussa, P25) with AgNO3 and Na2CO3 under room temperature of 25 ± 2 ºC. Effect of TiO2 loading on the photocatalytic degradation of reactive black 5 dye under visible light (40 W halogen lamp) were evaluated. The results showed that 60 w/w% of TiO2 have the best performance in photocatalytic test with the color removal efficiency of xx in 5 h. With this result, the catalyst of 60 w/w.% TiO2 at different mass volume of 1 g, 2 g and 4 g was loaded on commercial Polyvinyliden fluoride (PVDF) membrane sheets, which its surface were preliminary treated by plasma graft polymerization with poly(acrylic acid). Membrane surface morphology and polarity of membrane were characterized using a scanning electron microscope and a contact angle measurement, respectively. Antifouling performance of membranes was carried out using several test solutions including (i) Bovine Serum Albumin (BSA), (ii) alginate acid and (iii) secondary effluent wastewater from municipal wastewater treatment plant. Obviously, Ag2CO3/ TiO2 enhanced hydrophilicity of membrane with a significant reduction of contact angle from 121º to 0º. In the antifouling test, water flux rapidly decreased for all membranes after it was fitered with test solutions. The membrane with 2 g catalyst loading showed the best antifouling property for BSA and alginate acid with water flux recovery rate of 94% and 95%, respectively at the irradiation time of 60 min. Interestingly, the highest water recovery rate with 59% was found for secondary effluent wastewater at the lowest catalyst loading of 1g. It is unclear yet what factors have played important role in this result. It might be related to a complexicity of feed wastewater or the increase of membrane surface roughness with increasing catalyts load. To confirm these results, a long-term test is required with a better instument analysis.

Atualmente assiste-se a um grave problema de salubridade visual das cidades, designadamente no espaço edificado/ construído. A sujidade é uma ameaça que, junto com os graffitis, tem contribuído para a degradação precoce dos espaços urbanos. A fim de se enfrentar este problema, que tem vindo a proliferar nas cidades, um pouco por todo o mundo, a presente dissertação de mestrado ambiciona contribuir para a sistematização da informação existente sobre a produção e caracterização de argamassas de auto-limpeza. As argamassas de auto-limpeza são produzidas por uma de duas formas: com a adição de nanopartículas de dióxido de titânio (TiO2) na sua matriz ou com a aplicação de um filme fino à base de TiO2 na sua superfície. Esta segunda é apontada como a técnica mais eficaz e económica. Salienta-se o facto do TiO2 ser um dos nanomateriais mais utilizados na construção pelas suas propriedades fotocatalíticas que o capacitam como um dos mais exímios fotocatalisadores, aquando da fotocatálise heterogénea. É graças ao processo de fotodegradação química da fotocatálise, que na presença de luz solar e da ação da água, que o TiO2 é ativado, desencadeando reações químicas que aumentam a eficácia e eficiência fotocatalítica. Analisou-se um conjunto de trabalhos de investigação recentes que comprovam que o uso das argamassas de auto-limpeza é adequado e benéfico em intervenções em edifícios novos como em obras de conservação e reabilitação de edifícios antigos. Além de reduzirem os investimentos em obras de limpeza, manutenção/conservação e reabilitação, prolongam a conservação das fachadas e melhoram os níveis da qualidade do ar. Apesar do crescente número de patentes pedidas e concedidas nesta área, as normas aplicáveis ainda não se encontram uniformizadas. Nesse sentido, a experiência do Japão deve ser tida como exemplo para que os restantes países desenvolvam de forma consensual as suas próprias normas e patentes, permitindo, futuramente, conferir maior credibilidade, segurança no uso dos nanomateriais e uma maior permeabilidade no setor da construção. Elencam-se alguns nano-produtos à base de nano TiO2 comercializados que têm vindo a ser aplicados sobretudo na China, Japão e na Alemanha.
Currently we are witnessing a serious problem of visual health of cities, particularly in the built/ constructed space. The dirt is a threat that, along with the graffiti, have contributed to premature deterioration of urban areas. In order to tackle this problem, which has been proliferating in cities all over the world, this master thesis aims to contribute to the systematization of existing information about the production and characterization of self-cleaning mortars. The self-cleaning mortars are produced by one of two ways: with the addition of titanium dioxide (TiO2) nanoparticles in the matrix or with the application of a thin film based on TiO2 on its surface. The second is considered the most effective and economical technique. It should be noted that the TiO2 is one of the most used nanomaterials in construction due to its photocatalytic properties which also enable one of the most eximious photocatalysts, when heterogeneous photocatalysis. It is thanks to chemical photodegradation process of photocatalysis, in the presence of sunlight and water action, the TiO2 is activated, triggering chemical reactions that increase efficiency and photocatalytic efficacy. A number of recent research were analyzed, showing that the use of self-cleaning mortars is suitable and beneficial in interventions in new buildings as in conservation and rehabilitation works of old buildings. In addition to reducing investment in cleaning works, maintenance/ conservation and rehabilitation, these mortars extend the facades conservation and improve air quality levels. Despite the growing number of requested and granted patents in this area, applicable rules are not yet standardized. In this regard, Japan's experience should be taken as an example for other countries to develop by consensus its own standards and patents, allowing in the future give more credibility, safety in the use of nanomaterials and increased its permeability in the construction sector. Some commercial nano-TiO2 based products are listed and applications are presented (in China, Japan and in Germany).

碩士
國立臺灣科技大學
營建工程系
92
This Study simulates the ability to dissolve the organism of TiO2 photocatalysis sprayed on outdoor glass surface that polluted by organism. This study can be differentiated to indoor-experiment, outdoor-experiment and compare between indoor and outdoor experiment. Ultraviolet intensity variants can be divided into 10μW/cm2,1000μW/cm2 and 3000μW/cm2 to compare with different weather. Spray layer variants can be divided into one-layer, two-layers and three-layers. Organism’s concentration variants can be divided into red ink that diluted to 10X and 30X. By search, when ultraviolet intensity increased, photocatalysis’s self-cleaning ability will increase, but its increase effect is not direct proportion of ultraviolet intensity. When ultraviolet intensity is higher, less increase effect will show. In different spray layer states, we find that although increase spray layer can increase self-cleaning ability, but it’s uneconomic. In different concentration states, we find that when concentration is higher, its dissolve ability is better than lower.