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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Développement d'électrodes modifiées et d'un bioréacteur électrochimique à flux continu pour une application aux biopiles microbiennes / Development of modified electrodes and a continuous flow electrochemical bioreactor for microbial fuel cells applications

Champavert, Joffrey 18 July 2016 (has links)
Les biopiles microbiennes sont des sources d’énergies renouvelables utilisant des bactéries qui convertissent une énergie chimique en électricité. Pour cela, l’anode doit collecter les électrons issus des microorganismes. La sélection d’un matériau d’anode possédant de grandes performances est d’une importance cruciale dans la construction d’une biopile microbienne. Le graphène est considéré comme un matériau prometteur avec de grandes possibilités d’application dans de nombreux domaines tels que les batteries Li-ion, les cellules photovoltaïques et les super condensateurs électrochimiques en raison de sa structure nanométrique. Ainsi, la modification de surface par de l’oxyde de graphène réduit a été appliquée à la construction d’anodes pour biopiles microbiennes. La cathode abiotique a aussi été étudiée puisqu’elle présente souvent une limitation cinétique vis-à-vis de la réduction de l’oxygène. Les potentialités des complexes organométalliques, et en particulier les phthalocyanines de nickel, ont été étudiés et appliquées à la construction d’une cathode pour biopile. Ainsi, une biopile hybride à deux compartiments a été construite en combinant une bioanode en mousse d’acier inoxydable modifiée par de l’oxyde de graphène réduite et une cathode en feutre de carbone modifiée avec de la phthalocyanine de nickel. La biopile microbienne ainsi construite utilise du lixiviat de terreau, comme source de microorganismes, pour le développement d’un biofilm électroactif à l’anode et présente une bonne stabilité dans le temps. Le graphène a permis d’obtenir une densité de puissance stable pendant une période 40 jours (24.8 mW/m² en présence d’oxygène pur). La cathode présentée dans ce travail a permis d’obtenir une densité de puissance supérieure à une cathode de platine (7.5 fois supérieur). Par ailleurs, un nouveau design de biopile à deux compartiments a été construit, afin de produire de l’électricité à partir d’une souche pure : Pseudomonas aeruginosa qui est connu pour la formation de biofilm électroactive. Un nouveau design a été proposé, permettant de travailler à alimentation constante et non plus en batch comme cela se fait de manière classique. Cette configuration permet de ne plus avoir de diminution de courant liée à un manque d’apport en carburant. Différents paramètres ont ainsi été explorés tel que le débit d’alimentation, la consommation en glucose dans le compartiment anodique, la variation de pH au cours du temps ainsi que l’évolution de la biomasse. Une première approche d’étude de corrélation de ces différents paramètres est proposée. / Microbial fuel cell (MFC) has been considered as a renewable energy source which uses bacteria to convert chemical energy into electricity. Since the anode, as the electron acceptor for the electroactive bacteria, directly interacts with microorganisms, the selection of high performance anode materials is of crucial importance in the design of a MFC. Recently, graphene has been considered as the intriguing material, attracting strong scientific and technological interest with great application potentials in various fields, such as lithium ion batteries, solar cells and electrochemical super-capacitors, for its unique nanostructure and extraordinary properties. Therefore, surface modification using reduced graphene oxide has been investigated for the construction of anodes. An abiotic cathode has also been investigated since it often has a kinetic limitation regarding the oxygen reduction reaction. The potential of the use of organometallics complexes, and more particularly nickel phthalocyanines (poly-NiTSPc), has been studied and applied to the fabrication of cathodes for biofuel cells applications. Thereby, a dual chamber hybrid MFC has been constructed combining a reduced graphene oxide modified bioanode with a chemical poly-NiTSPc modified carbon felt. This MFC uses compost garden leachate, as source of microorganisms, for the growth of an electroactive biofilm onto the anode and presents an excellent lifetime. Indeed, graphene allowed to obtain a power density stable for 40 fays (24.8 mW/m² with pure oxygen). When the modified carbon felt was used as cathode, the power densities obtained were 7.5 higher than the use of platinum cathode. Furthermore, a new design of a dual chamber MFC has been built up in order to work with a constant flow, to supply continuously substrates to the biofilm formed onto the anode from a pure strain, Pseudomonas aeruginosa, and to avoid to work in a batch as it is usually done. The interest of this configuration is to prevent any current loss due to a lack in supply of substrates. Using this bioreactor as a MFC, different parameters have been explored such as the feed rate and the glucose consumption in the anodic compartment, the evolution of the pH as well as the biomass between the entrance and the exit of the chamber. A first study of the correlation between all these parameters has been proposed.
22

Développement de biocathodes pour biopiles enzymatiques utilisant la laccase / Development of an enzymatic cathode biofuel cell using laccase

Blout, Mohamed Achraf 17 October 2017 (has links)
Les biopiles enzymatiques constituent une alternative intéressante de production d'électricité renouvelable. On s'est intéressé dans ce travail au compartiment cathodique d'une biopile utilisant la laccase, une oxydase multi-cuivres, comme biocatalyseur pour la réduction de l'oxygène (ORR) par transfert direct des électrons. Plusieurs stratégies ont été mises en œuvre afin d'optimiser la cinétique de l'ORR sur électrode de graphite. Une des stratégies a consisté à déposer un film mince de nitrure de carbone amorphe (a-CNx) sur le graphite. La présence de groupements amines de surface a ensuite permis le greffage covalent de la laccase. Des groupements carboxyliques peuvent également être introduits par un traitement électrochimique. En alliant plusieurs techniques de caractérisation, notamment des mesures d'impédance, on a démontré que notre système se comporte comme un réseau de microélectrodes. Pour ce type d'électrode on a mesuré une densité de courant maximale de -44,6 µA/cm2. Dans une autre stratégie, la surface du graphite a été nanostructurée par formation de nanowalls de carbone (CNWs) par dépôt chimique en phase vapeur assisté par plasma. On a optimisé les conditions du traitement ultérieur de fonctionnalisation de la surface par APPJ en ayant recours à des plans d'expériences, ce qui a permis d'atteindre des densités de courants de l'ordre de -1 mA/cm2. On a également étudié l'orientation et la cinétique de greffage de l'enzyme sur une surface d'or en utilisant la technique PM-IRRAS. / Enzymatic biofuel cells are an attractive alternative for renewable electricity generation. In this work, we are focusing on the cathodic compartment of a biofuel cell using laccase, a multi-copper oxidase, as biocatalysts for the oxygen reduction reaction (ORR) by direct electron transfer of electrons. Several strategies have been used to optimize the kinetic of ORR on graphite electrode. One strategy was to deposit thin film of amorphous carbon nitride (a-CNx) on graphite. The presence of surface amine groups then allowed the covalent grafting of the laccase. Carboxylic groups can also be produced by an electrochemical treatment. By combining several characterisation techniques, especially impedance measurements, we have demonstrated that our system behaves like microelectrodes network. For this type of electrode, we have measured a maximal current density equal to -44,6 µA/cm2. In another strategy, the surface of graphite was nanostructured by forming carbon nanowalls (CNWs) using the plasma-enhanced chemical vapour deposition technique in a CO/H2 microwave discharge. We have optimized then the APPJ functionalization conditions using experiments design. We reached current densities of the order of -1 mA/cm2. We have also studied the orientation and the kinetic of enzyme immobilisation on gold surface using PM-IRRAS technique.
23

L’hydrogénase [Ni-Fe] multi-tolérante d’Aquifex aeolicus : de l’immobilisation fonctionnelle à la biopile H2/O2

Ciaccafava, Alexandre 18 December 2012 (has links)
Les hydrogénases sont les enzymes responsables de la conversion de l'H2. De part leur efficacité et spécificité vis-à-vis de l'oxydation de l'H2, elles apparaissent comme des biocatalyseurs potentiels dans les biopiles à combustible. Dans cet objectif, nous avons étudié l'immobilisation fonctionnelle sur diverses électrodes de l'hydrogénase membranaire tolérante à l'O2 de la bactérie hyperthermophile Aquifex aeolicus. Par une approche couplée d'électrochimie, de microscopie et de spectroscopie, il est montré que l'orientation de l'hydrogénase sur une électrode n'est pas contrôlée par des interactions électrostatiques mais hydrophobes. Ce contrôle est lié à l'environnement spécifique du dernier relais électronique en surface de l'enzyme. En particulier, l'hélice transmembranaire hydrophobe entourée de détergent est impliquée dans l'immobilisation. Cette orientation spécifique induit la nécessité d'un médiateur redox pour l'oxydation de l'H2 sur une interface hydrophobe. A contrario, l'hydrogénase adopte une multitude d'orientations sur surfaces chargées. Dans ces conditions, une connexion directe efficace des enzymes est obtenue, mais aussi l'augmentation du courant global par médiation de l'oxydation de l'H2. La définition des paramètres d'immobilisation de l'hydrogénase, a permis de développer des interfaces électrochimiques propres à l'augmentation des courants. En couplant une biocathode basée sur la bilirubin oxidase pour la réduction de l'O2, une biopile H2/O2 a été construite basée à l'anode sur l'hydrogénase d'Aquifex aeolicus. / Hydrogenases are the key enzymes for H2 conversion in many microorganisms. They present high specificity and efficiency towards H2 oxidations. Consequently, they appear as attracting biocatalysts in view of the development of biofuel cells. Within that goal, we have studied in this work the functional immobilization of O2-tolerant [NiFe] hydrogenase from the hyperthermophilic bacterium Aquifex aeolicus. Using electrochemistry, microscopy and spectroscopy, including PM-IRRAS, it is demonstrated that hydrogenase orientation on electrode interface is not controlled by electrostatic interactions but by hydrophobic interactions. The control of the orientation is driven by the environment of the last electron relay located at the surface of the enzyme. The hydrophobic transmembrane helix which is surrounded by neutral detergent is directly involved in the immobilization process. This specific orientation on hydrophobic interface induces the need for a redox mediator in order to achieve H2 oxidation. Conversely, hydrogenase adopts multiple orientations on charged interfaces. As a consequence, a direct and efficient connexion of enzymes is obtained, but also the increase in oxidation current is obtained due the mediated electrocatalysis. The determination of the best parameters for hydrogenase immobilization has allowed to develop new electrochemical interfaces, with increased current densities for H2 oxidation, and increased bioelectrode stability. By coupling a biocathode based on bilirubin oxidase for O2 reduction, a H2/O2 biofuel cell has been built with Aquifex aeolicus hydrogenase as the bioanode.
24

Nouveaux analogues de substrats de déshydrogénases pour le développement d’interfaces enzymes/électrodes innovantes / New synthetic substrates used by dehydrogenases for the development of innovative enzyme/electrode interfaces

Carter, Julie 04 November 2016 (has links)
Les systèmes bioélectroniques tels que les biopiles enzymatiques nécessitant souvent l'utilisation des assemblages moléculaires complexes comprenant le cofacteur de l'enzyme, des agents de couplage et des médiateurs électrochimiques. Afin de les simplifier, nous avons remplacé ces différents partenaires par 13 analogues simples à synthétiser après identification par criblage in silico. Le noyau aromatique est couplé à un noyau aromatique et puis un médiateur électrochimique est couplé à celui-ci. Les produits sont des poudres de couleurs variées (rose, rouge). Le rendement de la première étape est de 83% avec une pureté d'environ 92%. Le rendement de la seconde étape est compris entre 45% et 65% avec une pureté de 97%. Ces analogues ont été caractérisés chimiquement (RMN, spectrométrie de masse) et électrochimiquement (voltammétrie cyclique et spectroélectrochimie). Les activités de deux enzymes, la formiate déshydrogénase (FDH) et l'alcool déshydrogénase de foie de cheval (HLADH), et d'un catalyseur organométallique, le [Cp*Rh(bpy)(H2O)]2+, ont été évaluées avec ces analogues. De faibles activités ont été observées en présence de l'HLADH avec 4 analogues et en présence de la FDH avec un seul analogue. Au contraire aux enzymes, la réduction d'un médiateur a pu été confirmée en présence du catalyseur [Cp*Rh(bpy)(H2O)]2+ par voltammétrie cyclique. La FDH native n'est pas adaptée à fonctionner avec ces nouveaux substrats solubles dans un LI, le [MMIm][Me2PO4]. Une FDH tolérante (N187S/T321S) au [MMIm][Me2PO4] précédemment obtenue par évolution dirigée a été donc étudiée en isolant les simples mutants N187S et T321S. Le double mutant N187S/T321S et le simple mutant N187S sont 4 fois plus actifs en solution aqueuse et en présence de LI. Des analyses par spectroscopie de fluorescence ont montré que la simple mutation N187S favorise la stabilité du dimère de FDH en modifiant le pKa de l'acide aminé E163. Celui-ci est impliqué dans la thermostabilité et la tolérance des FDHs aux LIs / Bioelectrical systems, such as enzymatic biofuel cells, often require a molecular construction complex comprising the enzyme cofactor, intermediary molecules and electrochemical mediators. In order to simplify them, we have replaced these different partners by 13 analogs that are simple to synthesize after identification by screening in silico. The nicotinamide ring is coupled to an aromatic moiety and an electrochemical mediator is then coupled to it as well, resulting in various colored powders (pink, red). The first step' s yield is around 83% with a purity of approximately 92%. The second step's yield is comprised between 45% and 65% with a purity of 97%. The analogs were characterized chemically (NMR, mass spectrometry) and electrochemically (cyclic voltammetry, spectroelectrochemistry). The activities of two enzymes, the formate dehydrogenase (FDH) and the horse liver alcohol dehydrogenase (HLADH), and an organometallic catalyst, [Cp*Rh(bpy)H2O]2+, were evaluated with these analogs. Weak activities were observed for 4 analogs using the HLADH and 1 analog using the FDH. Unlike the enzymes, the reduction of a conjugated mediator was confirmed with the catalyst [Cp*Rh(bpy)H2O]2+ using cyclic voltammetry. The wild type FDH is not adapted to function with these new substrates, which can be solubilized in an IL such as [MMIm][Me2PO4]. An FDH (N187S/T321S) shown to be tolerant to [MMIm][Me2PO4], and obtained previously by directed evolution, was studied by isolating the two single mutants, N187S and T321S. The double mutant N187S/T321S and the mutant N187S are 4 times more active in aqueous solution and in [MMIm][Me2PO4]. Fluorescence spectroscopy analyses showed that the single mutation N187S favorises FDH dimer stability by modifying the pKa of the amino acid E163. The latter is involved in FDH thermal stability and tolerance in ILs
25

Biorremediação de solos contaminados com hidrocarbonetos totais de petróleo - enfoque na aplicação do processo terraferm

Berger, Thomas Michael January 2005 (has links)
Bodenkontaminationen durch Mineralölkohlenwasserstoffe sind ein weltweites Umweltproblem. Die Kontaminatiosquellen stehen im Zusammenhang mit Förderung, Lagerung, Transport, Verteilung und Endlagerung von Erdöl und Erdölprodukten. Brasilien beginnt zurzeit einen Prozess der Altlastenerfassung und –erkundung und in Konsequenz dessen auch die Suche nach geeigneten Sanierungstechniken. Biologische Prozesse spielen eine immer stärkere Rolle insbesondere bei der Sanierung von Bodenkontaminationen mit organischen Substanzen. Diese Prozesse gelten als “ökologisch korrekter” und sind im Vergleich mit anderen Techniken mit geringeren Kosten und technischen Aufwand durchführbar. Ziel dieser Arbeit war es, die Anwendungsmöglichkeiten der biologischen Bodensanierung mittels des Terraferm® Verfahrens unter den Umweltbedingungen des Bundesstaates São Paulo, Brasilien zu überprüfen. Zu diesem Zweck wurde der Boden einer MKW-kontaminierte Fläche (Mina de Argila) in der Raffinerie REPLAN der PETROBRÁS S/A in Paulínia -SP ausgekoffert. Es wurden zehn Bodenproben in Bezug auf ihre physikalisch-chemischen Eigenschaften MKW, PAK, BTEX, Metalle (Cr, Zn, Pb, Ni, Cu, Cd, As, Hg, Fe, Ta), Wassergehalt, pH, Korngröße analysiert. Drei Proben mit durchschnittlichen MKW-gehalten wurden zur Überprüfung der biologischen Sanierbarkeit und der Bestimmung der Kontrollparameter für den später Sanierungsdurchführung Säulenversuchen unterzogen. Insgesamt wurden 72.384t kontaminierten Bodens ausgekoffert, wovon 21.050t der Abfallklasse II (nach NBR 10004) zugeordnet wurden und direkt auf eine Mülldeponie verbracht wurden. Es wurden 51.334t der Abfallklasse 1 in die Bodenreinigungsanlage der Firmen SAPOTEC/ESTRE in Paulínia - SP mittels des Terraferm® Verfahrens behandelt. Dieses Verfahren ist darauf ausgelegt, alle für den biologischen Abbau nötigen Prozessparameter im Optimum zu halten. Die Behandlung erfolgt in Hallen auf versiegeltem Untergrund und die dabei freigesetzten Schad- und Geruchsstoffe werden gefasst und einer Abluftreinigung zugeführt. Nach der Vorbehandlung (Aussortierung von Störstoffen, Zugabe von Strukturmaterial, Durchmischung) mittels speziellem Aufbereitungsaggregat wurden insgesamt elf Behandlungsmieten aufgesetzt. Der Sauerstoffgehalt, Bodenfeuchte und Nährstoffgehalte wurden im Optimalbereich gehalten. Die Analysen und die Säulenversuche bestätigten die biologische Sanierbarkeit des Bodens. Die Abbauraten in den Säulenversuchen lagenzwischen 70,2% und 88,6% in 14 Tagen. Diese hohen Abbauraten lassen sich durch die Zusammensetzung der MKW begründen, die sich hauptsächlich aus gut abbaubaren n-Alkanen und iso-Alkanen bestehen. Die durchschnittliche Abbaurate bei den elf Behandlungsmieten lag bei 80,88%, wobei die niedrigste bei 54,71% und die höchste Abbaurate bei 97,97% lagen. Die statistische Auswertung ergab, dass sich die Mittelwerte der MKW-gehalte während der Behandlung signifikant voneinander unterscheiden (<0,01). Die im Rahmen dieser Arbeit durchgeführten Versuche bestätigen den erfolgreichen Einsatz des Terraferm® Verfahrens unter Umweltbedingungen des Bundesstaates São Paulo, Brasilien. Die starke Variabilität der Abbauraten in den Behandlungsmieten deutet aber auf einen weiteren Forschungsbedarf, insbesondere hinsichtlich des Temperatur-einflusses, hin. / Contaminações de solos com hidrocarbonetos de petróleo são um problema ambiental com abrangência mundial devido à alta demanda de produtos refinados de petróleo. As fontes são múltiplas e estão relacionadas à exploração, produção, armazenamento, transporte, distribuição e à destinação final de petróleo e seus derivados. Hoje o Brasil está iniciando um processo de avaliação e cadastramento de suas áreas contaminadas e, conseqüentemente, está procurando alternativas para a remediação das mesmas. Processos biológicos estão ganhando cada vez mais importância no tratamento, especialmente de solos contaminados com compostos orgânicos. Estes métodos são favorecidos por serem mais limpos, com custos baixos e de mais fácil aplicação em escala industrial. Assim, com o objetivo de verificar a aplicabilidade da biorremediação através do processo Terraferm® às condições ambientais do Estado de São Paulo, Brasil, foi realizada a remediação ex situ de uma área contaminada com TPH, chamada Mina de Argila na Refinaria de Paulínia – REPLAN da PETROBRÁS S/A, em Paulínia - SP. Foram analisadas dez amostras de solo contaminado em relação aos parâmetros físico-químicos TPH, PAH, BTEX, metais (Cr, Zn, Pb, Ni, Cu, Cd, As, Hg, Fe, Ta), umidade, pH, oxigênio e granulometria. Três amostras com valores médios de TPH foram submetidas a ensaios de coluna para verificação da biotratabilidade do material e para definição de parâmetros de controle do processo em escala industrial. Foram removidos um total de 72.384t de material contaminado. Deste total, 21.050t foram classificadas como resíduo classe II segundo a NBR 10004 e encaminhadas para um aterro sanitário, e 51.334t foram classificadas como resíduo classe I, sendo destinadas à estação de biorremediação das empresas SAPOTEC/ESTRE, em Paulínia - SP. O solo contaminado foi tratado com o processo Terraferm®, que visa à otimização dos parâmetros que influenciam diretamente a atividade microbiana necessária para a biodegradação. O tratamento é feito em galpões com piso impermeabilizado e com um sistema de captação e tratamento das emissões geradas durante o processo de biodegradação. Após o pré-tratamento em máquina especial, que consiste na separação dos materiais não-tratáveis, na homogeneização e na adição de material estrutural, o solo contaminado foi colocado em onze pilhas de tratamento. Os fatores chave como o teor de oxigênio, a umidade e os nutrientes foram mantidos nas faixas consideradas ótimas. A caracterização química e o ensaio de coluna comprovaram a biotratabilidade do solo. Noensaio em coluna, obteve-se taxas de degradação entre 70,2% e 88,6% em 14 dias. Essas taxas altas são explicadas pela composição do TPH que consiste, neste caso, basicamente de n-alcanos e iso-alcanos considerados de fácil degradação biológica. A taxa média de degradação obtida no tratamento das onze pilhas foi de 80,88%, sendo a menor de 54,71% e a maior de 97,97%. Na análise estatística, verificou-se que as médias das concentrações de TPH durante cada período de tratamento diferem significativamente (<0,01). O trabalho conclui que o processo Terraferm® foi aplicado com sucesso nas condições ambientais do Estado de São Paulo, Brasil. Entretanto, os resultados do tratamento mostram uma alta variabilidade das taxas de degradação nas pilhas, que indica a necessidade de novas pesquisas, especialmente sobre a influência da temperatura no processo. / Soil contaminations with petroleum hydrocarbons are a worldwide environmental problem due to the high demand for refined petroleum products. Contamination sources are multiple and related to the exploration, production, storage, transportation, distribution, and final disposal of petroleum and its derivatives. Nowadays Brazil is starting to assess and record its contaminated areas and consequently search for alternatives for their remediation. Biological processes are gaining more and more importance, specially in the treatment of soils contaminated by organic compounds. These methods are favored for being cleaner, with lower costs, and more easily applicable to industrial scale. Therefore, with the objective of verifying the applicability of bioremediation to the environmental conditions of São Paulo State, Brazil, the ex situ remediation of a contaminated area by TPH was carried out by using the Terraferm® process. The area called Mina de Argila was located in the Paulínia Refinery – REPLAN, which belongs to PETROBRÁS S/A (the country's leader in the exploration, production, and distribution of petroleum products). Ten samples of contaminated soil were analyzed in relation to the physical-chemical parameters TPH, PAH, BTEX, metals (Cr, Zn, Pb, Ni, Cu, Cd, As, Hg, Fe, Ta), humidity, pH, oxygen and texture. Three samples with average values of TPH were submitted to column tests in order to assess the material biotreatability and define the control parameters of the process on industrial scale. A total of 72,384t of contaminated soil were removed. From this total, 21,050t were classified as class II waste according to NBR 10004 and sent to a landfill, and 51,334t were classified as class I waste and sent to the bioremediation plant of the companies SAPOTEC/ESTRE, in Paulínia – São Paulo State. The contaminated soil was treated with the Terraferm® process whose purpose is to optimize the parameters which directly influence the microbial activity necessary for biodegradation. The treatment was carried out in sheds with waterproof floor and a collection and treatment system for the emissions generated in the biodegradation process. After the treatment in a special machine, which consists in separating non-treatable materials, homogenizing, and adding structural material, the soil was placed into eleven treatment piles. The oxygen content, humidity, and nutrients were kept within a range considered optimum. The chemical characterization and the column test proved the soil biotreatability. In the column test, the degradation rates were between 70.2% and 88.6% in 14 days. These high rates are due to the TPHcomposition, which in this case basically consists in n-alkenes and iso-alkenes of easy biological degradation. The average degradation rate verified in the treatment of the eleven piles was of 80.88%, the lowest being 54.71% and the highest 97.97%. In the statistical analysis, it was verified that the average concentrations of TPH during each treatment period differ significantly (<0.01). The conclusion of this work is that the Terraferm® process was successfully applied to the environmental conditions of São Paulo State. However, the treatment results show a high variability in the degradation rates of the piles, which indicates the need for further research, specially on the influence of temperature on the process.
26

Transformation électrocatalytique de sucres couplée à la réduction enzymatique de l'oxygène moléculaire pour la production d'énergie / Electrocatalytique transformation of carbohydrates combined with enzymatic molecular dioxygen reduction for sustainable energy production

Holade, Yaovi 26 June 2015 (has links)
Le développement de générateurs d'énergie pour alimenter des micro-appareils électroniques implantés est devenu une option inéluctable. L'objectif général qui a orienté ces recherches était l'élaboration et les études approfondies des propriétés nanomatériaux métalliques utilisables comme électrocatalyseurs afin de convertir l'énergie chimique en énergie électrique. Les nanomatériaux sont obtenus par la méthode de synthèse : Bromide Anion Exchange (BAE) qui a été scrupuleusement revisitée puis optimisée avec un agent réducteur faible (AA) et fort (NaBH4). Cette voie de synthèse a permis d'obtenir (rendement ≥ 90 %) des matériaux plurimétalliques composés d'or, de platine et de palladium. Un prétraitement des supports commerciaux des nanoparticules a permis d’augmenter leurs surfaces, spécifique et active respectivement de 48 et 120 %. Les études (électro)analytiques ont permis d'identifier les intermédiaires et produits de réaction du combustible. Le glucose s'oxyde sans rupture de la liaison C-C pour donner majoritairement du gluconate avec une sélectivité ≥ 88 %. Les tests réalisés en biopile hybride (cathode enzymatique) indiquent que les catalyseurs Au/C-AA et Au60Pt40/C-NaBH4 sont les meilleures anodes abiotiques (Pmax = 125 µW·cm-2 à 0,4 V). Par ailleurs, les piles sans membrane séparatrice et sans enzyme ont été réalisées avec succès pour activer un stimulateur cardiaque et un système de transmission d'information en mode "Wifi". Ces dispositifs, rapportés pour la première fois, ouvrent une ère nouvelle pour la conception de convertisseurs d'énergie pour alimenter les implants médicaux ou des appareils sans fil de détection et de surveillance. / The development of energy converters to power implanted micro-electronic devices has become a cornerstone item. The whole target which has governed this research was the design of advanced nanostructures metals used as electrocatalysts for converting chemical energy into electrical one. These nanomaterials were obtained by the synthesis method: Bromide Anion Exchange (BAE) that has been carefully revisited and optimized, using a weak reducing agent (AA) and strong one (NaBH4). It allowed to prepare efficiently various plurimetallic nanomaterials composed of gold, platinum and palladium (yield ≥ 90%). A thermal pretreatment of commercial carbon supports of nanoparticles has highly boosted their specific and active surface areas with a gain of 48 and 120%. Based on in situ and ex-situ (electro)analytical methods, the intermediates and final reaction products of the fuel oxidation were identified. Glucose electrooxidation occurs without C-C bond cleavage and gives predominantly gluconate with a selectivity ≥ 88 %. Results from the hybrid biofuel cell tests (with an enzyme as cathode catalyst) indicate that Au/C-AA and Au60Pt40/C-NaBH4 are the best abiotic anodes (Pmax = 125 µW cm-2 at 0.4 V cell voltage). A fuel cell without separating membrane and enzyme has been successfully constructed and used to activate a pacemaker and an information transmission system based on "wireless" mode. These last experiments, reported for the first time as using nanomaterials in membrane-less configuration, open a new approach in the design of advanced energy converters to power medical implants or remote systems for detection and electronic monitoring.
27

Biorremediação de solos contaminados com hidrocarbonetos totais de petróleo - enfoque na aplicação do processo terraferm

Berger, Thomas Michael January 2005 (has links)
Bodenkontaminationen durch Mineralölkohlenwasserstoffe sind ein weltweites Umweltproblem. Die Kontaminatiosquellen stehen im Zusammenhang mit Förderung, Lagerung, Transport, Verteilung und Endlagerung von Erdöl und Erdölprodukten. Brasilien beginnt zurzeit einen Prozess der Altlastenerfassung und –erkundung und in Konsequenz dessen auch die Suche nach geeigneten Sanierungstechniken. Biologische Prozesse spielen eine immer stärkere Rolle insbesondere bei der Sanierung von Bodenkontaminationen mit organischen Substanzen. Diese Prozesse gelten als “ökologisch korrekter” und sind im Vergleich mit anderen Techniken mit geringeren Kosten und technischen Aufwand durchführbar. Ziel dieser Arbeit war es, die Anwendungsmöglichkeiten der biologischen Bodensanierung mittels des Terraferm® Verfahrens unter den Umweltbedingungen des Bundesstaates São Paulo, Brasilien zu überprüfen. Zu diesem Zweck wurde der Boden einer MKW-kontaminierte Fläche (Mina de Argila) in der Raffinerie REPLAN der PETROBRÁS S/A in Paulínia -SP ausgekoffert. Es wurden zehn Bodenproben in Bezug auf ihre physikalisch-chemischen Eigenschaften MKW, PAK, BTEX, Metalle (Cr, Zn, Pb, Ni, Cu, Cd, As, Hg, Fe, Ta), Wassergehalt, pH, Korngröße analysiert. Drei Proben mit durchschnittlichen MKW-gehalten wurden zur Überprüfung der biologischen Sanierbarkeit und der Bestimmung der Kontrollparameter für den später Sanierungsdurchführung Säulenversuchen unterzogen. Insgesamt wurden 72.384t kontaminierten Bodens ausgekoffert, wovon 21.050t der Abfallklasse II (nach NBR 10004) zugeordnet wurden und direkt auf eine Mülldeponie verbracht wurden. Es wurden 51.334t der Abfallklasse 1 in die Bodenreinigungsanlage der Firmen SAPOTEC/ESTRE in Paulínia - SP mittels des Terraferm® Verfahrens behandelt. Dieses Verfahren ist darauf ausgelegt, alle für den biologischen Abbau nötigen Prozessparameter im Optimum zu halten. Die Behandlung erfolgt in Hallen auf versiegeltem Untergrund und die dabei freigesetzten Schad- und Geruchsstoffe werden gefasst und einer Abluftreinigung zugeführt. Nach der Vorbehandlung (Aussortierung von Störstoffen, Zugabe von Strukturmaterial, Durchmischung) mittels speziellem Aufbereitungsaggregat wurden insgesamt elf Behandlungsmieten aufgesetzt. Der Sauerstoffgehalt, Bodenfeuchte und Nährstoffgehalte wurden im Optimalbereich gehalten. Die Analysen und die Säulenversuche bestätigten die biologische Sanierbarkeit des Bodens. Die Abbauraten in den Säulenversuchen lagenzwischen 70,2% und 88,6% in 14 Tagen. Diese hohen Abbauraten lassen sich durch die Zusammensetzung der MKW begründen, die sich hauptsächlich aus gut abbaubaren n-Alkanen und iso-Alkanen bestehen. Die durchschnittliche Abbaurate bei den elf Behandlungsmieten lag bei 80,88%, wobei die niedrigste bei 54,71% und die höchste Abbaurate bei 97,97% lagen. Die statistische Auswertung ergab, dass sich die Mittelwerte der MKW-gehalte während der Behandlung signifikant voneinander unterscheiden (<0,01). Die im Rahmen dieser Arbeit durchgeführten Versuche bestätigen den erfolgreichen Einsatz des Terraferm® Verfahrens unter Umweltbedingungen des Bundesstaates São Paulo, Brasilien. Die starke Variabilität der Abbauraten in den Behandlungsmieten deutet aber auf einen weiteren Forschungsbedarf, insbesondere hinsichtlich des Temperatur-einflusses, hin. / Contaminações de solos com hidrocarbonetos de petróleo são um problema ambiental com abrangência mundial devido à alta demanda de produtos refinados de petróleo. As fontes são múltiplas e estão relacionadas à exploração, produção, armazenamento, transporte, distribuição e à destinação final de petróleo e seus derivados. Hoje o Brasil está iniciando um processo de avaliação e cadastramento de suas áreas contaminadas e, conseqüentemente, está procurando alternativas para a remediação das mesmas. Processos biológicos estão ganhando cada vez mais importância no tratamento, especialmente de solos contaminados com compostos orgânicos. Estes métodos são favorecidos por serem mais limpos, com custos baixos e de mais fácil aplicação em escala industrial. Assim, com o objetivo de verificar a aplicabilidade da biorremediação através do processo Terraferm® às condições ambientais do Estado de São Paulo, Brasil, foi realizada a remediação ex situ de uma área contaminada com TPH, chamada Mina de Argila na Refinaria de Paulínia – REPLAN da PETROBRÁS S/A, em Paulínia - SP. Foram analisadas dez amostras de solo contaminado em relação aos parâmetros físico-químicos TPH, PAH, BTEX, metais (Cr, Zn, Pb, Ni, Cu, Cd, As, Hg, Fe, Ta), umidade, pH, oxigênio e granulometria. Três amostras com valores médios de TPH foram submetidas a ensaios de coluna para verificação da biotratabilidade do material e para definição de parâmetros de controle do processo em escala industrial. Foram removidos um total de 72.384t de material contaminado. Deste total, 21.050t foram classificadas como resíduo classe II segundo a NBR 10004 e encaminhadas para um aterro sanitário, e 51.334t foram classificadas como resíduo classe I, sendo destinadas à estação de biorremediação das empresas SAPOTEC/ESTRE, em Paulínia - SP. O solo contaminado foi tratado com o processo Terraferm®, que visa à otimização dos parâmetros que influenciam diretamente a atividade microbiana necessária para a biodegradação. O tratamento é feito em galpões com piso impermeabilizado e com um sistema de captação e tratamento das emissões geradas durante o processo de biodegradação. Após o pré-tratamento em máquina especial, que consiste na separação dos materiais não-tratáveis, na homogeneização e na adição de material estrutural, o solo contaminado foi colocado em onze pilhas de tratamento. Os fatores chave como o teor de oxigênio, a umidade e os nutrientes foram mantidos nas faixas consideradas ótimas. A caracterização química e o ensaio de coluna comprovaram a biotratabilidade do solo. Noensaio em coluna, obteve-se taxas de degradação entre 70,2% e 88,6% em 14 dias. Essas taxas altas são explicadas pela composição do TPH que consiste, neste caso, basicamente de n-alcanos e iso-alcanos considerados de fácil degradação biológica. A taxa média de degradação obtida no tratamento das onze pilhas foi de 80,88%, sendo a menor de 54,71% e a maior de 97,97%. Na análise estatística, verificou-se que as médias das concentrações de TPH durante cada período de tratamento diferem significativamente (<0,01). O trabalho conclui que o processo Terraferm® foi aplicado com sucesso nas condições ambientais do Estado de São Paulo, Brasil. Entretanto, os resultados do tratamento mostram uma alta variabilidade das taxas de degradação nas pilhas, que indica a necessidade de novas pesquisas, especialmente sobre a influência da temperatura no processo. / Soil contaminations with petroleum hydrocarbons are a worldwide environmental problem due to the high demand for refined petroleum products. Contamination sources are multiple and related to the exploration, production, storage, transportation, distribution, and final disposal of petroleum and its derivatives. Nowadays Brazil is starting to assess and record its contaminated areas and consequently search for alternatives for their remediation. Biological processes are gaining more and more importance, specially in the treatment of soils contaminated by organic compounds. These methods are favored for being cleaner, with lower costs, and more easily applicable to industrial scale. Therefore, with the objective of verifying the applicability of bioremediation to the environmental conditions of São Paulo State, Brazil, the ex situ remediation of a contaminated area by TPH was carried out by using the Terraferm® process. The area called Mina de Argila was located in the Paulínia Refinery – REPLAN, which belongs to PETROBRÁS S/A (the country's leader in the exploration, production, and distribution of petroleum products). Ten samples of contaminated soil were analyzed in relation to the physical-chemical parameters TPH, PAH, BTEX, metals (Cr, Zn, Pb, Ni, Cu, Cd, As, Hg, Fe, Ta), humidity, pH, oxygen and texture. Three samples with average values of TPH were submitted to column tests in order to assess the material biotreatability and define the control parameters of the process on industrial scale. A total of 72,384t of contaminated soil were removed. From this total, 21,050t were classified as class II waste according to NBR 10004 and sent to a landfill, and 51,334t were classified as class I waste and sent to the bioremediation plant of the companies SAPOTEC/ESTRE, in Paulínia – São Paulo State. The contaminated soil was treated with the Terraferm® process whose purpose is to optimize the parameters which directly influence the microbial activity necessary for biodegradation. The treatment was carried out in sheds with waterproof floor and a collection and treatment system for the emissions generated in the biodegradation process. After the treatment in a special machine, which consists in separating non-treatable materials, homogenizing, and adding structural material, the soil was placed into eleven treatment piles. The oxygen content, humidity, and nutrients were kept within a range considered optimum. The chemical characterization and the column test proved the soil biotreatability. In the column test, the degradation rates were between 70.2% and 88.6% in 14 days. These high rates are due to the TPHcomposition, which in this case basically consists in n-alkenes and iso-alkenes of easy biological degradation. The average degradation rate verified in the treatment of the eleven piles was of 80.88%, the lowest being 54.71% and the highest 97.97%. In the statistical analysis, it was verified that the average concentrations of TPH during each treatment period differ significantly (<0.01). The conclusion of this work is that the Terraferm® process was successfully applied to the environmental conditions of São Paulo State. However, the treatment results show a high variability in the degradation rates of the piles, which indicates the need for further research, specially on the influence of temperature on the process.
28

Biorremediação de solos contaminados com hidrocarbonetos totais de petróleo - enfoque na aplicação do processo terraferm

Berger, Thomas Michael January 2005 (has links)
Bodenkontaminationen durch Mineralölkohlenwasserstoffe sind ein weltweites Umweltproblem. Die Kontaminatiosquellen stehen im Zusammenhang mit Förderung, Lagerung, Transport, Verteilung und Endlagerung von Erdöl und Erdölprodukten. Brasilien beginnt zurzeit einen Prozess der Altlastenerfassung und –erkundung und in Konsequenz dessen auch die Suche nach geeigneten Sanierungstechniken. Biologische Prozesse spielen eine immer stärkere Rolle insbesondere bei der Sanierung von Bodenkontaminationen mit organischen Substanzen. Diese Prozesse gelten als “ökologisch korrekter” und sind im Vergleich mit anderen Techniken mit geringeren Kosten und technischen Aufwand durchführbar. Ziel dieser Arbeit war es, die Anwendungsmöglichkeiten der biologischen Bodensanierung mittels des Terraferm® Verfahrens unter den Umweltbedingungen des Bundesstaates São Paulo, Brasilien zu überprüfen. Zu diesem Zweck wurde der Boden einer MKW-kontaminierte Fläche (Mina de Argila) in der Raffinerie REPLAN der PETROBRÁS S/A in Paulínia -SP ausgekoffert. Es wurden zehn Bodenproben in Bezug auf ihre physikalisch-chemischen Eigenschaften MKW, PAK, BTEX, Metalle (Cr, Zn, Pb, Ni, Cu, Cd, As, Hg, Fe, Ta), Wassergehalt, pH, Korngröße analysiert. Drei Proben mit durchschnittlichen MKW-gehalten wurden zur Überprüfung der biologischen Sanierbarkeit und der Bestimmung der Kontrollparameter für den später Sanierungsdurchführung Säulenversuchen unterzogen. Insgesamt wurden 72.384t kontaminierten Bodens ausgekoffert, wovon 21.050t der Abfallklasse II (nach NBR 10004) zugeordnet wurden und direkt auf eine Mülldeponie verbracht wurden. Es wurden 51.334t der Abfallklasse 1 in die Bodenreinigungsanlage der Firmen SAPOTEC/ESTRE in Paulínia - SP mittels des Terraferm® Verfahrens behandelt. Dieses Verfahren ist darauf ausgelegt, alle für den biologischen Abbau nötigen Prozessparameter im Optimum zu halten. Die Behandlung erfolgt in Hallen auf versiegeltem Untergrund und die dabei freigesetzten Schad- und Geruchsstoffe werden gefasst und einer Abluftreinigung zugeführt. Nach der Vorbehandlung (Aussortierung von Störstoffen, Zugabe von Strukturmaterial, Durchmischung) mittels speziellem Aufbereitungsaggregat wurden insgesamt elf Behandlungsmieten aufgesetzt. Der Sauerstoffgehalt, Bodenfeuchte und Nährstoffgehalte wurden im Optimalbereich gehalten. Die Analysen und die Säulenversuche bestätigten die biologische Sanierbarkeit des Bodens. Die Abbauraten in den Säulenversuchen lagenzwischen 70,2% und 88,6% in 14 Tagen. Diese hohen Abbauraten lassen sich durch die Zusammensetzung der MKW begründen, die sich hauptsächlich aus gut abbaubaren n-Alkanen und iso-Alkanen bestehen. Die durchschnittliche Abbaurate bei den elf Behandlungsmieten lag bei 80,88%, wobei die niedrigste bei 54,71% und die höchste Abbaurate bei 97,97% lagen. Die statistische Auswertung ergab, dass sich die Mittelwerte der MKW-gehalte während der Behandlung signifikant voneinander unterscheiden (<0,01). Die im Rahmen dieser Arbeit durchgeführten Versuche bestätigen den erfolgreichen Einsatz des Terraferm® Verfahrens unter Umweltbedingungen des Bundesstaates São Paulo, Brasilien. Die starke Variabilität der Abbauraten in den Behandlungsmieten deutet aber auf einen weiteren Forschungsbedarf, insbesondere hinsichtlich des Temperatur-einflusses, hin. / Contaminações de solos com hidrocarbonetos de petróleo são um problema ambiental com abrangência mundial devido à alta demanda de produtos refinados de petróleo. As fontes são múltiplas e estão relacionadas à exploração, produção, armazenamento, transporte, distribuição e à destinação final de petróleo e seus derivados. Hoje o Brasil está iniciando um processo de avaliação e cadastramento de suas áreas contaminadas e, conseqüentemente, está procurando alternativas para a remediação das mesmas. Processos biológicos estão ganhando cada vez mais importância no tratamento, especialmente de solos contaminados com compostos orgânicos. Estes métodos são favorecidos por serem mais limpos, com custos baixos e de mais fácil aplicação em escala industrial. Assim, com o objetivo de verificar a aplicabilidade da biorremediação através do processo Terraferm® às condições ambientais do Estado de São Paulo, Brasil, foi realizada a remediação ex situ de uma área contaminada com TPH, chamada Mina de Argila na Refinaria de Paulínia – REPLAN da PETROBRÁS S/A, em Paulínia - SP. Foram analisadas dez amostras de solo contaminado em relação aos parâmetros físico-químicos TPH, PAH, BTEX, metais (Cr, Zn, Pb, Ni, Cu, Cd, As, Hg, Fe, Ta), umidade, pH, oxigênio e granulometria. Três amostras com valores médios de TPH foram submetidas a ensaios de coluna para verificação da biotratabilidade do material e para definição de parâmetros de controle do processo em escala industrial. Foram removidos um total de 72.384t de material contaminado. Deste total, 21.050t foram classificadas como resíduo classe II segundo a NBR 10004 e encaminhadas para um aterro sanitário, e 51.334t foram classificadas como resíduo classe I, sendo destinadas à estação de biorremediação das empresas SAPOTEC/ESTRE, em Paulínia - SP. O solo contaminado foi tratado com o processo Terraferm®, que visa à otimização dos parâmetros que influenciam diretamente a atividade microbiana necessária para a biodegradação. O tratamento é feito em galpões com piso impermeabilizado e com um sistema de captação e tratamento das emissões geradas durante o processo de biodegradação. Após o pré-tratamento em máquina especial, que consiste na separação dos materiais não-tratáveis, na homogeneização e na adição de material estrutural, o solo contaminado foi colocado em onze pilhas de tratamento. Os fatores chave como o teor de oxigênio, a umidade e os nutrientes foram mantidos nas faixas consideradas ótimas. A caracterização química e o ensaio de coluna comprovaram a biotratabilidade do solo. Noensaio em coluna, obteve-se taxas de degradação entre 70,2% e 88,6% em 14 dias. Essas taxas altas são explicadas pela composição do TPH que consiste, neste caso, basicamente de n-alcanos e iso-alcanos considerados de fácil degradação biológica. A taxa média de degradação obtida no tratamento das onze pilhas foi de 80,88%, sendo a menor de 54,71% e a maior de 97,97%. Na análise estatística, verificou-se que as médias das concentrações de TPH durante cada período de tratamento diferem significativamente (<0,01). O trabalho conclui que o processo Terraferm® foi aplicado com sucesso nas condições ambientais do Estado de São Paulo, Brasil. Entretanto, os resultados do tratamento mostram uma alta variabilidade das taxas de degradação nas pilhas, que indica a necessidade de novas pesquisas, especialmente sobre a influência da temperatura no processo. / Soil contaminations with petroleum hydrocarbons are a worldwide environmental problem due to the high demand for refined petroleum products. Contamination sources are multiple and related to the exploration, production, storage, transportation, distribution, and final disposal of petroleum and its derivatives. Nowadays Brazil is starting to assess and record its contaminated areas and consequently search for alternatives for their remediation. Biological processes are gaining more and more importance, specially in the treatment of soils contaminated by organic compounds. These methods are favored for being cleaner, with lower costs, and more easily applicable to industrial scale. Therefore, with the objective of verifying the applicability of bioremediation to the environmental conditions of São Paulo State, Brazil, the ex situ remediation of a contaminated area by TPH was carried out by using the Terraferm® process. The area called Mina de Argila was located in the Paulínia Refinery – REPLAN, which belongs to PETROBRÁS S/A (the country's leader in the exploration, production, and distribution of petroleum products). Ten samples of contaminated soil were analyzed in relation to the physical-chemical parameters TPH, PAH, BTEX, metals (Cr, Zn, Pb, Ni, Cu, Cd, As, Hg, Fe, Ta), humidity, pH, oxygen and texture. Three samples with average values of TPH were submitted to column tests in order to assess the material biotreatability and define the control parameters of the process on industrial scale. A total of 72,384t of contaminated soil were removed. From this total, 21,050t were classified as class II waste according to NBR 10004 and sent to a landfill, and 51,334t were classified as class I waste and sent to the bioremediation plant of the companies SAPOTEC/ESTRE, in Paulínia – São Paulo State. The contaminated soil was treated with the Terraferm® process whose purpose is to optimize the parameters which directly influence the microbial activity necessary for biodegradation. The treatment was carried out in sheds with waterproof floor and a collection and treatment system for the emissions generated in the biodegradation process. After the treatment in a special machine, which consists in separating non-treatable materials, homogenizing, and adding structural material, the soil was placed into eleven treatment piles. The oxygen content, humidity, and nutrients were kept within a range considered optimum. The chemical characterization and the column test proved the soil biotreatability. In the column test, the degradation rates were between 70.2% and 88.6% in 14 days. These high rates are due to the TPHcomposition, which in this case basically consists in n-alkenes and iso-alkenes of easy biological degradation. The average degradation rate verified in the treatment of the eleven piles was of 80.88%, the lowest being 54.71% and the highest 97.97%. In the statistical analysis, it was verified that the average concentrations of TPH during each treatment period differ significantly (<0.01). The conclusion of this work is that the Terraferm® process was successfully applied to the environmental conditions of São Paulo State. However, the treatment results show a high variability in the degradation rates of the piles, which indicates the need for further research, specially on the influence of temperature on the process.
29

Biopiles enzymatiques H2-O2 : nanostructuration de l'interface électrochimique pour l'immobilisation des enzymes redox / H2/O2 Biofuel cells : nanostructuration of the electrochemical interface for the immobilisation of redox enzymes

De poulpiquet de Brescanvel, Anne 04 December 2014 (has links)
Dans la nature, la réduction de l'oxygène et l'oxydation de l'hydrogène sont catalysées par des enzymes oxydoréductases. Ces catalyseurs spécifiques, efficaces, renouvelables et biodégradables constituent une alternative séduisante au platine dans les piles à combustible. L'immobilisation à des interfaces nanostructurées de l'hydrogénase membranaire tolérante à l'oxygène de la bactérie hyperthermophile Aquifex aeolicus, et de la bilirubine oxydase thermostable de la bactérie Bacillus pumilus, a été étudiée dans ce sens.L'électrochimie et la dynamique moléculaire ont permis d'affiner le modèle d'orientation de l'hydrogénase sur les surfaces planes. L'efficacité de l'immobilisation de l'hydrogénase sur différents nanomatériaux carbonés (nano-particules, tubes et fibres de carbone) structurant la surface de l'électrode a été évaluée. Les nanofibres de carbone (CNFs) ont permis de former une bioanode efficace pour l'oxydation de l'H2 en l'absence de médiateurs redox. L'étude a souligné l'importance d'un transport efficace du substrat dans le film carboné mésoporeux. Les CNFs ont également été utilisées comme matériau d'électrode pour réaliser la 1ère connexion directe de la bilirubine oxydase. L'existence d'une forme resting alternative de l'enzyme, influencée par les ions chlorures, le pH et la température, a été mise en évidence. Une biocathode efficace pour la réduction de l'oxygène a été développée.Les deux électrodes thermostables ont permis le développement de la 1ère biopile H2/O2 qui délivre des densités de puissance supérieures au mW.cm-2 sur une large gamme de température. Ce résultat ouvre la voie à l'alimentation électrique de dispositifs de faibles puissances. / The oxygen reduction and the hydrogen oxidation reactions are realized in nature by oxidoreductase enzymes. These highly efficient, specific, renewable and biodegradable catalysts appear as a seducing alternative to platinum in fuel cell devices. The immobilization at nanostructured interfaces of the membrane-bound oxygen-tolerant hydrogenase from the hyperthermophilic bacterium Aquifex aeolicus, and of the thermostable bilirubin oxidase from Bacillus pumilus, has been studied within this objective.Electrochemistry and molecular dynamics have been used to validate the orientation model of the hydrogenase at planar electrodes. Hydrogenase immobilisation in 3D-networks based on various carbon materials (nanoparticles, nanotubes and nanofibers) has been especially studied. Fishbone carbon nanofibers were demonstrated to provide an efficient platform for mediatorless H2 oxidation. Mass transport inside the carbon mesoporous film has been especially studied and demonstrated to be one of the limitations of the catalytic efficiency. Direct electrical connection of bilirubin oxidase has also been realized for the first time thanks to its immobilization on carbon nanofiber films. An alternative resting form of the enzyme, influenced by chlorides, pH and temperature, has been evidenced. An efficient biocathode for the oxygen reduction reaction has been developed. Thanks to the two thermostable electrodes, the first H2-O2 bio fuel cell able to deliver power densities over 1 mW.cm-2 over a large temperature range has been developed. This result paves the way for the electrical alimentation of low-power devices.
30

Vers la conception d’une biopile enzymatique à glucose/oxygène efficace en milieu biologique / Towards the design of an enzymatic glucose/oxygen biofuel cell efficient in biological environment

Cadet, Marine 03 November 2015 (has links)
La première partie du travail présenté ici se concentre sur l’optimisation d’une cathode à oxygène. Tout d’abord, l’utilisation d’une nouvelle enzyme (la BOD de Magnaporthe oryzae) permet de multiplier le courant de réduction de l’oxygène en eau jusqu’à neuf fois. Ensuite la synthèse d’un polymère rédox adapté a permis d’améliorer le coefficient de diffusion des électrons dans l’hydrogel résultant en l’augmentation de la densité de courant générée. Enfin nous sommes passés d’uneélectrode de carbone en 2 dimensions à une fibre d’or poreuse tridimensionnelle. Après modification de cette fibre avec l’hydrogel rédox à base de BOD de M. oryzaenous avons évalué sa biocompatibilité : in vitro les tests ont montré l’absence totale de cytotoxicité et seule une très faible réponse inflammatoire ; in vivo aucune infection ne s’est déclarée pendant les 8 semaines d’implantation dans les souris etla formation d’une capsule fibrotique autour de l’électrode traduit sa bonne intégration dans les tissus de l’animal. La seconde partie concerne la biopile dans son intégralité, construite à partir de la cathode optimisée et d’une anode adaptée à base de GDH. Elle permet de générer jusqu’à 240 μW.cm-2 dans du tampon Pipes/CaCl2 à 5mM de glucose. La biopile a ensuite été testée dans du sang humain total. Un maximum de 129 μW.cm-2 a été obtenu dans un échantillon avec une glycémie de 8,2 mM sous air. De plus nous avons constaté que la densité de puissance délivrée augmente proportionnellement avec la glycémie des différents échantillons de sang testés, faisant de la biopile à la fois une source d’électricité et un biocapteur à glucose ce qui n’avait jamais été démontré auparavant. / The first part of the work presented here focuses on the optimization of an oxygen cathode. First, the use of a new enzyme (BOD from Magnaporthe oryzae) permit to increase the current of reduction of oxygen into water by a factor nine. Then the synthesis of a suitable redox polymer greatly improved the diffusion coefficient of electrons in the hydrogel, resulting in an increase of the current density. Finally we switched from a two-dimensional carbon electrode to a three-dimensional porous gold fiber. After modification of the fiber with the redox hydrogel based on BOD from M. oryzae, we assessed its biocompatibility: in vitro the tests showed the total absence of cytotoxicity and only a very low inflammatory response; in vivo noinfection appeared during the 8 weeks of implantation in mice and the formation of afibrotic capsule around the device reflects its successful integration into the animal tissues.The second part concerns the full biofuel cell, elaborated from the optimized cathode and an adapted GDH-based anode. It could generate up to 240 μW.cm-2 at 5mMglucose in Pipes/CaCl2 buffer. The biofuel cell was then tested in whole human blood. A maximum of 129 μW.cm-2 was obtained in a sample with 8,2 mM glycaemiaunder air. In addition we observed that the delivered power density increased proportionally with the glycaemia of the different blood samples tested, making the biofuel cell both a power source and a glucose biosensor at the same time which had never been shown before.

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