Marine microorganisms play a significant role in the cycling of nutrients in the open ocean through production, consumption, and degradation of organic matter (OM). Carbon (C), nitrogen (N), and phosphorus (P) are essential ingredients in every known recipe for life. However, the cycling of each of these elements proceeds at different rates such that the ratio of C:N:P can vary widely between particulate, dissolved, organic, and inorganic pools. To better understand the mechanisms controlling these transformations, this study investigated the bacterial remineralization of photosynthetically-derived organic matter derived from cultures of Trichodesmium IMS101, Thalassiosira weissflogii, Prochlorococcus MED4, and particulate material collected from the surface waters of an upwelling regime. Experiments were conducted at sea for a short duration (<6d) and in the laboratory for longer periods (<150 days). In all treatments, across experiments, we observed rapid and selective P remineralization independent of the type of organic material added. Full solubilization and remineralization of P typically occurred within a week. Conversely, N remineralization was slower, with only 39-45% of particulate N (PN) remineralized in shorter (6d) experiments and 55-75% of PN remineralized in <150d experiments. Nitrification was observed after 70-98 days depending on the remineralizing bacteria (isolated from either the Oregon coastal upwelling regime or the North Pacific Subtropical Gyre (NPSG). Notably, these events did not transform the full complement of ammonium to nitrate. This differential lability between N and P led to rapid changes in the N:P ratio of inorganic pools as organic matter was depolymerized by varying bacterial populations. The variable input of potentially limiting elements could have consequences for primary productivity and particle export. Finally, we observed that in short-term experiments with heterotrophic bacteria collected from the NPSG, the N:P ratio of remineralization (11 ± 2.2) was independent of the N:P of added organic material (5-23). This uniformity of inorganic ratios implies differential lability and N:P composition of residual semi-labile and refractory organic matter. Formation of refractory C and N rich organic matter, often termed the microbial pump, is a significant pathway for the transport and sequestration of elements in the aphotic zone of the ocean interior. The experimental results reported here suggest that differential supply of POM leads to rapid and preferential P remineralization, N:P remineralization independent of the N:P of added substrates, and variable N:P of residual organic matter. These findings help constrain our knowledge of elemental cycling in the marine environment. / Graduation date: 2013

Como em qualquer outra organização, as empresas de engenharia química vêm cada vez mais utilizando ferramentas de Tomadas de Decisão para escolhas de soluções técnicas para projetos, operações, desenvolvimento, dentre tantas. A tomada de decisão é o processo de responder a um problema, utilizando um conjunto de técnicas qualitativas e quantitativas para selecionar a solução ou ação, dentre várias alternativas que seja mais adequada para a resolução daquele problema. Dentre estas ferramentas, as mais utilizadas são a MAUT, do inglês Multiattribute Utility Theory (Teoria de Utilidade Multiatributos) e a AHP, do inglês Analytic Hierarchy Process (Processo de Análise Hierárquica).Neste trabalho, estes dois métodos são aplicados num mesmo problema de engenharia química: a seleção de um sistema para tratamento de compostos orgânicos voláteis durante o carregamento de navios que transportam petróleo e derivados. Para isto é realizada, em primeiro lugar, a descrição detalhada de cada método, a conceituação de composto orgânico volátil, a legislação pertinente e a descrição de cada alternativa como solução para controle deste tipo de emissão. Os resultados apontados pelos métodos MAUT e AHP são então comparados a fim de verificar se ambos conduzem a mesma solução. Pretende-se também observar o grau de influencia das diferentes áreas de atuação de uma organização na escolha final da tomada de decisão e verificar as percepções dos profissionais sobre cada método aplicado. Percebeu-se, entretanto, que as metodologias não conduziram, neste trabalho, a soluções idênticas, devido à influência das características de cada método, e que profissionais de uma mesma área de atuação tendem a tomarem o mesmo tipo de decisão

Como em qualquer outra organização, as empresas de engenharia química vêm cada vez mais utilizando ferramentas de Tomadas de Decisão para escolhas de soluções técnicas para projetos, operações, desenvolvimento, dentre tantas. A tomada de decisão é o processo de responder a um problema, utilizando um conjunto de técnicas qualitativas e quantitativas para selecionar a solução ou ação, dentre várias alternativas que seja mais adequada para a resolução daquele problema. Dentre estas ferramentas, as mais utilizadas são a MAUT, do inglês Multiattribute Utility Theory (Teoria de Utilidade Multiatributos) e a AHP, do inglês Analytic Hierarchy Process (Processo de Análise Hierárquica).Neste trabalho, estes dois métodos são aplicados num mesmo problema de engenharia química: a seleção de um sistema para tratamento de compostos orgânicos voláteis durante o carregamento de navios que transportam petróleo e derivados. Para isto é realizada, em primeiro lugar, a descrição detalhada de cada método, a conceituação de composto orgânico volátil, a legislação pertinente e a descrição de cada alternativa como solução para controle deste tipo de emissão. Os resultados apontados pelos métodos MAUT e AHP são então comparados a fim de verificar se ambos conduzem a mesma solução. Pretende-se também observar o grau de influencia das diferentes áreas de atuação de uma organização na escolha final da tomada de decisão e verificar as percepções dos profissionais sobre cada método aplicado. Percebeu-se, entretanto, que as metodologias não conduziram, neste trabalho, a soluções idênticas, devido à influência das características de cada método, e que profissionais de uma mesma área de atuação tendem a tomarem o mesmo tipo de decisão

Submitted by (lucia.rodrigues@ufrpe.br) on 2016-08-17T12:15:41Z No. of bitstreams: 1 Marcio Flequisson Alves Miranda.pdf: 1217281 bytes, checksum: bd45c2f7f20927f1da595dfd05965a6a (MD5) / Made available in DSpace on 2016-08-17T12:15:42Z (GMT). No. of bitstreams: 1 Marcio Flequisson Alves Miranda.pdf: 1217281 bytes, checksum: bd45c2f7f20927f1da595dfd05965a6a (MD5) Previous issue date: 2013-02-20 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / In Northeastern Brazil, in recent decades, with the increase of irrigation using in irrigated perimeters, often with inadequate management to local conditions, the soil salinization and sodification processes have intensified, promoting degradation and abandonment of large areas previously productive. Thus, we carried out a field survey to investigate the soil degradation in irrigated perimeter situated in the municipality of Custodia, semiarid region in Pernambuco, Brazil. Firstly were identified areas with degraded soils by salts excess, and also was done the experiment assembly with the intent to recover those areas through the application of organic and chemicals compounds, besides the technique of phytoremediation with Atriplex nummularia. For that, soil samples were taken in all 55 plots that make up the perimeter in the 0-10, 10-30 and 30-60 cm layers for the soils physical and chemical characterization, and chemical analyzes of the water used on the perimeter during periods of July/2009, January/2010, July/2010 and January/2011. After the selection of the degraded area into the irrigated perimeter, was mounted an experiment to recover the degraded soil by the evaluation of the treatments: 1) planting of Atriplex nummularia Lindl, 2) application of bovine manure, 3) sheep manure, 4) polymer, 5) gypsum and 6) control (witness). Four samples were taken, the first being at the same time of the experiment assembly (October 2009). After that, three more samples were taken, at six (April 2010), twelve (October 2010) and eighteen months (April 2011) after experiment assembly. Soil samples were collected at 0-10, 10-30 and 30-60 cm depth for the chemical analyzes. To evaluate the physical properties, soil samples were collected in the first (October 2009) and in the last (April 2011) collection at 0-10 and 10-30 cm layers. Were monitored the soil attributes in relation to treatment application with respect to time. The soils of the irrigated perimeter from Custódia are in the process of degradation and need to have their properties monitored over time to prevent its development. Among the cations evaluated, soluble and exchangeable Na+ was what was in higher concentrations, followed by the Cl- and by the RAS variable, besides increasing the PST in depth. The phytoremediation technique was effective in improving the soils quality and the application of sheep manure and polyacrylamide based polymer also acted positively in improving the quality of soil chemistry and physics. / Na Região Nordeste do Brasil, nas últimas décadas, com o incremento da irrigação em perímetros irrigados, muitas vezes com manejo inadequado às condições locais, os processos de salinização e sodificação de solos têm se intensificado, promovendo a degradação e abandono de extensas áreas anteriormente produtivas. Assim, realizou-se o levantamento da situação de degradação do Perímetro Irrigado de Custódia, no Sertão de Pernambuco, onde foram identificadas áreas com problemas de excesso de sais, seguindo-se de montagem de experimento para recuperação de uma dessas áreas, através da aplicação de compostos orgânicos e químicos, além da técnica da fitorremediação com Atriplex nummularia. Para isso, foram realizadas amostragens de solos em todos os 55 lotes que compõem o perímetro nas profundidades de 0-10, 10-30 e 30-60 cm para a caracterização física e química dos solos, além das análises químicas das águas utilizadas no perímetro nos períodos de Julho/2009, Janeiro/2010, Julho/2010 e Janeiro/2011. Após seleção de área degradada do perímetro, foi montado experimento de recuperação do solo testando-se os tratamentos: 1) plantio de Atriplex nummularia Lindl, 2) aplicação de esterco bovino, 3) esterco ovino, 4) polímero, 5) gesso e 6) controle (testemunha). Foram realizadas quatro amostragens, sendo a primeira no momento da montagem do experimento (Outubro de 2009), aos seis (Abril de 2010), aos doze (Outubro de 2010) e aos dezoito meses (Abril de 2011). As amostras de solo foram coletadas nas camadas de 0-10, 10-30 e 30-60 cm de profundidade para realização das análises químicas. Para a realização das análises físicas do solo coletaram-se amostras de solo na primeira coleta (Outubro de 2009) e na ultima (Abril de 2011) nas profundidades de 0-10 cm e 10-30 cm. Foram monitorados os atributos do solo com a aplicação dos tratamentos em função do tempo. Os solos do Perímetro Irrigado de Custódia encontram-se em processo de degradação e precisam ter suas propriedades monitoradas ao longo do tempo para evitar sua evolução. Entre os cátions avaliados, o Na+ solúvel e trocável foi o que esteve em concentrações mais elevadas, seguido pelo Cl- e pela variável RAS, além do aumento da PST em profundidade. A técnica da fitorremediação foi efetiva na melhoria da qualidade dos solos estudados e a aplicação do esterco ovino e do polímero a base de poliacrilamida também atuaram positivamente na melhoria da qualidade química e física do solo.

A quantificação de 11 compostos carbonílicos (formaldeído, acetaldeído, acetona, acroleína, propionaldeído, crotonaldeído, butiraldeído, benzaldeído, isovaleraldeído, valeraldeído e 2,5-dimetilbenzaldeído) e a identificação de outros 43 compostos orgânicos voláteis (alcanos, alcenos, aromáticos, halogenados e nitrogenados) foram feitas em 9 ambientes diferentes de trabalho localizados em áreas internas do Hospital Universitário, USP, São Paulo. Dentre os compostos carbonílicos, os mais abundantes em ordem decrescente foram formaldeído, acetona, acetaldeído e acroleína. As maiores razões de mistura de formaldeído foram observadas nas salas de Macroscopia (169,9 e 90,2 ppbv) e Técnicas Histológicas (11,7 e 58,7 ppbv), em decorrência da atividade desenvolvida nos locais. Na sala de Macroscopia, os níveis de formaldeído encontrados foram acima do limite (100 ppbv) estabelecido por órgãos internacionais que controlam a qualidade do ar em ambientes internos não industriais. As razões de mistura entre o ambiente interno e o ambiente externo, razões I/E, permitiram indicar a predominância dos compostos carbonílicos nos ambientes internos. A acroleína foi encontrada na faixa de 6,4 a 9,3 ppbv nos ambientes internos estudados. Na área externa, entretanto, foram encontrados valores similares (6,4 e 6,8 ppbv) aos dos ambientes internos obtendo razões I/E próximas de 1. Os compostos podem ter sido emitidos por materiais de construção e acabamento, fumaça do tabaco, adesivos, via metabolismo microbiano e bacteriano ou podem ter sido transportados por correntes de ar do ambiente externo para o ambiente interno / The quantification of 11 carbonyl compounds (formaldehyde, acetaldehyde, acrolein, acetone, propionaldehyde, crotonaldehyde, butiraldehyde, benzaldehyde, isovaleraldehyde, valeraldehyde and 2,5-dimethylbenzaldehyde) and the identification of another 43 volatile organic compounds (alkanes, alkenes, aromatic, halogenated and nitrogenated compounds) have been done with samples of 9 different indoor places inside the University Hospital at USP in São Paulo. Among the carbonyl compounds, there where found higher quantities of formaldehyde, acetone, acetaldehyde and acrolein in this order. The highest ratios of formaldehyde mixture have been observed at the Macroscopic room (169.88 and 90.2 ppbv) and Histological Techniques (11.7 and 58.7 ppbv), due to the routine activities of these places. At the Macroscopy room, the level of formaldehyde identified (100 ppbv) was above the international limits established to non-industrial internal places. The ratios of the mixture of indoor and outdoor places, I/O, indicate the biggest presence of carbonyl compounds in internal places. Acrolein has been identified (6.4 to 9.3 ppbv) at indoor places. At the external area, there where found similar values (6,4 to 6,8 ppbv), and the ratio I/O obtained is near to 1. The origin of these compounds is possibly construction materials, smoke of cigarettes, adhesives, metabolism of microorganisms or they may have come from the outdoor to the indoor

Abstract The work in this thesis concentrates on finding more active and durable catalysts for the demanding environmental application of the oxidation of sulfur-containing volatile organic compounds (S-VOCs). This application is challenging due to the high purification levels required and the catalyst deactivating nature of sulfur. In this thesis, dimethyldisulfide (DMDS) was used as the model molecule to represent S-VOCs since it is often present in odorous emissions and it is more difficult to treat than most of the other S-VOCs. It was found that the addition of a very small amount of Pt (0.3%) especially improves the selectivity of copper oxide based catalysts towards complete oxidation products ((carbon dioixide (CO2), water (H2O) and sulfur dioxide (SO2)) in DMDS oxidation. Catalyst characterization by transmission electron microscopy, temperature programmed reduction and X-ray photoelectron spectroscopy analyses suggests that this promoting effect is most likely due to the close interaction between Cu and Pt species on the bimetallic PtCu/&#947;-Al2O3 catalyst. The drawback of using the Al2O3 support is that it is not resistant towards sulfur poisoning. The deactivation of the self-made catalysts was studied with the help of an accelerated ageing procedure that was developed based on the information from the industrially aged volatile organic compound (VOC) catalysts. Industrial deactivation was caused by the sintering of the support and active metals and by the formation of metal sulfates with the support. After accelerated ageing, the silica doped alumina (Al2O3)0.8(SiO2)0.2 supported catalyst, showed remarkably promising results in terms of stability towards sulfur poisoning and the activity in DMDS oxidation was very close to that of the most active PtCu/Al2O3. The addition of less than 20% of SiO2 on the Al2O3 support led to a catalyst that is more selective and resistant to sulfur poisoning. / Tiivistelmä Väitöskirjassa tuotetaan uutta tietoa rikkipitoisten orgaanisten yhdisteiden (S-VOC) hapetukseen soveltuvien uusien katalyyttisten materiaalien synteesistä ja karakterisoinnista. S-VOC-yhdisteiden käsittely on vaativa katalyyttisen polton sovellus, koska näiden päästöjen käsittely edellyttää korkeaa puhdistustehoa, ja lisäksi yhdisteiden sisältämä rikki on katalyyttimyrkky. Tässä väitöskirjassa valittiin S-VOC-yhdisteitä edustavaksi malliaineeksi dimetyylisulfidi (DMDS), koska se on usein mukana käsiteltävissä S-VOC-päästöissä ja sen käsittely on vaativampaa kuin useiden muiden S-VOC-yhdisteiden käsittely. Tutkimustulosten mukaan hyvin pieni Pt-lisäys (0.3 %) parantaa erityisesti kuparioksidikatalyyttien selektiivisyyttä DMDS:n kokonaishapetustuotteiksi (CO2, H2O, SO2). Katalyyttien karakterisoinnin (läpäisyelektronimikroskopia, lämpötilaohjattu pelkistysreaktio, röntgensädefotoelektronispektroskopia) perusteella voidaan esittää parannuksen syyksi kuparin ja platinan läheinen kontakti bimetallisen PtCu/&#947;-Al2O3-katalyytin pinnalla. Al2O3-tukiaineen heikkoutena on sen deaktivoitumisherkkyys rikkiyhdisteiden läsnä ollessa. Väitöskirjatyössä valmistettujen katalyyttien deaktivitumista tutkittiin laboratoriomittakaavassa nopeutettujen ikäytyskokeiden avulla, jotka kehitettiin teollisessa käytössä deaktivoituneen katalyytin karakterisointien avulla saadun tiedon perusteella. Teollisessa käytössä olleen katalyytin deaktivoitumisen syyksi havaittiin tukiaineen ja aktiivisten metallien sintrautuminen sekä metallisulfidien muodostuminen tukiaineen kanssa. Nopeutettujen ikäytyskokeiden tulosten perusteella havaittiin, että piidioksidin lisäys alumiinioksiditukiaineeseen paransi tukiaineen rikin kestoa merkittävästi. Tutkimuksissa havaittiin myös, että piidioksidilla muokatun katalyytin aktiivisuus oli hyvin lähellä vastaavaa PtCu/&#947;-Al2O3-katalyytin aktiivisuutta. DMDS:n hapetuksessa selektiivisempi ja stabiilimpi katalyytti voidaan aikaansaada alle 20 %:n SiO2-lisäyksellä Al2O3-tukiaineeseen.

Ce manuscrit s’intéresse à une filière globale et durable de dépollution des eaux souterraines. Le polluant cible, le tétrachloroéthylène, est un composé organique volatil. La première étape de cette filière est la séparation du contaminant de l’eau. Elle a été réalisée par adsorption sur charbons actifs dans une colonne en lit fixe. Les résultats obtenus en laboratoire sur les capacités et les cinétiques d’adsorption ont permis de montrer l’efficacité de ce procédé. Un modèle issu de ces expériences a représenté correctement des conditions opératoires variées correspondant à celles utilisées dans l’industrie. Ce modèle a été validé par un pilote préindustriel installé sur site et fonctionnant en conditions réelles. La gestion des charbons actifs chargés en polluant a été étudiée. La régénération thermique a été privilégiée. Cette opération présente l’intérêt de rétablir les capacités d’adsorption des carbones activés et de récupérer les polluants en phase liquide. Bien que préférable à la production d’adsorbants, elle pourrait encore être plus durable et compétitive économiquement en effectuant le traitement thermique par voie solaire. Il a été montré que le taux de régénération est le même pour les régénérations solaire et classique. Il est donc possible, dans le cas du tétrachloroéthylène, de remplacer une source d’énergie fossile par le soleil. La solution de distillat obtenue lors de la régénération peut être minéralisée par photocatalyse hétérogène. Cette opération a été réalisée en laboratoire avec une lampe reproduisant le spectre solaire. La faisabilité de la photocatalyse solaire sur le résidu issu de cette filière de dépollution a ainsi été montrée. / This manuscript focuses on a comprehensive and durable treatment of polluted groundwater. The target contaminant, tetrachlorethylene, is a volatile organic compound. The first step in the treatment is the separation of contaminants. It was carried out by adsorption on activated carbons in a fixed bed column. The results obtained in the laboratory on the adsorption capacity and kinetics have shown the efficiency of this process. A mathematic model represented properly the various operating conditions corresponding to those used in the industry. This model has been validated by a pre-industrial pilot installed onsite and operating in real conditions. Management of spent activated carbons was studied. The thermal regeneration was chosen because it has the interest to restore the adsorption capacity of adsorbents and to collect the pollutants in a liquid phase. Although preferable to the production of activated carbons, it could still be economically more competitive and more sustainable by performing the heat treatment by solar means. It has been shown that the regeneration rate is the same for the solar and classical regenerations. It is therefore possible, in the case of tetrachlorethylene, to replace a fossil energy source by the sun.The distillate solution obtained during the regeneration can be mineralized by heterogeneous photocatalysis. This operation was carried out in the laboratory with a lamp reproducing the solar spectrum. The feasibility of solar photocatalysis on the final residue of the water treatment has been shown.

Les aérosols organiques secondaires (AOS) représentent une fraction significative de l'aérosol fin, et contribuent donc fortement à leurs impacts sur la santé, l'environnement et le climat. Connaitre les sources, l’évolution et les propriétés des AOS constitue actuellement un véritable enjeu pour la communauté scientifique. Ces AOS sont formés par condensation sur des aérosols préexistants des espèces de faible volatilité produites au cours de l’oxydation progressive de la matière organique gazeuse. L'objectif de ce travail de thèse vise à évaluer nos connaissances sur les processus de formation de l’AOS. La méthodologie mise en place consiste à (i) représenter les processus dans un modèle déterministe et explicite, (ii) confronter le modèle à des expériences de formation d’AOS effectuées dans des environnements contrôlés et (iii) examiner la sensibilité des évolutions simulées aux paramètres peu contraints. Le modèle GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere) développé au LISA permet de générer des schémas chimiques explicites sur la base de principes fondamentaux et de renseigner les grandeurs cinétiques et thermodynamiques associées. Sa capacité à représenter la formation des AOS a été évaluée par comparaison avec des expériences en chambres de simulation atmosphérique (CSA). Les comparaisons modèle/mesures des rendements finaux en AOS montrent que l’outil GECKO-A restitue correctement l’influence de la structure moléculaire sur la formation d’AOS. Cependant l’analyse quantitative montre que ces rendements sont systématiquement surestimés. Ceci suggère que des processus sont manquants ou mal représentés dans le modèle, en particulier la perte de composés organiques gazeux aux parois des CSA. L’intégration de ce processus dans le modèle conduit à (i) une diminution des rendements finaux simulés pouvant atteindre un facteur 2, (ii) une modification de la composition de l’AOS avec une sensibilité importante pour les espèces de premières générations (nitrates, hydroxynitrates et carbonylesters) et (iii) une vitesse de production de l’AOS plus faible lorsque la vitesse de transfert vers les parois augmente. La dynamique de formation des AOS n'est cependant pas correctement reproduite par le modèle. Les résultats montrent que les incertitudes sur les paramètres d’accommodation à la surface des particules et de pertes gazeuses aux parois permettent d’encadrer les données expérimentales. Aucune configuration unique de ces deux paramètres ne permet, toutefois, de représenter l’ensemble des expériences / Secondary organic aerosols (SOAs) represent a large fraction of fine particle matter, and contribute therefore to their impacts on human health, environment and climate. Understanding the sources, the evolution and the properties of SOAs is a challenge for the scientific community. These SOAs are produced by condensation onto preexisting aerosols of low volatility compounds formed during the progressive oxidation of gaseous organic matter. The objective of this thesis is to assess our knowledge of SOA formation processes. The methodology aims at (i) representing the processes in a deterministic and explicit model, (ii) comparing the modeling results with SOA measurements performed in controlled environments and (iii) examining the sensitivity of simulated results to poorly constrained parameters. The GECKO-A model (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere) developed at LISA generates explicit chemical schemes on the basis of fundamental principles and provides the related kinetic and thermodynamic constants. Its ability to represent SOA formation was evaluated by comparisons with experiments performed in environmental chambers. The comparisons between modeled and measured final SOA yields show that the GECKO-A tool accurately reproduces the influence of molecular structure on the SOA formation. However, quantitative analysis shows that these yields are systematically overestimated. This suggests that processes are missing or misrepresented in the model, in particular the loss of gaseous organic compounds on the chamber walls. The implementation of this process into the model leads to (i) a decrease of the simulated final yields up to a factor 2, (ii) a change on SOA composition with a high sensitivity for the first generation species (nitrates, hydroxynitrates and carbonylesters) and (iii) a decrease in the SOA production rate when the mass transfer rate to the wall is increased. The model fails however to reproduce the dynamic of SOA formation. The results show that the uncertainties on particle surface accommodation and wall losses allow to encompass the experimental data. However, no unique configuration of these two parameters can be selected for all of the experiments

Diploma thesis deals with the assessment of volatile organic compounds contamination of selected working environment in Gumotex, joint stock company using passive sampling. The theoretical part contains description of these compounds and their reactions in the atmosphere, practical use of these substances and their effect on human health. The possibilities of passive sampling and determination of these substances are described as well. The experimental part contains analysis of volatile organic compounds at two selected workplaces in Gumotex, joint stock company using passive samplers Radiello. Final determination by gas chromatography with flame ionization detector was preceded by adsorption surface extraction of sampler with carbon disulfide. In conclusion, obtained data are compared with the permissible exposure limits and maximum allowable concentrations, which are defined by the National Health Institute.

Les batteries à électrolyte circulant ou redox flow batteries (RFB) représentent une technologie prometteuse pour répondre aux besoins grandissants de stockage d'énergie. Elles seraient particulièrement adaptées aux réseaux électriques qui comptent une part grandissante d'énergie d'origine renouvelable, produite en intermittence. L'objet de ce travail est l'étude d'un nouveau type de RFB, actuellement développé par l'entreprise Kemiwatt. Il repose sur l'utilisation de molécules organiques, qui sont abondantes et recyclables. Le but de cette étude est d'améliorer la compréhension fondamentale de la batterie grâce à l'utilisation d'outils d'analyse précis et innovants. Chaque composant du système a d'abord été analysé via des moyens expérimentaux ex-situ. Les deux électrolytes composant la batterie ont ensuite été étudiés séparément en conditions réelles de circulation dans une cellule symétrique. Couplées à un modèle d'électrode volumique, les données ont été analysées pour identifier les facteurs limitants de chaque solution. La batterie entière a ensuite été étudiée dans un dispositif segmenté, permettant l'accès à la distribution interne du courant. Une étude paramétrique, réalisée avec la cellule segmentée a permis d'observer les effets du courant, du débit et de la température sur le fonctionnement de la cellule, puis d'établir une cartographie des conditions de fonctionnement idéales, suivant la puissance et l'état de charge de la batterie. L'aspect hydrodynamique du système a finalement été abordé en développant un modèle fluidique ainsi qu'une maquette expérimentale de cellule transparente pour visualiser l'écoulement. / Redox Flow Batteries (RFBs) are a promising solution for large-scale and low-cost energy storage necessary to foster the use of intermittent renewable sources. This work investigates a novel RFB chemistry under development at the company Kemiwatt. Based on abundant organic/organo-metallic compounds, this new technology promises the deployment of sustainable and long-lived systems. The study undertakes the building of a thorough knowledge base of the system by developing innovative reliable analytical tools. The investigation started from the evaluation of the main factors influencing the battery performance, which could be conducted ex-situ on each material composing the cell. The two electrolytes were then examined independently under representative operating conditions, by building a symmetric flow cell. Cycling coupled with EIS measurements were performed in this set-up and then analyzed with a porous electrode model. This combined modeling-experimental approach revealed unlike limiting processes in each electrolyte along with precautions to take in the subsequent steps (such as membrane pretreatment and electrolyte protection from light). A segmented cell was built and validated to extend the study to the full cell system. It provided a mapping of the internal currents, which showed high irregularity during cycling. A thorough parameter study could be conducted with the segmented platform, by varying successively the current density, the flow rate, and the temperature. The outcome of this set of experiments would be the construction of an operational map that guides the flow rate adjustment, depending on the power load and the state of charge of the battery. This strategy of flow rate optimization showed promising outcomes at the lab-cell level. It can be easily adapted to real-size systems. Ultimately, an overview of the hydrodynamic behavior at the industrial-cell level was completed by developing a hydraulic modeling and a clear cell as an efficient diagnostic tool.