Le présent travail porte sur la photodégradation de polluants aqueux utilisant des catalyseurs à base de ZnO. La première étape a consisté à fonctionnaliser ZnO avec des nanoparticules d'argent. Deux méthodes ont été utilisées : la photodéposition et l'imprégnation des particules d'argent sur ZnO. L’activité des catalyseurs obtenus vis-à-vis de la dégradation du bisphenol-A, du triclosan et de la rhodamine-B a été ensuite étudiée. L'effet du pH, des concentrations du photocatalyseur et du polluant et de la longueur d'onde sur la dégradation du bisphenol-A a été analysée et la constante cinétique déterminée. L'optimisation a montré qu'une teneur faible en argent et un pH alcalin, tant pour la fonctionnalisation de ZnO que pour la photodégradation, maximisent la constante cinétique de dégradation du bisphenol-A. Un modèle a également prédit que le système obtenu par photodéposition présente une activité photocatalytique supérieure à celle de celui obtenu par imprégnation. D'autre part, pour surmonter des problèmes d'agrégation, les particules d’Ag/ZnO ont été immobilisées grâce à leur incorporation dans une matrice d'acide polyacrylique réticulé. La surface des particules de catalyseur a, au préalable, été modifiée grâce à un agent de couplage silané qui a permis (i) la dispersion et l'ancrage par estérification des nanoparticules sur la matrice polyacrylique (ii) de promouvoir la cristallisation du polymère. Les composites obtenus ont été testés avec succès sous rayonnement UV avec une efficacité comparable à celle des particules non-immobilisées. L'immobilisation permet par ailleurs d'empêcher la photocorrosion du catalyseur et d'utiliser ces composites en mode continu / The present work concerns photodegradation of water contaminants using ZnO-based catalysts. The first step consisted in designing a new catalytic system by functionalizing ZnO with silver nanoparticles. Two methods were used: photodeposition and impregnation of silver nanoparticles (AgNPs) on ZnO. The photocatalytic activity of the resulting catalyst towards the degradation of bisphenol-A, triclosan and rhodamine-B was studied. The effect of pH, photocatalyst and contaminant concentrations and wavelength, on bisphenol-A degradation was studied and the kinetic rate constant was determined. The optimization showed that a low silver content and an alkaline pH, during both functionalization of ZnO and photodegradation, maximized the kinetic rate constant of bisphenol-A degradation. A model also predicted that Ag/ZnO obtained by photodeposition showed higher photocatalytic activity that of Ag/ZnO obtained by impregnation.On the other hand, to overcome aggregation problems, Ag/ZnO were immobilized owing to their incorporation in a cross-linked poly(acrylic acid) matrix . The surface of Ag/ZnO was previously modified, using a silane coupling agentwhich allowed (i) dispersing and anchoring NPs on the polyacrylic matrix by formation ester bonds (ii) promoting crystallization of the polymer. The composites were successfully tested under UV light with an efficiency comparable to that of non-immobilized NPs. The immobilization provides additional advantages e.g. hindrance of catalyst photocorrosion and possible use of the composite in continuous mode

L’objectif principal de ce travail a été d’étudier le potentiel de mousses alvéolaires tridimensionnelles en carbure de silicium de forme béta (β-SiC) comme support de photocatalyseur, dans le but de mettre au point des réacteurs photocatalytiques structurés pour le traitement de l’air. Ces mousses alvéolaires de β-SiC de surface spécifique moyenne et de porosité très ouverte sont obtenues par la synthèse dite à mémoire de forme (Shape Memory Synthesis), consistant en la carburation contrôlée d’une mousse alvéolaire de polyuréthane préformée. Une étude de la dégradation de trois polluants sur des films minces en mode de lit léchant (la méthyléthylcétone, l’ammoniac et le sulfure d’hydrogène) a tout d’abord permis de sélectionner trois photocatalyseurs d’intérêt parmi six références commerciales avant d’être immobilisés sur les mousses de β-SiC. Après une étape d’optimisation en termes de taille d’alvéoles, de nature et quantité de photocatalyseur, le média photocatalytique TiO2/mousses de β-SiC a été caractérisé et ses performances comparées en mode mono-passage ainsi qu’en mode de recirculation du flux dans une enceinte de 2 m3, à celles d’un film mince de TiO2 et d’un média photocatalytique commercial de référence. Le média photocatalytique TiO2/mousses de β-SiC présente des performances nettement améliorées par rapport à celles du média référent. Les mousses jouent un rôle de mélangeur statique et permettent une meilleure utilisation du volume du réacteur, en augmentation la densité de photocatalyseur par unité de volume tout en maintenant une illumination du cœur du réacteur acceptable ainsi que des pertes de charge très limitées. / The main objective of this work was to study the potential of three-dimension beta silicon carbide (β-SiC) alveolar foams for use as photocatalyst support, targeting the implementation of structured photocatalytic reactors for air treatment. Medium surface area β-SiC alveolar foams were synthesized according to the Shape Memory Synthesis concept, consisting in the controlled carburization of a preshaped polyurethane foam. First, the degradation of three model pollutants (methylethylketone, ammonia and hydrogen sulfide) was performed over TiO2 thin layers in a flow-through reactor for selecting three photocatalysts of interest – Hombikat UV100, PC500 and P25 TiO2 – among six commercial standards. The powderly photocatalysts were further immobilized onto β-SiC foams. After an optimization step in terms of mean cell size, light transmission, photocatalyst nature and weight content as well as of the immobilization method, the TiO2/β-SiC foam photocatalytic media was characterized and its photocatalytic behaviour was compared in a single-pass mode as well as in a recirulation mode inside a 2 m3 chamber, to those obtained on a TiO2 thin layer and with a well-known commercial photocatalytic felt media made from quartz fibers supporting sol-gel TiO2. The photocatalytic media elaborated with β-SiC alveolar foams exhibited superior performances compared to that of the commercial felt standard. The foams acted as static mixing within the reactor and allowed a more efficient use of the reactor volume, by increasing the photocatalyst density per reactor volume unit, while maintaining however a suitable illumination within the reactor core as well as very low pressure drops.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第17911号 / エネ博第283号 / 新制||エネ||59(附属図書館) / 30731 / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 佐川 尚, 教授 八尾 健, 教授 石原 慶一 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19740号 / 工博第4195号 / 新制||工||1647(附属図書館) / 32776 / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 庸裕, 教授 阿部 竜, 教授 陰山 洋 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21118号 / 工博第4482号 / 新制||工||1696(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 阿部 竜, 教授 安部 武志, 教授 作花 哲夫 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第21178号 / 人博第850号 / 新制||人||203(附属図書館) / 29||人博||850(吉田南総合図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 吉田 寿雄, 教授 内本 喜晴, 教授 田部 勢津久 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21789号 / 工博第4606号 / 新制||工||1717(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 庸裕, 教授 佐藤 啓文, 教授 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

In this doctoral thesis, we have studied the oxidation of carboxylic acids to obtain the corresponding acyloxy radicals, using visible light and non-toxic and inexpensive organic dyes, as photocatalysts. On the one hand, we study the photooxidation of aromatic carboxylic acids to obtain acyloxy radicals, whose decarboxylation is relatively slow (Chapter I and Chapter II). On the other hand, we describe the photooxidation of aliphatic carboxylic acids, to take advantage of the rapid decarboxylation of the corresponding acyloxy radicals, to generate nucleophilic radicals that were trapped by different reagents (Chapter III to Chapter V). It should be noted that all the protocols are free of expensive and toxic noble metals, the reactions were promoted with visible light at room temperature and the scalability of some reactions was demonstrated in batch conditions or using flow chemistry. In addition, mechanistic studies were carried out to propose plausible photocatalytic routes to all the reactions studied.

No description available.

The aim of my Ph.D. thesis is to summarize my research on the development of ring-opening polymerization (ROP) of O-carboxyanhydrides (OCAs) to synthesize functionalized, degradable polyesters. Biodegradable polyesters are promising alternatives to conventional petroleum-based non-degradable polyolefins and they are widely used in everyday applications ranging from clothing and packaging to agriculture and biomedicine. Commercially available polyesters, such as poly(lactic-co-glycolic acid), poly(lactic acid), and polycaprolactone, hydrolyze in physicochemical media. They have been approved by FDA and widely used for medical applications. However, the lack of side-chain functionality in polyesters and in corresponding monomers greatly plagues their utility for applications that demand physicochemical properties such as high stiffness, tensile strength and elasticity. Increasing efforts have been devoted to the introduction of pendant groups along the polymer chain in order to modify and modulate the physicochemical properties of polyesters and thereby to expand their applications. Over the last decade, OCAs have emerged as an alternative class of highly active monomers for polyester polymerization. OCAs are prepared from amino acids and thus have a richer range of side chain functionalities than lactone or lactide. Like lactones, OCAs can undergo ROP to obtain polyesters. Unfortunately, current ROP methods, especially those involving organocatalysts, result in uncontrolled polymerization including epimerization for OCAs bearing electron-withdrawing groups, unpredictable molecular weights (MWs), or slow polymerization kinetics. Based on our recent success of Ni/Ir photoredox catalysis allowing for rapid synthesis of high-MWs polyesters, we further explore new polymerization chemistry to use earth-abundant metal complexes to replace expensive rare-earth metal photocatalysts, and practice the polymerization in moderate and energy-efficient reaction conditions. This thesis introduces novel photoredox and electrochemical earth-abundant metal catalysts that overcome above difficulties in the ROP chemistry of OCAs, and allow for the preparation of stereoregular polyesters bearing abundant side-chain functionalities in a highly controlled manner. Specifically, various highly active metal complexes have been developed for stereoselective ROP of OCAs, either using light or electricity, to synthesize syndiotactic or stereoblock copolymers with different thermal properties. Additionally, simple purification protocols of OCAs have also been initially studied, which potentially paves the way to bulk production of functional monomers. In this thesis, I first describe newly-developed photoredox Co/Zn catalysts to achieve a controlled ROP of enantiopure OCAs under mild reaction conditions (Chapter 2). Such discovery is extended to the combination use of Co catalysts with various Zn/Hf complexes that enable stereoselective controlled ROP of racemic OCAs for the preparation of stereoregular polyesters (Chapter 3). The mechanistic studies of the aforementioned developments lead to the application of such a catalytic system in controlled electrochemical ROP of OCAs (Chapter 4). Such chemistry can also be translated to stereoselectively electrochemical ROP of racemic OCAs to either syndiotactic or stereoblock polyesters, allowing precise control of polyester's tacticity and sequence (Chapter 5). An overview future work has been summarized (Chapter 6). / Doctor of Philosophy / Polyesters are widely used in everyday applications ranging from clothing and packaging to agriculture and biomedicine. Different from conventional unrecyclable plastics, polyesters are usually biocompatible and biodegradable, and can be synthesized from renewable resources. A few commercially available polyesters have been approved by FDA and widely used for medical applications. However, their utility for applications that demand various mechanical and chemical properties is greatly limited by the lack of side-chain functional groups in polyesters and in their monomers—lactones. Increasing efforts have been devoted to the introduction of pendant groups along the polymer chain in order to modify and modulate the desired properties of polyesters and thereby to expand their applications. Over the last decade, O-carboxyanhydrides (OCAs) have emerged as an alternative class of highly active monomers for polyester polymerization. OCAs can be prepared from renewable source amino acids and thus have a richer range of side chain functional groups. Like lactones, OCAs can undergo ring-opening polymerization (ROP). Unfortunately, current ROP methods usually result in uncontrolled polymerization of OCAs including loss of stereoregularity, unpredictable molecular weights, or slow polymerization rate. To address the above-described polymer chemistry and materials challenges, I have been motivated to develop a new polymer chemistry knowledge base when starting my Ph.D. program. I was first involved in the development of a controlled photoredox polymerization of OCAs produces polyesters with various side chain functional groups. By using photoredox Ni/Zn/Ir catalysts, stereoregular high molecular weight polyesters can be synthesized from racemic OCAs in a rapid, controlled manner. However, this catalytic system has to be used at -20 °C despite so successful in preparing stereoblock polyesters. Encouraged by our recent success in this area, I started to work on the discovery of other transition metal complexes such as the Co complexes used in N-carboxyanhydride polymerization. Ultimately, innovative photoredox Co/Zn catalysts has been successfully developed, and applied to our protocol to achieve the controlled ROP of enantiopure OCAs under mild reaction condition (Chapter 2). The Co catalyst can replace both Ni and Ir in aforementioned photoredox system. Meanwhile, the combination of Co catalysts and various Zn/Hf complexes has also been developed to undergo photoredox ROP of racemic OCAs to efficiently produce polyesters with different microstructures (Chapter 3). Although photoredox ROP is an efficient method for synthesizing degradable polyesters, great decrease in photonic flux with the depth of the reaction medium makes it less energy efficient compared to electricity. Therefore, we then extended our protocol to electrochemical reaction, which is one of the most energy-efficient chemical reactions. The newly identified Co/Zn catalytic system can be activated by electric current to mediate rapid electrochemical ROP (eROP) of enantiopure OCAs, allowing for the synthesis of isotactic polyesters in a highly controlled manner (Chapter 4). Additionally, stereoselective eROP of racemic OCAs has been firstly achieved by using various combinations of Co and Zn/Hf complexes (Chapter 5). In summary, my research produces unique and transformative insights into the innovative photoredox and electrochemical ROP mediated by metal catalysts. Given the importance and versatility of biodegradable and biocompatible polyester materials, the chemistry invented by our team can be expected to serve as a new platform for various applications in material and biomedical engineering.