Aujourd'hui, l'impact environnemental de chaque technologie fait l'objet de toutes les attentions. L'élimination des composés soufrés et surtout de H2S dans les gaz entre dans cet aspect écologique au sein de plusieurs processus industriels. L'oxyde de zinc est utilisé comme adsorbant régénérable pour la désulfuration. Le but de ce travail est la préparation de filtres monolithiques macroporeux et de nanopoudres de ZnO avec une forte capacité en soufre et facilement régénérable, ainsi que l'optimisation de leurs propriétés.Des matériaux composites ZnS/NaCl sont tout d'abord synthétisés par combustion auto-propagée à partir de mélanges de zinc, de soufre et de chlorure de sodium. NaCl est éliminé par lixiviation dans l'eau après la synthèse. Les nanopoudres de ZnS sont préparées par mécanosynthèse à partir de mélanges de zinc et de soufre. Les deux matériaux préparés ont des structures cristallines différentes, de type würtzite pour les filtres de ZnS et de type sphalerite pour les poudres. Cette différence est due aux deux voies de synthèse. Monolithes et poudres ZnS sont ensuite convertis en ZnO par traitement thermique sous air à 700 °C.Les transformations macro- et microstructurales des filtres et des poudres ont été étudiées au cours de cycles de sulfuration-oxydation par les méthodes de caractérisation telles que la diffraction des rayons X, la microscopie électronique à balayage et la porosimétrie au mercure. Les résultats montrent que les propriétés des matériaux restent très stables au cours des conversions successives. Enfin, les filtres et nanopoudres de ZnO ont été utilisés comme adsorbants au cours d'essais de désulfuration. La capacité massique en soufre des filtres est assez faible, 6,4 mg S/g ads. montrant que la porosité doit être améliorée. Quant aux nanopoudres, la capacité massique en soufre est très élevée, 272 mg S/g ads, prouvant que la surface spécifique est très importante pour ce type d'application. / Today, we have to take care of every technology's environmental effects. The removal of H2S and other sulfur compounds in hot gas enters this ecological aspect in several industrial processes. Zinc oxide is used here as a regenerable sorbent for gas desulfurization. The goal of this work is, the preparation of macroporous ZnO monolithic filters and nanopowders with high sulfur capacity and easily regenerable, and their optimization with the control of their properties. ZnS/NaCl composite materials are first obtained by Self-propagating High temperature Synthesis from mixtures of zinc, sulfur and sodium chloride powders. NaCl is then removed by lixiviation with water. ZnS nanopowders are prepared by mechanical alloying from mixtures of zinc and sulfur. The two materials have different crystalline structure, würtzite type for ZnS filters and sphalerite type for powders, because of the way of synthesis. Then, they are converted into ZnO by thermal treatment under air at 700 °C. Next, the macro- and microstructure transformations of both filter and powders during sulfidation-oxidation cycles are thus considered. Results of all characterizations like X-ray diffraction, scanning electron microscopy and Hg porosimetry show that materials properties are very stable against conversions. Afterwards, ZnO filters and nanopowders are used as adsorbent in desulfurization trials. The sulfur capacity of filters is not so high, 6,4 mg S/g ads and shows that porosity has to be improved. Regarding nanopowders, the sulfur capacity is very high, 272 mg S/g ads, proving that surface area is very important in this application.

Nesse trabalho de duas partes, colunas monolíticas poliméricas foram aplicadas em extração em fase sólida e em nanocromatografia capilar, duas das suas mais importantes aplicações. Na primeira parte foi desenvolvido um monolito para extração em fase sólida dos metais Cd(II), Pb(II) e Cu(II), que foi acoplada on-line com detecção eletroquímica com o auxílio de instrumentação de análise por injeção sequencial (SIA). A coluna usada como suporte sólido para extração em fase sólida foi obtida com a copolimerização entre formador de ligação cruzada etileno dimetacrilato (EDMA) e monômero funcional glicidil metacrilato (GMA), preparada a partir de uma mistura reacional composta de 30% GMA, 10% EDMA, 5% H2O, 35% n-propanol e 20% 1,4- butanodiol, aquecida durante 24 horas à 60°C. Essa composição e condições de polimerização favoreceram a permeabilidade do monolito, o que foi necessário para o acoplamento no SIA. Após a obtenção do monolito base o mesmo foi modificado pela reação do anel epóxi do grupo GMA com ácido iminodiacético (IDA) para garantir propriedades de quelação de metais e maior capacidade de adsorção para a coluna. O monolito foi caracterizado com imagens de microscopia de varredura eletrônica (MEV) e a capacidade de extração foi de 4,4 ± 0,3 mg Cu(II) m-1 obtida com curvas de breakthrough. O método de determinação on-line dos metais operado por SIA, que executou as etapas de carregamento de amostra, limpeza da coluna, eluição dos analitos e recondicionamento dos sítios ativos teve frequência amostral de 6,8 injeções por hora. Os limites de detecção (LD) e quantificação (LQ) para o método foram, respectivamente, de 1,0 e 3,3 µg L-1 para o Cd(II), 0,7 e 2,2 µg L-1 para o Pb(II) e 0,5 e 1,8 µg L-1 para o Cu(II). O método foi aplicado na determinação dos metais em diferentes matrizes de águas naturais, sendo encontrado Cu(II) em algumas amostras. A exatidão do método foi avaliada com estudos de adição e recuperação nessas águas, obtendo-se valores entre 75,5 e 116,6%. Na segunda parte do trabalho foi utilizada uma coluna polar composta da sulfobetaína zwitteriônica N,N-dimetil-N-metacriloil-oxietil-N-(3-sulfopropil) amônio betaína (MEDSA) e do formador de ligações cruzadas dioxietil dimetacrilato (DiEDMA) em Nanocromatografia de Interação Hidrofílica (HILIC) para fazer a separação de Dopamina, Epinefrina, Norepinefrina, L-DOPA, Tiramina, DOPAC e Ácido Homovanílico, neurotransmissores, alguns de seus metabólitos e precursores, compostos polares de baixa massa molecular. A seletividade cromatográfica da coluna foi altamente dependente da composição da fase móvel aquosa:orgânica, apresentando um mínimo de retenção na transição do mecanismo HILIC para a fase reversa (RP). Ajustando os dados experimentais de fatores de retenção em função da composição da fase móvel com o modelo de retenção duplo foi possível prever qual composição de fase móvel promoveria a separação dos analitos da mistura, que foi atingida em torno de 85% acetonitrila e 15% H2O. A coluna foi modificada com o grupo zwitteriônico 2-metacriloil-oxietil fosforilcolina (MPC) por UV grafting e a modificação da metade do comprimento da coluna durante 30 minutos de exposição UV levou às mudanças na seletividade cromatográfica. / In this two parts work, polymeric monolithic columns were applied in solid phase extraction and in capillary nanochromatography, two of their most important applications. In the first part, a monolith for solid phase extraction of Cd(II), Pb(II) and Cu(II) metals was developed and coupled online with electrochemical detection with the aid of sequential injection analysis instrumentation (SIA). The column used as a solid support for solid phase extraction was obtained by copolymerization between the crosslinker ethylene dimethacrylate (EDMA) and the functional monomer glycidyl methacrylate (GMA), prepared from a reaction mixture composed of 30% GMA, 10% EDMA, 5% H2O, 35% n-propanol and 20% 1,4-butanediol, heated at 60 ° C for 24 hours. This composition and polymerization conditions favored monoliths permeability, which was required for the SIA coupling. After obtaining the base monolith, it was modified by reaction of the epoxy ring of the GMA group with the iminodiacetic acid (IDA) to guarantee metals chelating properties and increase adsorption capacity for the column. The monolith was characterized by scanning electron microscopy (SEM) images and extraction capacity was 4.4 ± 0.3 mg Cu(II) m-1, obtained from breakthrough curves. The method for online determination of metals operated by SIA, which performed the steps of sample loading, column cleaning, analyte elution and reconditioning of active sites had a sampling throughput of 6.8 injections per hour. The limits of detection (LD) and quantification (LQ) for the method were, respectively, 1.0 and 3.3 µg L-1 for Cd(II), 0.7 and 2.2 µg L-1 for the Pb(II) and 0.5 and 1.8 µg L-1 for Cu(II). The method was applied for the determination of metals in different natural water matrices, finding Cu(II) in some samples. The accuracy of the method was evaluated with addition and recovery studies in these waters, finding recoveries between 75.5 and 116.6%. In the second part of the work, a polar column composed of the zwitterionic sulfobetaine N,N-dimethyl-N-methacryloyloxyethyl-N-(3-sulfopropyl) ammonium betaine (MEDSA) and the cross-linker dioxyethyl dimethacrylate (DiEDMA) was used in Hydrophilic Interaction Nanocromatography (HILIC) to separate Dopamine, Epinephrine, Norepinephrine, L-DOPA, Tyramine, DOPAC and Homovanilic Acid, neurotransmitters, some of its metabolites and precursors, which are polar compounds of low molecular mass. The chromatographic selectivity of the column was highly dependent on the composition of the aqueous:organic mobile phase, showing a minimum retention at the transition from the HILIC to the reverse phase (RP) mechanism. By adjusting the experimental data of retention factors as a function of mobile phase composition with the double retention model it was possible to predict which mobile phase composition would promote the separation of the mixed analytes, which was achieved around 85% acetonitrile and 15% H2O. The column was modified with the 2-methacryloyl oxyethyl phosphorylcholine (MPC) zwitterionic group by UV grafting and the modification of half columns length during 30 minutes of UV exposure led to changes in the chromatographic selectivity.

Nesse trabalho de duas partes, colunas monolíticas poliméricas foram aplicadas em extração em fase sólida e em nanocromatografia capilar, duas das suas mais importantes aplicações. Na primeira parte foi desenvolvido um monolito para extração em fase sólida dos metais Cd(II), Pb(II) e Cu(II), que foi acoplada on-line com detecção eletroquímica com o auxílio de instrumentação de análise por injeção sequencial (SIA). A coluna usada como suporte sólido para extração em fase sólida foi obtida com a copolimerização entre formador de ligação cruzada etileno dimetacrilato (EDMA) e monômero funcional glicidil metacrilato (GMA), preparada a partir de uma mistura reacional composta de 30% GMA, 10% EDMA, 5% H2O, 35% n-propanol e 20% 1,4- butanodiol, aquecida durante 24 horas à 60°C. Essa composição e condições de polimerização favoreceram a permeabilidade do monolito, o que foi necessário para o acoplamento no SIA. Após a obtenção do monolito base o mesmo foi modificado pela reação do anel epóxi do grupo GMA com ácido iminodiacético (IDA) para garantir propriedades de quelação de metais e maior capacidade de adsorção para a coluna. O monolito foi caracterizado com imagens de microscopia de varredura eletrônica (MEV) e a capacidade de extração foi de 4,4 ± 0,3 mg Cu(II) m-1 obtida com curvas de breakthrough. O método de determinação on-line dos metais operado por SIA, que executou as etapas de carregamento de amostra, limpeza da coluna, eluição dos analitos e recondicionamento dos sítios ativos teve frequência amostral de 6,8 injeções por hora. Os limites de detecção (LD) e quantificação (LQ) para o método foram, respectivamente, de 1,0 e 3,3 µg L-1 para o Cd(II), 0,7 e 2,2 µg L-1 para o Pb(II) e 0,5 e 1,8 µg L-1 para o Cu(II). O método foi aplicado na determinação dos metais em diferentes matrizes de águas naturais, sendo encontrado Cu(II) em algumas amostras. A exatidão do método foi avaliada com estudos de adição e recuperação nessas águas, obtendo-se valores entre 75,5 e 116,6%. Na segunda parte do trabalho foi utilizada uma coluna polar composta da sulfobetaína zwitteriônica N,N-dimetil-N-metacriloil-oxietil-N-(3-sulfopropil) amônio betaína (MEDSA) e do formador de ligações cruzadas dioxietil dimetacrilato (DiEDMA) em Nanocromatografia de Interação Hidrofílica (HILIC) para fazer a separação de Dopamina, Epinefrina, Norepinefrina, L-DOPA, Tiramina, DOPAC e Ácido Homovanílico, neurotransmissores, alguns de seus metabólitos e precursores, compostos polares de baixa massa molecular. A seletividade cromatográfica da coluna foi altamente dependente da composição da fase móvel aquosa:orgânica, apresentando um mínimo de retenção na transição do mecanismo HILIC para a fase reversa (RP). Ajustando os dados experimentais de fatores de retenção em função da composição da fase móvel com o modelo de retenção duplo foi possível prever qual composição de fase móvel promoveria a separação dos analitos da mistura, que foi atingida em torno de 85% acetonitrila e 15% H2O. A coluna foi modificada com o grupo zwitteriônico 2-metacriloil-oxietil fosforilcolina (MPC) por UV grafting e a modificação da metade do comprimento da coluna durante 30 minutos de exposição UV levou às mudanças na seletividade cromatográfica. / In this two parts work, polymeric monolithic columns were applied in solid phase extraction and in capillary nanochromatography, two of their most important applications. In the first part, a monolith for solid phase extraction of Cd(II), Pb(II) and Cu(II) metals was developed and coupled online with electrochemical detection with the aid of sequential injection analysis instrumentation (SIA). The column used as a solid support for solid phase extraction was obtained by copolymerization between the crosslinker ethylene dimethacrylate (EDMA) and the functional monomer glycidyl methacrylate (GMA), prepared from a reaction mixture composed of 30% GMA, 10% EDMA, 5% H2O, 35% n-propanol and 20% 1,4-butanediol, heated at 60 ° C for 24 hours. This composition and polymerization conditions favored monoliths permeability, which was required for the SIA coupling. After obtaining the base monolith, it was modified by reaction of the epoxy ring of the GMA group with the iminodiacetic acid (IDA) to guarantee metals chelating properties and increase adsorption capacity for the column. The monolith was characterized by scanning electron microscopy (SEM) images and extraction capacity was 4.4 ± 0.3 mg Cu(II) m-1, obtained from breakthrough curves. The method for online determination of metals operated by SIA, which performed the steps of sample loading, column cleaning, analyte elution and reconditioning of active sites had a sampling throughput of 6.8 injections per hour. The limits of detection (LD) and quantification (LQ) for the method were, respectively, 1.0 and 3.3 µg L-1 for Cd(II), 0.7 and 2.2 µg L-1 for the Pb(II) and 0.5 and 1.8 µg L-1 for Cu(II). The method was applied for the determination of metals in different natural water matrices, finding Cu(II) in some samples. The accuracy of the method was evaluated with addition and recovery studies in these waters, finding recoveries between 75.5 and 116.6%. In the second part of the work, a polar column composed of the zwitterionic sulfobetaine N,N-dimethyl-N-methacryloyloxyethyl-N-(3-sulfopropyl) ammonium betaine (MEDSA) and the cross-linker dioxyethyl dimethacrylate (DiEDMA) was used in Hydrophilic Interaction Nanocromatography (HILIC) to separate Dopamine, Epinephrine, Norepinephrine, L-DOPA, Tyramine, DOPAC and Homovanilic Acid, neurotransmitters, some of its metabolites and precursors, which are polar compounds of low molecular mass. The chromatographic selectivity of the column was highly dependent on the composition of the aqueous:organic mobile phase, showing a minimum retention at the transition from the HILIC to the reverse phase (RP) mechanism. By adjusting the experimental data of retention factors as a function of mobile phase composition with the double retention model it was possible to predict which mobile phase composition would promote the separation of the mixed analytes, which was achieved around 85% acetonitrile and 15% H2O. The column was modified with the 2-methacryloyl oxyethyl phosphorylcholine (MPC) zwitterionic group by UV grafting and the modification of half columns length during 30 minutes of UV exposure led to changes in the chromatographic selectivity.

Dans le contexte actuel de développement de nouvelles sources d'énergie non fossiles tout en minimisant l'impact environnemental, la production de carburants solaires par la valorisation des émissions anthropiques de CO2 apparaît comme une solution à fort potentiel. Le principal défi dans les processus artificiels photo-induits concerne le caractère bidimensionnel des systèmes utilisés, en raison de la faible profondeur de pénétration des photons. Ce travail de thèse se concentre sur le développement de mousses solides alvéolaires, issues de la chimie intégrative, présentant une porosité hiérarchiquement organisée. A travers l’imprégnation de précurseurs de TiO2, des photocatalyseurs autosupportés ont été synthétisés et ont montré une augmentation de la pénétration des photons d’un ordre de grandeur. D’autre part, ces solides limitent les réactions inverses par un effet de dilution, tout en assurant une sélectivité élevée envers la génération d'alcanes. Un modèle cinétique, basé sur un formalisme mixte de Langmuir-Hinshelwood et Eley-Rideal, est proposé pour décrire le comportement des matériaux. / In the current context of developing novel non-fossil energy sources while minimizing the environmental impact, solar-driven-fuel-production by exploiting anthropogenic CO2 emissions appears to be a solution with great potential. The main challenge in artificial photo-induced processes concerns the two-dimensional character of the systems used, due to the low photon penetration depth. This thesis work focuses on the development of alveolar solid foams, derived from integrative chemistry and bearing a hierarchically organized porosity. By TiO2 precursor impregnation, self-standing photocatalysts were synthesized and provided a photon penetration increase by an order of magnitude. Moreover, these solids limit back-reactions by a dilution effect, while ensuring high selectivity towards alkane generations. A kinetic model, based on a mixed formalism of Langmuir-Hinshelwood and Eley-Rideal, is proposed to describe material behavior.

La conversion du dioxyde de carbone en molécules d'intérêts est un enjeu majeur de notre société moderne. Actuellement, ces réactions sont très coûteuses en énergie, impliquent de hautes pressions et températures et sont faiblement sélectives. Une alternative séduisante serait l’utilisation d’enzymes redox, i.e. des déshydrogénases, qui fonctionnent à pH neutre, température et pression ambiantes et sont très sélectives. Le frein à leur utilisation est leur stabilité et le fait qu’elles nécessitent la présence du cofacteur nicotinamide adénine dinucléotide (NAD+ / NADH), couteux et délicat à régénérer. L’immobilisation de déshydrogénases sur des supports poreux monolithiques est proposée dans ce travail de thèse dans l’objectif de développer des réacteurs en flux continu.Dans un premier temps, des monolithes siliciques à porosité hiérarchique macro- et mésoporeux ont été préparés. Des macropores plus larges allant jusqu’à 35-50 microns ont été obtenus. Dans un second temps, des synthèses de monolithes de carbone à porosité hiérarchique en une étape ou en plusieurs étapes par dépôt de carbone sur des monolithes siliciques (greffage de saccharose, suivi de polymérisation et carbonisation) ont été développées. Ce travail a permis un contrôle fin de la macro-, méso et microporosité. Des monolithes de carbone avec une surface spécifique supérieure à 1200 m2.g-1 ont notamment pu être obtenus. Ces matériaux présentent non seulement une macroporosité large (35-50 µm), mais également une mésoporosité bimodale. Au-delà d’une porosité multi-échelle, ces matériaux carbonés présentent l’avantage d’être conducteurs du courant électrique. Ils peuvent ainsi être utilisés comme support pour l’électrocatalyse enzymatique. Ces monolithes de carbones ont été utilisés pour l’immobilisation de formiates déshydrogénases connus pour pouvoir réduire le CO2 en présence du cofacteur NADH. La régénération du cofacteur est étudiée soit par voie électrochimique soit par voie biocatalytique à l'aide d'une deuxième enzyme la phosphite déshydrogénase. Des études de fonctionnalisation des monolithes carbonés pour la co-immobilisation des enzymes et du cofacteur ont également été initiées. / Carbon dioxide (CO2) is a greenhouse gas that results, in part, from human activities and causes global warming and climate change. According to the International Energy Agency, global CO2 emissions from fossil-fuel combustion reached a record high of 31.3 gigatonnes in 2011. The concept of the methanol economy, advocated by Nobel laureate Prof. George A. Olah back in the 1990s, hinges on the chemical recycling of CO2 to methanol and derived, suggesting methanol as a key substitute fuel and starting material for valuable chemicals. The recycling conversion of CO2 could be a rational way to develop an anthropogenic short-term carbon cycle. With this aim, The design of functional porous architectures depicting hierarchical and interconnected pore networks has emerged as a challenging field of research. Particularly, porous monoliths offer many advantages and can be employed as flow-through reactors for separation, catalysis and biocatalysis. This study focuses on the design of monoliths with hierarchical porosity and high surface area. Firstly, silica monoliths with both homogeneous macro- and mesopores were prepared using sol-gel chemistry and spinodal decomposition using PEO polymers. Macropore (up to 30 microns) and mesopore (up to 20 nm) diameters of the monoliths were controlled by modifying various experimental parameters (PEO molecular weight, addition of surfactants, different basic post-treatments, different temperatures, etc.). Secondly, carbonaceous replica have been prepared through hydrothermal carbonization of sucrose, subsequent pyrolysis and silica etching. These materials present large interconnected flow-trough macropores, a bimodal mesoporosity, a high surface area (up to 1400 m2 g-1) and high meso- and macropore volumes.Different enzymes were immobilized onto the monoliths amongst which formate dehydrogenases. Flow-through reactors were engineered and continuous flow biocatalysis was performed. In such systems, straightforward processes for the in situ regeneration of the enzyme cofactor, i.e. 1,4-NADH wrer developped. Flow-through reactors and their use for the enzymatic reduction of carbon dioxide into formate were designed.