In this work, a series of simple, rapid and effective photoelectrochemical methodologies have been developed and successfully applied to the study of kinetic and thermodynamic characteristics of photocatalytic oxidation processes at TiO2 nanoparticulate films. As an application of the systematic studies of photocatalytic processes by photoelectrochemical techniques, a rapid, direct, absolute, environmental-friendly and accurate COD analysis method was successfully developed. In this work, the TiO2 nanoparticles colloid was prepared by the sol-gel method. The TiO2 nanoparticles were immobilized onto ITO conducting glass slides by dip-coating method. Thermal treatment was carried out to obtain nanoporous TiO2 films of different structures. At low calcination temperature (below 600°C), nanoporous TiO2 films of pure anatase phase were prepared. At high calcination temperature (above 600°C), nanoporous TiO2 films of mixed anatase and rutile phases were obtained. At these film electrodes, the work was carried out. By employing steady state photocurrent method and choosing phthalic acid as the model compound, the photocatalytic activity of the TiO2 nanoporous films calcined at various temperatures and for different lengths of time was evaluated. It was found that the films with mixed anatase and rutile phases calcined at high temperature exhibited high photocatalytic activity. Based on semiconductor band theory, a model was proposed, which explained well this finding. By employing linear sweep voltammetry (under illumination) and choosing glucose (an effective photohole scavenger) as a model compound, the characteristics of the photocatalytic processes at nanoparticulate semiconductor electrodes were investigated. Characteristics of the nanoporous semiconductor electrodes markedly different from bulk semiconductor electrodes were observed. That is, within a large range of electrode potentials above the flat band potential the electrodes behaved as a pure resistance instead of exhibiting variable resistance expected for bulk semiconductor electrodes. The magnitude of the resistance was dependent on the properties of the electrodes and the maximum photocatalytic oxidation rate at TiO2 surface determined by the light intensity and substrate concentration. A model was proposed, which explained well the special characteristics of particulate semiconductor electrodes (nanoporous semiconductor electrodes). This is the first clear description of the overall photocatalytic process at nanoparticulate semiconductor electrodes. The investigation set a theoretical foundation for employing photoelectrochemical techniques to study photocatalytic processes. By using the transient technique (illumination step method analogous to potential step method in conventional electrochemistry), the adsorption of a number of strong adsorbates on both low temperature and high temperature calcined TiO2 nanoporous films was investigated. Similar adsorption characteristics for different adsorbates on different films were observed. In all the cases, three different surface bound complexes were identified, which was attributed to the heterogeneity of TiO2 surface. The photocatalytic degradation kinetics of the pre-adsorbed organic compounds of different chemical nature was also studied by processing the photocurrent-time profiles. Two different photocatalytic processes, exhibiting different rate characteristics, were observed. This was, again, attributed to the heterogeneity of the TiO2 surface corresponding to heterogeneous adsorption characteristics. The catalytic first order rate constants of both fast and slow processes were obtained for different organic compounds. It was found that for different adsorbates of different chemical nature the magnitudes of rate constant for the slow kinetic process were very similar, while the magnitudes of rate constant for the fast process were significantly affected by the photohole demand characteristics of different adsorbates. Photohole demand distribution that depends on the size and structure of the adsorbed molecules was believed to be responsible for the difference. By employing steady state photocurrent method, the photocatalytic degradation kinetic characteristics of both strong adsorbates and weak adsorbates of different chemical structures were compared at pure anatase TiO2 nanoporous TiO2 films as well as at anatase/rutile mixed phase TiO2 nanoporous film electrodes. At the former electrodes for all the different organic compounds studied, the photocatalytic reaction rate increased linearly with concentration at low concentrations. Under such conditions, it was demonstrated that the overall photocatalytic process was controlled by diffusion and was independent of the chemical nature of organic compounds. However, the linear concentration range and the maximum photocatalytic reaction rate at high concentrations were significantly dependent on the chemical nature of the substrates. This was explained by the difference in the interaction of different organic compounds with TiO2 surface, the difference in their photohole demand distributions at the TiO2 surface and the difference in their nature of intermediates formed during their photocatalytic mineralization. In contrast, at the latter electrodes for the photocatalytic oxidation of different organic compounds the linear ranges (diffusion control concentration range) and the maximum reaction rates at high concentration were much larger than at the former electrodes and much less dependent on the chemical nature of the organic compounds. The spatial separation of photoelectrons and photoholes (due to the coexistence of rutile phase and anatase phase) and the increase in the lifetime of photoelectrons and photoholes are responsible for the excellent photocatalytic activity of the electrodes. By employing the thin-layer photoelectrochemical technique (analogous to the thin-layer exhaustive electrolytic technique), the photocatalytic oxidation of different organic compounds at the mixed phase TiO2 nanoporous electrodes were investigated in a thin layer photoelectrochemical cell. It was found that the charge derived from exhaustive oxidation agreed well with theoretical charge expected for the mineralisation of a specific organic compound. This finding was true for all the compounds investigated and was also true for mixtures of different organic compounds. The photocatalytic degradation kinetics of different organic compounds of different chemical identities in the thin layer cell was also investigated by the photoelectrochemical method. Two kinetic processes of different decay time constants were identified, which were attributed to the degradation of preadsorbed compounds and the degradation of compounds in solution. For the degradation of compounds in solution, a change in the overall control step from substrate diffusion to heterogeneous surface reaction was observed. For different organic compounds, the variation of the rate constant was determined by the photohole demand rather than by the chemical identities of substrates. The kinetics of the fast kinetic process, on the other hand, was greatly affected by the adsorption properties of the substrates. For the strong adsorbates, the rate was much larger than for weak adsorbates. However, the rate constant of the process was independent of the chemical identities of the substrates and the variation of the constant was also determined by the photohole demand. Based on the principles of exhaustive photoelectrocatalytic degradation of organic matter in a thin layer cell, a novel, rapid, direct, environmental-friendly and absolute COD analysis method was developed. The method was tested on synthetic samples as well as real wastewater samples from a variety of industries. For synthetic samples with given compositions the COD values measured by my method agree very well with theoretical COD value. For real samples and synthetic samples the COD values measured by my method correlated very well with those measured by standard dichromate COD analysis method.

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.

This study applied sputtering technology to prepare composite film photocatalyst TiO2/ITO for investigating the decomposition efficiency of acetone using composite TiO2/ITO made by single- and multi-layer processes. The influences of operating parameters, including sputtering operating parameters and photocatalytic operating parameters, on the decomposition efficiency of acetone were further investigated. Operating parameters investigated for the sputtering process included oxygen to argon ratio (O2/Ar), temperature, substrate, sputtering dutation, and sputtering layers, while operating parameters investigated for the photocatalytic decomposition of acetone included light wavelength, H2O concentration, O2 concentration, initial acetone concentration, and the type of photocatalysts. In the experiments, acetone was degraded by the composite film photocatalyst TiO2/ITO in a self-designed batch photocatalytic reactor. Operating parameters included light wavelength (350~400 nm, 435~500 nm, 506~600 nm), the type of photocatalysts (single-layer film photocatalyst TiO2/ITO with the thickness of 355.3, 396.6, 437.5, 487.5, and 637.5 nm; double- and triple-layer TiO2/ITO), H2O concentration (0, 50, 100, 200, and 300 ppm). The incident light with different wavelength irradiated with three 15-W lamps of near UV light or LED lamps of blue and green lights placed on the top of the photocatalytic reactor. Acetone was injected into the reactor by using a gasket syringe and vaporized for further photocatalytic degradation on the film photocatalyst TiO2/ITO placed at the bottom of the reactor. Air samples were taken to analyze acetone concentration with a GC/FID. The composite film photocatalyst TiO2/ITO was mainly composed of anatase with a few rutile. The thicknesses of the single- and IV double-layer film photocatalyst with the thickness of 473.5 nm and 506.0 nm, respectively. Experimental results indicated that the highest decomposition efficiency of acetone was obtained by using TiO2/ITO, followed by TiO2/ground glass and TiO2/glass. The highest decomposition efficiency of acetone was observed by using TiO2/ITO at 50¢XC, 20% O2, and 100 ppm H2O. In the kinetic model, the acetone decomposition of single-layer TiO2/ITO was zero-order reaction. The acetone decomposition of double-layer TiO2/ITO in high initial acetone concentration was zero-order reaction, while that in low initial acetone concentration was first-order reaction. Thus, the decomposition of acetone exerted by TiO2 film photocatalyst can be enhanced efficiently by ITO. Under the incidence of blue light, the reaction rate of acetone decomposition were 2.353¡Ñ10-5 and 3.478¡Ñ10-5 £gmole/cm2-s for using single- and double-layer TiO2/ITO, respectively. Finally, a bimolecular Langmuir-Hinshelwood (L-H) kinetic model was applied to simulate the influences of initial acetone concentration, temperature, and relative humidity on the promotion and inhibition for the photocatalytic degradation of acetone. This study revealed that the L-H kinetic model could successfully simulate the photocatalytic reaction rate of acetone.

In the first part of the study, birchwood xylan-lignin film formation was studied. After film forming effect of lignin on pure birchwood xylan was demonstrated, the minimum lignin concentration necessary to form films was determined as 1.1% (lignin/xylan). So, it was determined that keeping about one percent lignin in xylan (w/w) was sufficient for film formation. Biodegradability of the lignin-birchwood xylan composite films was investigated enzymatically using 0.21 U / ml xylanase in an accelerated test. All the films containing lignin were hydrolyzed by xylanase showing biodegradability of the films. Colors of the birchwood xylan-lignin composite films containing different lignin concentrations were compared. Deviations of the color from the reference color were similar between the films. In the second part of the study, photocatalytic antimicrobial film production was investigated on wheat gluten-based films. In order to produce antimicrobial films, wheat gluten films were coated with a semiconductor, titanium dioxide (TiO2), applying different procedures. Coated films were illuminated and photocatalytical inactivation of Escherichia coli on films were determined by antimicrobial tests. The coating procedure in which titanium dioxide (TiO2) was produced from titanium tetraisopropoxide (TTIP) in aqueous-nitric acid and aqueous-hydrochloric acid solutions gave the best antimicrobial result but the films turned out to be deformed and brittle. Spreading TiO2 sol-gel on semi-dried wheat gluten films resulted in flexible and undeformed films having about 40% antimicrobial activity.

This study investigated the feasibility of glassfiber filter coated with titanium dioxide (TiO2) on removing indoor VOCs using photocatalytic technology, which could further expand the electronic filter¡¦s function . First of all, we coated the titanium dioxide (TiO2) photocatalysts on the glassfiber filter with chemical vapor desposition (CVD) method, then dried it at 120¢J, and calcined it to prepare a nano-sized TiO2 coated filter . Secondly, we collected VOC samples in a printery and analyzed their chemical components. The main components of VOCs (benzene¡Btoluene and acetone) were then conducted in a self-designed laboratory-scaled batch photocatalytic reactor. The decomposition of acetone for different operating parameters, including initial VOC concentration, CVD coating time, and calcination temperature, was further conducted. Besides, a nano-sized photocatalyst indoor air purifier was self-designed for this particular study. The air purifier consists of a set of near-UV light source, a nano-sized photocatalyst glassfiber filter, a stainless shelter, and a circulating fan. The air purifier was tested to ascertain its capability on the removal of indoor VOCs in a well-tight environmental chamber. The testing results indicated the nano-sized photocatalyst glassfiber filter can be used to remove indoor VOCs . In the final stage, a nano-sized TiO2 photocatalyst electronic air cleaner was self-designed for this particular further study in a printery. The air cleaner consists of a set of UV light source, a nano-sized photocatalyst glassfiber filter, a set of electronic filter, carborn filter and a pain coated steel plate shelter. The air cleaner was tested to ascertain its capability on the removal of indoor VOCs in a return air channel of air condition system. The testing results indicated that the nano-sized photocatalyst glassfiber filter can be used to remove indoor VOCs

In order to obtain sustainable engineering systems, this research investigates surface and interface properties of metals and active nanostructured coatings. The goal is to develop new approaches in order to improve the corrosion resistance and obtain knowledge in reconstruction of worn and/or corroded surfaces. The research will focus on high carbon steels as the substrate. These materials are used in most of industries and vehicles like aircrafts and automobiles. For anti-corrosion and self-healing applications, the layer-by-layered (LBL) coatings consisting photo-catalytic materials, the corrosion inhibitor, and the polyelectrolyte will be studied. Potential dynamic tests will be carried out in order to characterize the corrosion potential and current. For wear study, we will develop a metallic composite that has several functions, such as corrosion and wear protection, refresh or reverse worn or corroded surface. Characterization techniques used include optical microscope, surface interferometer, tribometer and the hardness tester. The ultimate goal of this research is to understand several types of problems on metal surface, such as corrosion and wear, and explore the possible ways to reduce those by using active nano-structured composite coating on metal surface.

Pollution created by textile dyeing operations attracts significant attention because an effluent containing a complex mixture of coloured and potentially toxic compounds can be released with the discharged water. Developing dyes and dyeing conditions to reduce the amount of residual dye contained in any effluent has been one of many approaches to minimise this environmental impact. However, the presence of coloured discharge cannot be totally eliminated using only this strategy. Thus, development of efficient post-dyeing wastewater treatment methods capable of removing coloured products from the water is of paramount importance. TiO2-mediated photocatalytic degradation of organic dye molecules via oxidation is the focus of the study reported in this thesis. TiO₂ significantly increases the rate of photodegradation of a wide range of organic dyes under mild operating conditions, and is able to mineralise a wide spectrum of organic contaminants. TiO₂ is also one of the very few substances appropriate for the industrial applications. One of primary aims of this thesis is to test the hypothesis that augmenting standard TiO₂ photocatalysts with Au nanoparticles could increase performance of a catalyst, while immobilizing TiO₂ on SiO₂ support may improve the cost of the process efficiency, i.e. more photocatalytic degradation per particle of TiO₂. Combining TiO₂ doped with gold nanoparticles on SiO₂ support has the potential to provide the highest photocatalytic ability at the lowest cost. The first half of the thesis is concerned with establishing and optimizing experimental conditions for monitoring photodegradation via UV-Visible spectroscopy. Effects of various conditions such as temperature, sequence of addition of reagents, exposure to light vs. experiments in dark, sampling methods, and the use of quenching agent were examined. The main conclusions from this study are that light-induced photodegradation using titanium dioxide nanoparticles catalysts is comparatively more efficient than purely chemical catalytic (e.g. non-light mediated) degradation, even if the latter is performed at elevated temperature. Further, the rate of dye degradation is affected considerably by the parameters of the system. The degradation rate depends strongly on the pH of the solution, due to charges on both the catalyst surface and in the dye. In general, at pH ≤ 6.8, which is the zero charge point for TiO₂, reactions proceeded faster than those at higher pH. Six dyes from four different classes of dyes used in industry were used in this study, and all showed different photodegradation behaviour. The second half of thesis tests the photocatalytic abilities of various TiO₂-based catalysts: pure TiO₂ (commercial and custom-made in our laboratory), TiO₂-supported gold nanoparticles (Au/TiO₂), SiO₂-supported TiO₂ (TiO₂/SiO₂), and SiO₂-supported Au/TiO₂. The best photocatalytic performance was observed for the custom-made TiO₂ code-named as e-TiO₂, which was synthesized using the sol-gel method in dry ethanol. TiO₂-supported Au55 nanoparticles showed a similar level of catalytic ability but are significantly more expensive. It was observed that dye adsorption played a significant role in the case of SiO₂-immobilized photocatalysts.

Made available in DSpace on 2014-12-17T14:07:15Z (GMT). No. of bitstreams: 1 MaraTST_DISSERT.pdf: 2071273 bytes, checksum: 9636b6602dd1a469f78b17d077ba757f (MD5) Previous issue date: 2013-03-04 / In recent decades have seen a sharp growth in the study area of nanoscience and nanotechnology and is included in this area, the study of nanocomposites with self-cleaning properties. Since titanium dioxide (TiO2) has high photocatalytic activity and also antimicrobial, self-cleaning surfaces in your application has been explored. In this study a comparison was made between two synthesis routes to obtain TiO2 nanoparticles by hydrothermal method assisted by microwave. And after analysis of XRD and SEM was considered the best material for use in nanocomposites. It was deposited nanocomposite film of poly (dimethyl siloxane) (PDMS) with 0.5, 1, 1.5 and 2% by weight of nanoparticles of titanium dioxide (TiO2) by the spraying method. The nanocomposite was diluted with hexane and the suspension was deposited onto glass substrate, followed by curing in an oven with forced air circulation. The photocatalytic activity of the nanocomposite impregnated with methylene blue was evaluated by UV- vis spectroscopy from the intensity variation of absorption main peak at 660nm with time of exposure to the UV chamber. Changes in the contact angle and microhardness were analyzed before and after UV aging test. The effect of ultraviolet radiation on the chemical structure of the PDMS matrix was evaluated by spectrophotometry Fourier transform infrared (FTIR).The results indicated that the addition of TiO2 nanoparticles in the coating PDMS gave high photocatalytic activity in the decomposition of methylene blue, an important characteristic for the development of self-cleaning coatings / Nas ?ltimas d?cadas tem-se observado um crescimento acentuado no estudo da ?rea de nanoci?ncia e nanotecnologia em que inclui-se nessa ?rea, o estudo de nanocomp?sitos com propriedades autolimpantes. Desde que o di?xido de tit?nio (TiO2) apresenta alta atividade fotocatal?tica e tamb?m, atividade antimicrobiana, sua aplica??o em superf?cies autolimpantes tem sido amplamente explorada. Neste trabalho foi feito uma compara??o entre duas rotas de s?ntese para obten??o de nanopart?culas de TiO2 pelo m?todo hidrot?rmico assistido por micro-ondas. Ap?s an?lise de DRX e MEV foi analisado o melhor material para aplica??o em nanocomp?sitos. Foram depositados filmes de nanocomp?sito de poli(dimetil siloxano) (PDMS) com 0,5, 1, 1,5 e 2% em massa de nanopart?culas de di?xido de tit?nio (TiO2) pelo m?todo de aspers?o. O nanocomp?sito foi dilu?do em hexano e a suspens?o foi depositada sobre l?minas de vidro, seguida de cura em estufa com circula??o for?ada de ar. A atividade fotocatal?tica do nanocomp?sito impregnado com azul de metileno foi avaliada pela t?cnica de espectroscopia de UV-V?sivel, a partir da varia??o da intensidade de absor??o do pico principal a 660 nm com o tempo de exposi??o em c?mara UV. Altera??es no ?ngulo de contato e na microdureza foram analisadas antes e ap?s o ensaio de envelhecimento UV. O efeito da radia??o ultravioleta na estrutura qu?mica da matriz de PDMS foi avaliado por espectrofotometria no infravermelho por transformada de Fourier (FTIR). Os resultados indicaram que a adi??o das nanopart?culas de TiO2 em PDMS conferiram ao revestimento boa atividade fotocatal?tica na decomposi??o do azul de metileno, caracter?stica importante para o desenvolvimento de revestimentos autolimpantes

La dépollution est aujourd’hui un enjeu majeur pour la protection de l’environnement et un développement durable. Les technologies membranaires et les procédés d’oxydation avancée jouent un rôle de plus en plus important dans le traitement de l'eau que ce soit pour la production d’eau potable que pour le traitement des eaux usées urbaines ou industrielles. La photocatalyse hétérogène est un procédé d’oxydation avancée permettant la génération des espèces très oxydantes comme les radicaux OH•, en présence d’eau et de dioxygène, lors de l’irradiation de certains solides semi-conducteurs au premier rang desquels on retrouve le dioxyde de titane. L’objectif final visé dans cette thèse est le développement de filtres photocatalytiques performants mis en œuvre dans des procédés hybrides couplant séparation et photodégradation. Le mode d’élaboration envisagé pour ces filtres photocatalytiques est basé sur une voie de synthèse en rupture utilisant un polymère biosourcé, la cellulose, à la fois comme réactif (source d’oxygène) et support mécanique pour la croissance de nanoparticules de TiO2 à partir de tétrachlorure de titane. La première partie de la thèse est dédiée à une revue bibliographique qui porte principalement sur les procédés membranaires et hybrides, le dioxyde de titane et ses propriétés photocatalytiques et sur les propriétés chimiques, structurales et microstructurales et l’évolution thermique de la cellulose. Après un descriptif des matériels et méthodes mis en œuvre dans l’étude expérimentale sont d’abord présentés et discutés les résultats obtenus sur la préparation et la caractérisation de poudres purement minérales, à base de TiO2, et de poudres composites TiO2-carbone. L’effet du dopage du TiO2 par différents métaux de transition afin d’améliorer ses propriétés fonctionnelles est ensuite examiné. Une simplification du procédé de synthèse consistant à éliminer tout usage de solvant est exposée dans le chapitre suivant. S’appuyant sur le savoir-faire précédemment acquis en matière de synthèse et sur les performances photocatalytiques préalablement mesurées, le dernier chapitre est consacré aux travaux préliminaires menés sur la préparation de filtres photocatalytiques et sur l’évaluation leurs performances fonctionnelles. / The pollution is definitely a major issue for environmental protection and sustainable development. Membrane technologies and advanced oxidation processes play more and more a key-role in the treatment of water both for the production of drinking water and for the treatment of municipal and industrial wastewaters. Heterogeneous photocatalysis is an advanced oxidation process for generating highly oxidizing species such as OH• in the presence of water and dioxygen, under irradiation of some semiconducting solids like titania (TiO2). The targeted objective for this PhD work is the development of efficient photocatalytic filters to be implemented in hybrid processes coupling separation and photodegradation. The innovative route investigated for preparing such photocatalytic filters is based on the use of a bio-based polymer, i.e. the cellulose, both as reactant (oxygen source) and mechanical support for the growth of titania nanoparticles from titanium tetrachloride. The first part of the thesis is dedicated to a literature review mainly focused on membrane and hybrid processes, on titanium dioxide and its photocatalytic properties and on the chemical, structural, microstructural and thermal behaviour of cellulose. After a description of the experimental procedures, the second part of this manuscript is first dedicated to the presentation and the discussion of the experimental results on the preparation and characterization of pure titania powders and of TiO2-carbon composite powders. The effect of titania doping by different transition metals in order to improve its functional properties is then examined. Simplification of the synthesis process by removing any is described in the next chapter. From the previously developed know-how on synthesis and photocatalytic performance, the last chapter is devoted to preliminary work on the preparation of photocatalytic filters and on the assessment of their functional properties.

A oxidação fotocatalítica do glicerol (OFG) é uma possível alternativa para aproveitamento do excedente de glicerol proveniente do processo de produção do biodiesel, porém são poucos os registros desta reação na literatura. Neste trabalho, primeiramente foram testadas amostras comerciais de ZnO e TiO2, com o objetivo de identificar e quantificar os principais produtos de oxidação para cada semicondutor. Também foram realizados testes para determinação da influência dos parâmetros reacionais sobre a conversão e seletividade para gliceraldeído (GAD) e dihidroxiacetona (DHA), variando-se as condições experimentais tanto isoladamente quanto simultaneamente, através planejamento de experimentos. Por fim, foram sintetizadas amostras de ZnO visando-se obter uma amostra com melhores resultados em termos de conversão e seletividade para GAD e DHA que a amostra comercial. Os testes fotocatalíticos foram conduzidos em reator batelada (slurry) sob radiação ultravioleta, usando soluções aquosas de glicerol. Os produtos de oxidação foram analisados por cromatografia líquida de alta eficiência (CLAE). Os catalisadores sintetizados foram caracterizados por MEV, área BET, DRX, espalhamento de raios X a baixo ângulo e medidas de Potencial Zeta. Os resultados mostraram que ZnO e TiO2 diferem significativamente quanto à seletividade. O ZnO apresentou maior seletividade para produtos de maior valor agregado, como o gliceraldeído (GAD) e a dihidroxiacetona (DHA), indicando maior contribuição da fotocatálise indireta. O TiO2 apresentou seletividade maior para produtos resultantes da quebra da molécula de glicerol, como o formaldeído e o glicolaldeído, o que indica maior contribuição da fotocatálise direta. Nos testes da influência dos parâmetros reacionais para o ZnO, determinou-se que a conversão é afetada principalmente pelo pH inicial e concentração de catalisador e que a seletividade é afetada principalmente pela temperatura de reação e pH inicial. Em relação às amostras de ZnO sintetizadas em laboratório, nenhuma foi mais fotoativa que a amostra comercial, porém a amostra ZnO-B foi a mais fotoativa dentre as sintetizadas e foi mais seletiva ao GAD do que o ZnO comercial. Pôde-se determinar que o potencial zeta foi a característica mais influente na fotoatividade destes catalisadores, sendo que quanto mais positivo este valor, mais fotoativo o catalisador. Finalmente, em relação às amostras de ZnO com diferentes proporções de planos polares, a amostra com baixa proporção foi cerca de 2 vezes mais fotoativa que a amostra com alta proporção destes planos, o que se opõe aos resultados encontrados na literatura sobre fotoatividade relacionada a planos cristalinos. / The photocatalytic oxidation of glycerol emerges as a potential alternative to contribute to the utilization of glycerol surplus from biodiesel production. However, there are few reports about this reaction in the literature. In this work, as a first approach, commercial samples of ZnO and TiO2 were tested in order to identify the main products for each semiconductor. Next, the influence of the reaction parameters on the conversion and selectivity to glyceraldehyde (GAD) and dihydroxyacetone (DHA) was studied through a design of experiments, using ZnO as catalyst. Finally, additional ZnO samples were synthesized as an attempt to obtain a catalyst with conversion and/or selectivity higher than the commercial sample. The photocatalytic tests were carried out in a batch reactor (slurry) under ultraviolet radiation, using aqueous solution of glycerol. The oxidation products were analysed by liquid chromatography (HPLC). The synthesized catalysts were characterized by SEM, BET surface area, XRD, SAXS and Zeta Potential measurements. The results showed that ZnO and TiO2 differ significantly in selectivity. ZnO was more selective to products with higher commercial value (GAD and DHA), indicating greater contribution from indirect photocatalysis. On the other hand, TiO2 showed higher selectivity to products from the cleavage of the glycerol molecule, such as formaldehyde and glycolaldehyde, which indicates greater contribution from direct photocatalysis. In reference to the tests about the influence of the reaction conditions using ZnO, it was found that conversion was affected mainly by the initial pH and catalyst concentration, whereas selectivity was affected mainly by the temperature and initial pH. Regarding the synthesized ZnO catalysts, none of them reached conversion higher than the commercial sample, yet the sample ZnO-B showed the highest selectivity to GAD, even higher than the commercial sample. It was also determined that the zeta potential was the most influential characteristic on the catalyst activity. Finally, regarding the ZnO catalysts with different proportions of polar planes, the sample with low proportion of polar planes was about 2 times more active than the sample with high proportion of polar planes, which contradicts the records found in the literature about this specific topic.