Η φωτοκαταλυτική παραγωγή H2 μέσω διεργασιών φωτοκαταλυτικής αναμόρφωσης, μελετήθηκε με χρήση νανοκρυσταλλικών υμενίων TiO2 εμπλουτισμένων με εναποτεθειμένα μέταλλα στην επιφάνειά τους. Το TiO2 παρασκευάστηκε με τη μέθοδο sol-gel παρουσία οξικού οξέος και ενός επιφανειακώς δραστικού μορίου, του Triton X-100. Τα υμένια που παρασκευάστηκαν ήταν κρυσταλλικής μορφής ανατάση, με μέσο μέγεθος των σωματιδίων 12 nm, αρκετά σημαντικές υδροφιλικές ιδιότητες και υψηλή προσροφητική ικανότητα, ενώ είναι και πολύ ικανοί φωτοκαταλύτες για την αντίδραση διάσπασης των προσροφημένων χρωστικών στην επιφάνειά τους. Η μελέτη της αντίδρασης παραγωγής H2 πραγματοποιήθηκε με χρήση του φωτοκαταλύτη Pt/TiO2, αφού ο Pt αύξησε τη φωτοκαταλυτική ενεργότητα του υλικού και τη φωτοκαταλυτική απόδοση της αντίδρασης περισσότερο από τα υπόλοιπα μέταλλα. Οι βέλτιστες συνθήκες εναπόθεσης του Pt, ήταν η προσρόφησή του για 30 min από υδατικά διαλύματα Na2PtCl4 συγκέντρωσης 5*10-4 Μ και φωτοβόληση του υλικού για 15 min ώστε να πραγματοποιηθεί η αναγωγή. Η χρήση αυτού του φωτοκαταλύτη έδωσε σημαντικά αποτελέσματα φωτοκαταλυτικής αποικοδόμησης αλκοολών και άλλων προϊόντων βιομάζας σε υδατικά διαλύματα. Από τις ενώσεις που μελετήθηκαν, η χρήση της αιθανόλης και της γλυκερόλης οδήγησε στη μεγαλύτερη αύξηση του ρυθμού φωτοκαταλυτικής παραγωγής H2. Η αντίδραση της φωτοκαταλυτικής αναμόρφωσης πραγματοποιήθηκε κυρίως με χρήση υπεριώδους ακτινοβολίας UVA (Black light, ~360 nm), παρουσία ενώσεων με γενικό χημικό τύπο CxHyOz. Κυριότερες κατηγορίες αυτών των ενώσεων είναι οι αλκοόλες, τα σάκχαρα, οι πολυόλες και τα οργανικά οξέα. Επίσης, τα φωτοκαταλυτικά υμένια Pt/TiO2 είναι ικανά να προκαλέσουν την φωτοκαταλυτική παραγωγή H2 μέσα από μικρογαλακτώματα διασποράς ελαίου σε νερό. Η συνολική διεργασία της φωτοκαταλυτικής αναμόρφωσης αποτελεί μια ιδιαίτερα ελκυστική διεργασία, η οποία πραγματοποιείται με αρκετά ικανοποιητική απόδοση, με την κατάλληλη χρήση του φωτοκαταλύτη Pt/TiO2, σε μορφή λεπτών υμενίων. / Nanocrystalline titanium dioxide films, with deposited noble metals on their surface were studied for the photocatalytic production of Η2, through the so-called “photocatalytic reforming” processes. These films were deposited on glass substrates by using sol-gel procedures, carried out in the presence of acetic acid and a surfactant template, Triton X-100. The titania films consist of anatase nanocrystals, of about 12 nm average particle size. They were highly hydrophilic and were strong adsorbers of positively charged organic substances. Photodegradation of adsorbed dyes was very efficient on these titania nanoparticulate films. Photocatalytic hydrogen production was studied by using nanocrystalline films of Pt/TiO2. Pt gave the best results concerning photocatalytic activity of titanium dioxide. The best conditions of platinum deposition, through its adsorption from aqueous solutions, were 30 min of adsorption in the dark from an aqueous solution of Na2PtCl4, having a concentration of 5*10-4 M, followed by the reduction of the adsorbed ions of Pt (II) by UV treatment. Using this type of photocatalyst lead to high efficiency of photodegradation of alcohols and generally products, derived from biomass in aqueous solutions. From all the compounds examined, ethanol and glycerol gave the highest photocatalytic hydrogen production rates. The photocatalytic reforming reaction, was carried out using UVA (black light, ~360 nm) radiation, that comes from low-energy black light sources and was applied on chemical compounds that have the general chemical structure of CxHyOz. Several categories of substances may have this structure, such as alcohols, saccharides, polyols and organic acids. Also, photocatalytic nanocrystalline films Pt/TiO2 led to substantially efficient process of hydrogen production, by using colloidal dispersions of oil-in-water microemulsion. The whole process of photocatalytic reforming of several substances can be a very attractive and very promising process, by employing nanocrystalline titania films, Pt/TiO2.

Cement clinker production is a highly resource and energy intensive process and contributes substantially to annual global anthropogenic greenhouse gas emissions. One potential pathway to reduce the environmental footprint of cement-based materials is through the reduction of clinker content in concrete by partial replacement of cement with fillers. In this investigation, the partial replacement of cement with chemically inert nano and microsized fillers of titanium dioxide (TiO₂) and limestone was examined. The effects of nano and micro fillers on early-age properties, long-term properties, photocatalytic properties (for TiO₂-cement mixtures) and life cycle costs were measured and compared. Investigation of early-age properties shows that nanoparticles increase rate and degree of early cement hydration and chemical shrinkage due to heterogeneous nucleation effect. In contrast, coarser microparticles (>3µm in this research) maintain or marginally decrease the rate and degree of early cement hydration and decrease chemical shrinkage due to a dilution effect. In addition, temperature sensitivity of hydration reactions increases in the presence of nanoparticles. Investigation of long-term properties shows that pore size refinement is possible with the partial replacement of cement with nanoparticle fillers. But the long-term tests of filler-cement mixes also demonstrate that, compared to ordinary portland cement mix, the strength decreases and permeability increases. Analysis of photocatalytic properties of TiO₂-cement mixtures showed a lack of an appropriate testing procedure for nitrogen oxide (NOₓ) gas conversion by cement-based materials. Thus, a new standardized procedure and photocatalytic efficiency factor for characterizing photocatalytic NOₓ binding by cementitious materials is proposed. Life cycle analysis demonstrates that although inclusion of TiO₂ increases initial environmental impact of cementitious materials, the innovative photocatalytic properties of TiO₂ could improve sustainability. Life cycle analysis also shows that partial replacement of cement with limestone decreases environmental impact of cementitious mixtures due to lower processing “costs” of limestone compared to cement. Thus, the results from the current research demonstrate that variation of dosage and particle size of inert fillers can be used to tailor properties and structure of cement-based materials and that environmental sustainability can be improved by partial replacement of cement with inert fillers that introduce additional functionalities or fillers with lower embodied-energy and emissions.

In this thesis, the photochemical and photocatalytic degradation of atenolol (ATL) and 2-phenylbenzimidazole-5-sulfonic acid (PBSA) have been investigated in aqueous solutions. Our results show that direct photolysis of ATL is weak and the indirect photolysis, e.g., induced by photosensitizers such as nitrate, may contributed to its major loss process in natural sunlit waters. In the case of PBSA, direct photolysis is found to be important while the indirect photolysis may play a less important role in its elimination in natural surface waters. The photolytic reactions (either direct or indirect) generally obey pseudo-first-order kinetics and can be influence by the solution pH, the co-existence of other water constituents such as dissolved organic matter (DOM) and bicarbonate ion (HCO3-). The photolytic degradation lead to a variety of intermediates and products. However, the reduction in TOC of the photolysis is usually found to be insignificant compared to the disappearance of the mother compound. Nevertheless, the observed decrease in toxicity toward fresh water species D. magna in nitrate-induced photodegradation of ATL implies indirect photolysis of ATL is possibly an important way to reduce the toxicity to ecosystem. It should be noted that direct and indirect photodegradation may process through different pathways and mechanism as observed in the photolysis of PBSA in this work. Photocatalytic oxidation of ATL and PBSA were carried out in illuminated aqueous TiO2 suspensions. Photocatalytic reactions normally follow pseudo-first-order kinetics. The kinetics are strongly affected by the photocatalyst type, the photocatalyst dosage, the solution pH value and the substrate concentration. Hydroxyl radical (HO*) was determined to be the major reactive specie responsible for the remarkable degradation of mother compounds. The degradation efficiency is largely influenced by the water matrices as well as the formation and transformation of intermediates. It should be noted that Degussa P25 showed the highest photocatalytic activity for oxidizing ATL and PBSA compared to pure anatase or rutile catalyst such as Hombikat UV 100, Millennium PC 500 and Aldrich rutile, which is in line with previous reports. The photocatalytic degradation of mother compounds results in the formation of various intermediates (e.g., formic, oxalic, malonic acid) and inorganic ions (e.g., NH4+, NO3-, SO42-). TOC decreases much more slowly as compared to the disappearance of the mother compounds, however, complete mineralization could be obtained with longer irradiation time

Bacteria are the oldest, structurally simplest, and most abundant forms of life on earth. Its detection has always been a serious question since the emerging of modern science and technology. There has been a phenomenal growth in the field of real-time bacteria detection in recent years with emerging applications in a wide range of disciplines, including medical analysis, food, environment and many more. Two important analytical functions involved in bacteria detection are cell lysis and polymerase chain reaction (PCR). Cell lysis is required to break cells open to release DNA for use in PCR. PCR is required to reproduce millions of copies of the target genes to reach detection limit from a low DNA concentration. Conventionally, cell lysis and PCR are performed separately using specialized equipments. Those bulky machines consume much more than needed chemical reagents and are very time consuming. An efficient, cost-effective and portable solution involving Nanotechnology and Lab-on-a-Chip (LOC) technology was proposed. The idea was to utilize the excellent antibacterial property of surface-functionalized nanoparticles to perform cell lysis and then to perform PCR on the same LOC system without having to remove them from the solution for rapid detection of bacteria. Nanoparticles possess outstanding properties that are not seen in their bulk form due to their extremely small size. They were introduced to provide two novel methods for LOC cell lysis to overcome problems of current LOC cell lysis methods such as low efficiency, high cost and complicated fabrication process. The first method involved using poly(quaternary ammonium) functionalized gold and titanium dioxide nanoparticles which were demonstrated to be able to lyse E. coli completely in 10 minutes. The idea originated from the excellent antibacterial property of quaternary ammonium salts that people have been using for a long time. The second method involved using titanium dioxide nanoparticles and a miniaturized UV LED array. Titanium dioxide bears photocatalytic effect which generates highly reactive radicals to compromise cell membranes upon absorbing UV light in an aqueous environment. A considerable reduction of live E. coli was observed in 60 minutes. The thesis then evaluates the effect of nanoparticles on PCR to understand the roles nanoparticles play in PCR. It was found that gold and titanium dioxide nanoparticles induce PCR inhibition. How size of gold nanoparticles affected PCR was studied as well. Effective methods were discovered to suppress PCR inhibition caused by gold and titanium dioxide nanoparticles. The pioneering work paves a way for the integration of nanoparticle cell lysis and LOC PCR for rapid detection of bacteria. In the end, an integrated system involving nanoparticle cell lysis and microchip PCR was demonstrated. The prototyped system consisted of a physical microchip for both cell lysis and PCR, a temperature control system and necessary interface connections between the physical device and the temperature control system. The research explored solutions to improve PCR specificity in a microchip environment with gold nanoparticles in PCR. The system was capable of providing the same performance while reducing PCR cycling time by up to 50%. It was inexpensive and easy to be constructed without any complicated clean room fabrication processes. It can find enormous applications in water, food, environment and many more.

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

The use of a CO2 infrared (IR) laser and photocatalysis for water treatment microorganism disinfection purposes was investigated. During CO2 infrared (IR) laser treatment E. cloacae inactivation was comparable to inactivation via ultraviolet (UV) treatment; however no inactivation of the more resistant B. subtilis endospores occurred. Fourier Transform Infrared-Attenuated Total Reflectance (FTIR-ATR) spectroscopy of the bacterial cells displayed increased polysaccharide contents after IR treatment. FTIR and Raman spectroscopy of simple carbohydrates before and after IR laser treatment displayed no spectral changes, with the exception of N-acetyl-D-glucosamine (NAG), which was partially attributed to sampling techniques. E. cloacae inactivation during IR treatment was attributed to localised and overall temperature increases within the water. Due to the inability to inactivate B. subtilis endospores this technique is not suitable for water treatment purposes. Photocatalytic water treatment using novel TiO2 colloids prepared via a postsynthetic microwave-modification process (MW-treated) was also examined. These colloids were characterised using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analyses and compared to Degussa P25 and convection hydrothermally-treated (HT-treated) TiO2. Slurry suspensions displayed comparable E. coli inactivation rates, so the colloids were examined in immobilised form using both a model organic degradant, oxalic acid, and E. coli. Oxalic acid degradation studies showed that the MW-treated colloids displayed similar inactivation rates to the HT-treated TiO2, due to their pure anatase composition, while Degussa P25 displayed higher inactivation rates. Investigations into the effect of shortening UV wavelength were also performed. Degussa P25 was the only catalyst which displayed higher apparent quantum yields upon shortening the UV wavelength, which was attributed to its mixed-phase anatase-rutile composition. As E. coli inactivation was observed using distilled water, photocatalysis in natural river water was trailed. It was discovered that the pH had to be lowered from 7.5 to 5.0 and the initial cell concentration must be approximately 1 x 103 colony forming units (CFU) per cm3 or less for inactivation to be observed during a 5 hour treatment period. At a catalyst loading of 1.0 mg per cm2, Degussa P25 absorbed all the applied UVA irradiation; however the MW- and HT-treated TiO2 colloids did not due to their smaller particle size. Therefore sandwich experiments were devised to evaluate the effect of unabsorbed UV irradiation within the system. Small colony variants were identified after photocatalytic and UV treatment, which pose a potential threat to public health. Further investigation of the different TiO2 colloids was performed using in situ FTIR, both with and without an applied potential and compared to a thermally prepared TiO2 catalyst. The latter displayed potential dependent photocatalysis, while the mesoporous TiO2 catalysts displayed potential independent photocatalysis. All catalyst types displayed increased degradation rates upon the application of a positive bias, which was followed in situ via the production of CO2. Sodium oxalate and NAG was examined for photocatalytic degradation, both of which were degraded to CO2, with proposed break-down products identified when using NAG.

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

La dépollution de l'eau est un des enjeux majeurs du XXIème siècle. Si différentes techniques de retraitement existent déjà, nous investiguons une nouvelle méthode associant les propriétés des membranes filtrantes à celles des matériaux photocatalytiques. Ainsi, nous avons étudié la croissance et l'activité photocatalytique de structures de type noyau/coquille de ZnO/SnO2 intégrées dans des membranes méso-poreuses (alumine poreuse) et macro-poreuses (fibres de verre). L'activité photocatalytique de ces matériaux a été évaluée sur des polluants modèles tels que le bleu de méthylène ou l'acide salicylique, mais aussi sur des polluants organiques identifiés dans les eaux de la rivière luxembourgeoise Alzette. L'impact environnemental des matériaux développés a été déterminé grâce a des analyses de cytotoxicité sur des cellules colorectales de type Caco-2, ainsi que sur des bactéries marines de type Vibrio Fischeri. / Water treatment is one of the main challenge to overcome on the XXIst century. If many different techniques already exist, we investigate a new process associating the properties of porous membranes and photocatalytic materials. Thus, we studied the growth and photoactivity of core/shell structures of ZnO/SnO2 integrated into mesoporous (AAO) and macro-porous (glass fiber) membranes . The photocatalytic activity of these materials has been evaluated on organic pollutants like methylene blue or salicylic acid, but also on molecules found in the Luxembourgish Alzette river. The environmental impact of the synthesized structures has been determined with cytotoxic analyses on Caco-2 cells and Vibrio Fischeri bacteria.

Ce projet s’inscrit dans la contribution à l’élaboration de tenues de protection vis-à-vis d’agents chimiques de guerre : les combinaisons actuelles ont un rôle de barrière, qui stoppent le contaminant sans le dégrader, conduisant à un risque de contamination croisée accru. L’idée novatrice est de recouvrir ces textiles avec une couche intelligente multifonctionnelle et transparent associant un composé actif (TiO2, capable de photo-oxyder les composés toxiques sous irradiation à température ambiante) à un composé passif (nanostructures carbonées, permettant de stocker temporairement les produits de réaction ou le contaminant en cas de manque de lumière ou de pic de contamination). L’étude a commencé sur surfaces modèles afin d’optimiser l’association par assemblages par la méthode Layer-by-Layer (LbL) des différents éléments à savoir, TiO2 à un polymère (PDDA), à du graphène, à du charbon actif ou encore à des nanodiamants. L’efficacité photocatalytique de cette couche sur la dégradation d’un simulant gazeux du gaz moutarde a été testée. Les meilleures revêtements ont ensuite été transférés sur textile et leur efficacité évaluée sur un simulant liquide du gaz Sarin. Des études plus spécifiques ont également été menées pour comprendre l’influence des différents constituants et de l’épaisseur sur l’efficacité photocatalytique du film. Le renforcement de ces textiles fonctionnels contre des contraintes d’abrasion et de lavage a aussi été étudié, ainsi que sa régénération après tests photocatalytiques. / This project is focused on the elaboration of protective suits against Chemical Warfare Agents. Indeed, the suits currently used mainly act as physical barriers, without any degradation of the toxic molecules, thus increasing cross-contamination risks.The original idea is to functionalise textile fibers with a multifunctional, multicomponent and transparent smart layer, combining active components (TiO2, for photo-oxidation of toxic agents under irradiation at room temperature) to passive components (carbon nanostructures, in order to temporary stock the reaction products or the contaminant in case of lack of irradiation or of high contamination level). The study begins on model surfaces, in order to optimise Layer-by-Layer (LbL) association of TiO2 with polymer, graphene, activated carbon, or nanodiamonds. The photocatalytic efficiency of the layer was evaluated towards the degradation of a gaseous mustard gas simulant. The best functionalisations were then transferred to textile and their photocatalytic efficiency were evaluated towards the degradation of a liquid simulant of Sarin gaz. Some detailed results were obtained in order to understand the impact of the different components and of the thickness of the films on the activity. Textiles reinforcement against abrasion and washing were also studied, as well as their regeneration after photocatalytic tests.

La photocatalyse est un procédé d’oxydation avancée et son utilisation est répandue dans le traitement de l’eau. Cette thèse traite de la dépollution d’eau au sein d’un réacteur original mettant en oeuvre un textile lumineux photocatalytique. Le textile est composé de fibres optiques parallèles situées sur une face d’un tissu fibreux. L’unité d’un tel système est assurée par des points de liage répartis périodiquement fixant les fibres optiques au tissu. Un traitement de microtexturation des fibres optiques permet la création d’une multitude de trous sur leur surface latérale. Une émission de lumière macroscopiquement homogène est provoquée lors de la connexion des fibres optiques à une lampe UV. Un dépôt de catalyseur, tel que le dioxyde de titane, sur l’intégralité du textile, conjuguée au rayonnement UV induit une activité photocatalytique. Cette thèse consiste à l’étude des phénomènes agissant dans un dispositif intégrant le textile lumineux photocatalytique. Dans ce réacteur plan modèle, le textile est confiné entre deux plaques et un écoulement unidirectionnel parallèle aux fibres optiques est mis en oeuvre. La dépollution d’un fluide par photocatalyse résulte du couplage de plusieurs mécanismes : écoulement, transport et réaction. Des modèles numériques sont ainsi développéssur un volume élémentaire représentatif du textile (appelé RVE) pour simuler la dépollution d’une eau comportant une molécule test, à l’échelle microscopique. Cette géométrie est choisie en tenant compte des caractéristiques structurelles du textile photocatalytique. La première étape est l’analyse de l’hydrodynamique au sein du textile, qui couple des écoulements fluide et en milieu poreux. Une étude expérimentale préliminaire a permis l’acquisition de données nécessaires à une représentation réaliste de l’écoulement en milieu poreux. Dans un second temps, le transport est caractérisé par une étude de la distribution des temps de séjour (DTS) au sein du réacteur. Des simulations successives utilisant des conditions aux limites pseudo-périodiques sont réalisées pour calculer numériquement la DTS. Elles sont validées par des mesures expérimentales de traçage de colorant. Enfin, la dégradation d’une molécule test est analysée expérimentalement et numériquement. L’étude numérique présente des approches macroscopique et microscopique. L’étude à l’échelle macroscopique permet de quantifier globalement les performances du réacteur et de fournir des valeurs de constantes cinétiques nécessaires aux simulations àl’échelle microscopique. Une analyse fine et précise de la dépollution est ainsi réalisée au sein du RVE. Elle montre les atouts et limitations du réacteur modèle en termes d’efficacité de dépollution et d’homogénéité de fonctionnement. Des propositions d’améliorations sont finalement émises, notamment une configuration de réacteur comportant un empilement de textiles photocatalytiques. / The photocatalysis is known as an advanced oxidation process and its use is common for the water treatment. This thesis deals with the water depollution within an original reactor integrating the UV-light photocatalytic textile. The textile is composed of parallel optical fibres located on a side of a fibrous fabric. The unity of the system is ensured by bonding points periodically distributed fixing the optical fibres to the fabric. A microtexturization treatment is applied to the optical fibres and a multitude of punctual light sources are thus created on their lateral surface. A light emission macroscopically homogeneous is provided by the connection of optical fibres to an UV lamp. The coating of catalyst, such as titanium dioxide, associated with UV irradiation generates photocatalytic activity. This thesis consists in studying phenomena which occurs within a setup containing the UV-light photocatalytic textile. In this model plane reactor, the textile is confined between two plates and a unidirectional flow parallel to optical fibres is applied. The fluid depollution results of the coupling between several mechanisms : fluid flow, transport and reaction. Numerical models are thus developed on a representative volume element of the textile (called RVE) to simulate at the microscopic scale the depollution of water containing a test molecule. This geometry is designed by taking account the structural characteristics of the photocatalytic textile. The first stage is the analysis of the hydrodynamic within the textile that combines free flow regions and porous medium flows. A preliminary experimental study allows the acquisition of data necessary to a realistic representation of the porous medium flow. Secondly, the transport is characterized by a study of the residence time distribution (RTD) within the reactor. Successive simulations using pseudo-periodic boundary conditions are performed to numerically calculate the RTD. They are validated by experimental measurements using dye tracing. Finally, the degradation of a test molecule is analysed experimentally and numerically. The numerical study presents both approaches macroscopic and microscopic. The study at the macroscopic scale allows to globally quantify the reactor performances. On the other hand, kinetic constants necessary to simulations at the microscopic scale are determined by fitting of the macroscopic model with experimental measurements. An accurate analysis is thus realized within the RVE. It points the advantages and limitations of the model reactor in terms of depollution efficiency and functioning homogeneity. Suggestions of structural improvement are proposed and especially a reactor integrating a stack of photocatalytic textiles.