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1
Balster, Jörg Henning. « Membrane module and process development for monopolar and bipolar membrane electrodialysis ». Enschede : University of Twente [Host], 2006. http://doc.utwente.nl/57595.
2
Xia, Jiabing [Verfasser], et Ulrich [Akademischer Betreuer] Nieken. « Reverse electrodialysis with bipolar membranes (REDBP) as an energy storage system / Jiabing Xia ; Betreuer : Ulrich Nieken ». Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2018. http://d-nb.info/1175951293/34.
3
Lundblad, Helena. « Split of sodium and sulfur in a Kraft mill and internal production of sulfuric acid and sodium hydroxide ». Thesis, KTH, Skolan för kemivetenskap (CHE), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-158486.
Résumé :
The removal of lignin in a Kraft pulp mill, with the aim to utilize the lignin as more value added green product than just firing lignin in black liquor, is possible with a LignoBoost plant. The LignoBoost plant uses sulfuric acid in the process and this results in an increased net input of sulfur to the pulp mills recovery cycle. The sodium/sulfur balance in a Kraft pulp mill is an important factor to be able to run a mill optimal. The increased input of sulfur into the mill when implementing a LignoBoost plant is therefore an issue to address. A too high sulfur/sodium ratio in the Kraft pulp mill is often solved by purging electrostatic precipitator dust from the recovery boiler. The major component of the ESP dust is sodium sulfate. When purging ESP dust from the recovery boiler the mill loose sodium and the need of sodium make-up increases. A large extent of the ESP dust that is not purged is returned to the recovery cycle of the mill via the evaporation plant. If the recycled sodium sulfate could be split and returned to the recovery cycle as one controlled sodium- and one controlled sulfur component or at least split into two flows where sulfur is enriched in one flow and sodium in the other flow, the sodium/sulfur balance would be easier controlled. In this master thesis the split of sodium and sulfur in sodium sulfate is addressed. The aim is to study opportunities to: • Enrich sodium and sulfur in two flows from the dissolved ESP dust, which is normally recycled to the evaporation plant. • Produce one sulfur component and one sodium component that can be utilized in the Kraft pulp mill, especially in an integrated LignoBoost process. • Accomplish this by using an electrochemical split of the sodium sulfate from the ESP dust to generate sodium hydroxide and sulfuric acid. To be able to produce one sulfur component and one sodium component from the dissolved ESP dust an electrodialysis with or without bipolar membranes is the method to use decided after contact with Eka Chemicals research and development department and literature studies. An electrodialysis cell produces sodium hydroxide and sulfuric acid, from the sodium sulfate solution, that can be used in the Kraft pulp mill. The difficulty by using an electrochemical cell with ion selective membranes is the need of a pure feed to the cell. If a high content of contaminations, such as multivalent ions, is present in the feed solution to the cell scaling can be formed. Scaling leads to shorter membrane life that result in higher operational cost for the cell stack. Due to the multivalent ions in the electrostatic dust a pre-treatment such as carbonate- and hydroxide precipitation removal of the ions is suggested, which results in a decrease of the multivalent ions in the feed solution. In previous work concerning electrochemical split of sodium sulfate the lack of utilization for the produced acid became negative in an economical point of view. The need of sulfuric acid to the LignoBoost plant is an advantage for the economical study. In this master thesis is: • An economical case study for the implementation of an electrochemical cell, electrodialysis with or without a bipolar membrane, in a Kraft pulp mill performed. • A sensitivity analysis performed and evaluated in the aim of addressing the change in payback time due to alternating: Sodium price Membrane life Utilization of the acid produced from the electrochemical cell. The economical case study concerns a Kraft pulp mill with a LignoBoost plant. Utilization of the acid to the LignoBoost- and tall oil plant is varied, as is the membrane life for the cell stack. The membrane life is varied due to the difficulty of predicting the ESP-feed solutions affect on the membranes. The feed solution has to be tested in a cell to decide the real life for the membrane in this case. The electrodialysis cell with bipolar membranes indicates promising economical gain for future implementation in a mill with LignoBoost lignin removal compared to the electrodialysis cell that indicates no economical gain for future implementation in a mill. For a mill with both a LignoBoost plant and a tall oil plant, i.e. optimized utilization of acid from the electrodialysis with bipolar membrane, and a five years membrane life in the cell, a payback of one and a half year can be reached. The same case but for an electrodialysis results in nine and a half payback years. The sensitivity analysis show that compared to the electrodialysis with bipolar membrane, the electrodialysis cell is more vulnerable to changes for the acid utilization, sodium hydroxide price and membrane life. The BME cell is most affected by changes in the sodium hydroxide price and the ED cell affects most by changes in the membrane life.
4
Abou-Diab, Mira. « Production éco-circulaire de peptides antibactériens, antifongiques et antioxydants déminéralisés à partir d'hémoglobine bovine par électrodialyse avec membranes bipolaires : étude de faisabilité, mécanisme enzymatique, optimisation des paramètres, comparaison avec l'hydrolyse conventionnelle et prévention du colmatage ». Electronic Thesis or Diss., Université de Lille (2018-2021), 2021. http://www.theses.fr/2021LILUR031.
Résumé :
Le cruor bovin, déchet des abattoirs est produit en très grande quantité dans le monde. Ce coproduit est composé principalement d'hémoglobine, une protéine riche en peptides bioactifs après son hydrolyse enzymatique. Cependant, lors de l'hydrolyse conventionnelle par la pepsine, des agents chimiques sont nécessaires pour ajuster et réguler le pH de la solution et, les hydrolysats finaux produits contiennent des niveaux élevés en sels minéraux. Pour pallier ces inconvénients, il a été proposé d'appliquer dans cette étude, pour la première fois, une technologie verte, appelée électrodialyse avec membrane bipolaire (EDMB), comme méthode alternative à l'hydrolyse enzymatique conventionnelle de l'hémoglobine afin d’obtenir des peptides bioactifs purifiés. Les objectifs de cette thèse étaient de tester la faisabilité de ce nouveau procédé pour la production de peptides bioactifs à partir d'hémoglobine bovine, d'établir les conditions optimales, d'éviter le colmatage membranaire et d'appliquer un nouveau procédé original d’EDMB à « multiple-étapes » permettant la production de peptides bioactifs déminéralisés sans ajout de produits chimiques. Des configurations bipolaires/monopolaires (anioniques ou cationiques) utilisant les ions H+ et OH- générés par les membranes bipolaires pour réguler le pH ont été étudiées et comparées à un procédé conventionnel utilisant des acides et des bases chimiques. La configuration d’EDMB formée avec les membranes cationiques a permis la production d'hydrolysats contenant une faible concentration en sels minéraux mais avec la présence d’un colmatage sur la membrane cationique, alors que la configuration d’EDMB utilisant des membranes anioniques a permis la production d'hydrolysats sans colmatage mais avec une concentration en sel similaire à celle de l’hydrolyse conventionnelle (contrôle). En se basant sur ces résultats, une nouvelle configuration d’EDMB à 3 compartiments a été mise en place et étudiée pour dénaturer l'hémoglobine, inactiver la réaction enzymatique et déminéraliser à 85% l'hydrolysat peptidique en simultané. Cependant, un colmatage a encore été observé sur la membrane anionique en raison de la précipitation de l'hème. Pour cette raison, une étape supplémentaire de décoloration a été réalisée avant la déminéralisation pour éviter le colmatage en utilisant l'acide électro-généré. Les peptides décolorés et déminéralisés récupérés ont montré une activité antioxydante, une activité antibactérienne contre plusieurs souches bactériennes (Gram + et Gram -) et pour la première fois une activité antifongique contre de nombreuses souches de moisissures et de levures. Dans un contexte d’économie circulaire, cette technologie durable s'avèrerait efficace pour effectuer plusieurs opérations simultanément et présente un potentiel important au niveau industriel pour l'hydrolyse du sang, puisqu'elle produit des bio-peptides purifiés ayant une faible teneur en sels minéraux et pouvant être utilisés comme conservateurs naturels sur la viandeBovine cruor, a slaughterhouse waste, is produced in large quantities all around the world. This co-product was mainly composed of hemoglobin, a protein rich in bioactive peptides after its enzymatic hydrolysis. However, during conventional hydrolysis, chemical agents are necessary to adjust/regulate the pH of the solution and the final hydrolysates produced contain high levels of mineral salts. Therefore, in this study, it is proposed to apply, for the first time, a green technology, named electrodialysis with bipolar membrane (EDBM), as an alternative method to the conventional enzymatic hydrolysis of hemoglobin to obtain purified bioactive peptides. The main objectives of the present thesis were to test the feasibility of this new process to produce bioactive peptides from bovine hemoglobin, to establish the optimal conditions, to avoid membrane fouling and to apply a new original « multiple-step » EDMB process allowing the production of demineralized bioactive peptides without the addition of chemical salts. Bipolar/monopolar (anionic or cationic) configurations using the H+ and OH- generated by the bipolar membranes to regulate the pH were investigated and compared to a conventional process using chemical acid and base. The EDBM configuration formed with cationic membranes allowed the production of hydrolysates containing a low concentration of mineral salts but with fouling formation on the cationic membrane, while EDBM configuration formed with anionic membranes allowed the production of hydrolysates without fouling but with a similar salt concentration than the control. Based on these results, a new 3 compartments EDBM configuration was carried-out for denaturing the hemoglobin, inactivating the enzymatic reaction and demineralizing up to 85% the hemoglobin hydrolysate simultaneously. However, a fouling was still observed on the anionic membrane due to hem precipitation. For this reason, an additional step of discoloration was tested before the demineralization to avoid fouling using the electrogenerated acid. The discolored and demineralized peptides recovered showed antioxidant activity, antibacterial activity against many bacterial strains (Gram + and Gram -) and for the first time antifungal activity against many molds and yeasts strains. Moving towards a circular economy, this sustainable technology has found to be effective in performing multiple operations simultaneously and has a great potential for industrial hydrolysis of blood, since it produces purified biopeptides with a low mineral content and can be used as natural preservatives on meat
5
Lu, Wei. « Étude de l'échange d'ions modulé électriquement : application du couplage échange d'ions-électrodialyse à la séparation de biomolécules ». Thesis, Vandoeuvre-les-Nancy, INPL, 2010. http://www.theses.fr/2010INPL027N/document.
Résumé :
Le présent travail vise à étudier le couplage de l’échange d’ions et de l’électrodialyse. Cette étude est appliquée à la séparation de biomolécules. Un des objectifs est de diminuer la génération d’effluents salins produits par les étapes d’échange d’ions utilisées de façon classique dans les bioséparations. Une première approche a conduit à la conception d’une architecture avec un mode de fonctionnement cyclique en 3 étapes qui permet de purifier certaines familles de peptides sans utiliser de tampon de pH ni générer d’effluents. Le dispositif expérimental est constitué d’une cellule d’électrodialyse dans laquelle sont introduites des résines échangeuses d’anions. Les trois étapes sont les suivantes : fixation des biomolécules sur la résine initialement sous forme carbonate, élution par une solution de dioxyde de carbone dissous dans l’eau, électrorégénération de la résine sous sa forme initiale, conduisant simultanément à la régénération de la solution d’acide carbonique. L’étape d’électrorégénération a été modélisée et les simulations permettent d’améliorer la compréhension des processus couplés mis en jeu comme les équilibres d’échange d’ions, les équilibres en solution, l’électromigration. Une deuxième approche a ensuite consisté à étudier les possibilités de contrôle du pH par voie électrochimique, afin de limiter l’utilisation de solutions tampons. La dissociation de l’eau, conduisant à la formation de protons et d’ions hydroxyles, a été plus particulièrement étudiée en mettant à profit les propriétés des contacts dits « bipolaires » sous l’effet d’un champ électrique. Il s’est alors avéré que les choix du type de résine et de la densité de courant permettent de jouer sur le pH Toutefois ce travail doit être poursuivi par la recherche d’architectures et de modes opératoires qui permettent d’obtenir un pouvoir tampon adéquatThe present work aims to study the coupling of ion exchange and electrodialysis. This study is applied to the separation of biomolecules. One objective is to reduce the generation of saline wastewater produced by the ion exchange steps used conventionally in bioseparations. One approach has led to the design of architecture with a cyclic mode in 3 steps to purify some families of peptides without using a buffer pH or generate wastes. The experimental device consists of an electrodialysis cell in which are introduced anion exchange resins. The three steps are: loading of biomolecules on the resin initially in the carbonate form, elution with a solution of carbon dioxide dissolved in water, electroregeneration of the resin in its original form leading simultaneously to the regeneration of the carbonic acid solution. Using a modelling of the electroregeneration step, simulations can improve the understanding of coupled processes as the ion exchange equilibria, the equilibria in solution, the electromigration. A second approach has then been to study the possibilities of controlling the pH by electrochemical means to limit the use of buffers. The dissociation of water, leading to the formation of protons and hydroxyl ions, has been particularly studied by accounting the properties of contacts called « bipolar » as a result of an electric field. It was established that the choice of resin type and the current density can modify the pH. However this work must be pursued through research of architectures and operating procedures that deliver appropriate buffer capacity
6
CULCASI, Andrea. « ELECTRICAL ENERGY STORAGE DEVICES BASED ON pH AND SALINITY GRADIENTS : MODELLING, EXPERIMENTS AND PILOTING ». Doctoral thesis, Università degli Studi di Palermo, 2021. http://hdl.handle.net/10447/478993.
7
Davis, Jake Ryan. « Production of Expendable Reagents from Raw Waters and Industrial Wastes ». Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/344216.
Résumé :
A couple of processes for electrosynthetic production of expendable reagents, namely acids, bases, and oxidants, from the native salt content of raw waters and industrial wastes were investigated, and the composition of mixed acids and bases made of sodium sulfate or sodium chloride salts were predicted using a model predicated on conservation principles, mass action relations, and Pitzer equations. Electrodialysis with bipolar membranes (BMED) was used to produce acids and bases in a single pass. Product concentration was limited only by the salt content of the feed water. The current efficiency for acid production was slightly higher than that for base, but neither dropped below 75%. Acid and base current utilization showed the same trends with respect to feed salt content and flow velocity, with higher efficiency at higher feed salt concentrations and flow velocities. Operating the BMED stack near the limiting current density of the bipolar membrane (BLCD) or above the limiting current density of the diluate compartment (LCD) decreased current efficiency and increased electrical power dissipation. Electrodialytic acid and base production was approximately10 times cheaper than the chemicals' f.o.b. unit costs as quoted on Alibaba.com. The mechanism and cost of on site peroxodisulfuric acid production by electrolysis of sulfuric acid solutions with boron doped diamond film anodes was investigated experimentally and with molecular dynamics (MD) and density functional theory (DFT) simulations. The cost of on site peroxodisulfate production was approximately 4 times less expensive than purchasing a 25 lb bag. It was shown that direct discharge of sulfate species produces sulfate radicals, which subsequently combined to form peroxodisulfuric acid. The likely hood of these reactions was dependent on electrode surface condition. Sulfate radicals could also be produced in solution by reaction with hydroxyl radicals generated by water discharge.
8
Jaouadi, Meyssa. « Étude d'un procédé hybride de séparation couplant l’électrodialyse à membrane bipolaire et l’échange d'ions : application à la valorisation de solutions diluées d'acide organique ». Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0208/document.
Résumé :
Le présent travail est dédié à l’étude d’un procédé hybride couplant l’électrodialyse à membrane bipolaire et l’échange d’ions. Cette étude est appliquée au traitement de solutions diluées d’acide acétique. L’objectif est double : acquérir une compréhension théorique des processus de transfert et des mécanismes qui impactent la consommation énergétique de ce système hybride et, de façon plus appliquée, proposer une configuration de cellule qui permette d’éliminer l’acide de la solution traitée en la transférant vers un compartiment de concentration. Cette configuration doit permettre d’obtenir le taux de purification le plus élevé possible tout en minimisant la consommation d’énergie. Des critères visant à optimiser le choix des résines échangeuses d’ions (fortes ou faibles) dans les compartiments de dilution sont proposés. L’intérêt de l’utilisation d’une résine cationique forte sous forme H+ dans le compartiment de concentration est par ailleurs mise en évidence, conduisant à une diminution de la résistance du compartiment et de ce fait de la consommation d’énergie. Une étude réalisée sur des systèmes « couplés » et « découplés » a permis d’identifier les contributions résistives des différents éléments de l’empilement. Cette approche a conduit à la détermination des paramètres d’un modèle qui permet de prévoir la résistance électrique d’un lit de résine dans une solution donnée. Les consommations spécifiques d’énergie (kWh/kg d’acide transféré) ont été évaluées en fonction du taux de purification souhaité. L’ensemble de l’étude a permis d’établir des recommandations pour la conception de la cellule et pour le choix des paramètres opératoiresThis work is dedicated to the study of a hybrid separation process involving bipolar membrane electrodialysis and ion exchange. This study is applied to the treatment of diluted effluents. The aim is first to acquire a theoretical understanding of transfer processes and mechanisms that affect energy consumption of this hybrid system. Then, in a more applied way, the objective is to be able to propose a cell configuration that allows to remove the acid from the treated solution by transferring it to a concentration compartment. This configuration must allow to obtain the highest purification rates as possible while minimizing energy consumption. Criteria aiming at optimizing ion exchange resins (strong or weak) in dilution compartment are proposed. The interest of the introduction of strong cationic resin under H+ form in the concentrated compartment is highlighted, as it enables reducing compartment resistance and hence energy consumption. Furthermore, experimental measurements successively conducted with “decoupled” and “coupled” systems identified resistive contributions of the different elements of the stack. This approach led to the determination of parameters of a model which predicts the resin bed electrical resistance in a given solution. Specific energy consumption (kWh/Kg transferred acid) was evaluated as a function of the desired purification rate. All the work led to recommendations for the cell design and for the choice of operating parameters
9
Schab, Frédéric. « Étude comparative des procédés d'électrodialyse et d'électrodéionisation : application à la fabrication d'acide lactique ». Thesis, Vandoeuvre-les-Nancy, INPL, 2007. http://www.theses.fr/2007INPL035N/document.
Résumé :
Le présent travail porte sur l’étude comparative des procédés d’électrodialyse et d’électrodéionisation. Les possibilités d’application des procédés électro-membranaires à la production d’acide lactique par voie fermentaire sont investiguées. Deux axes de recherche sont choisis : le premier consiste à extraire de manière continue le lactate de sodium hors du milieu de fermentation. Pour cela, un empilement d’électrodialyse ne comportant que des membranes anioniques est couplé au fermenteur : environ 95 % des ions lactate sont extraits lors de l’opération. Par comparaison avec une fermentation témoin en mode batch, aucune inhibition de la fermentation n’est observée, et la productivité est multipliée par 13. Le deuxième axe de recherche consiste à convertir le lactate de sodium en acide lactique : un taux de purification comparable à celui obtenu en échange d’ions est recherché. Un procédé continu d’électrodéionisation à membranes bipolaires permettant d’atteindre 99,9 % de taux de conversion est élaboré pour le traitement de produit dilué. Est présentée finalement la modélisation mathématique d’un compartiment d’électodéionisation : les points expérimentaux sont fortement similaires aux points recalculésThis work deals with the comparative study of electrodialysis and electrodeionization. The possibilities to integrate the electro-membrane processes in the lactic acid fermentive production lines are investigated. Two main research ways are chosen : the first one lies in the continuous extraction of natrium lactate out of the fermentation middle. For this, an electrodialysis stack of only anionic membranes is coupled with the fermenter : approximately 95 % of lactate are removed during the operation. By comparison with a standard fermentation in batch mode, no inhibition is observed, and the productivity is increased by 13. The second way is to convert the natrium lactate in lactic acid : a high purity rate is seeked. A continuous electrodeioniation process including bipolar membranes, leading to 99,9% conversion rate, is elaborated for the treatment of diluted solutions. Finally is presented the mathematic calculation of an electrodeionization compartment : experimental points and calculated values are very similar
10
Gabrielsson, Erik O. « Monopolar and Bipolar Membranes in Organic Bioelectronic Devices ». Doctoral thesis, Linköpings universitet, Fysik och elektroteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-110406.
Résumé :
In the 1970s it was discovered that organic polymers, a class of materials otherwise best know as insulating plastics, could be made electronically conductive. As an alternative to silicon semiconductors, organic polymers offer many novel features, characteristics, and opportunities, such as producing electronics at low costs using printing techniques, using organic chemistry to tune optical and electronic properties, and mechanical flexibility. The conducting organic polymers have been used in a vast array of devices, exemplified by organic transistors, light-emitting diodes, and solar cells. Due to their softness, biocompatibility, and combined electronic and ionic transport, organic electronic materials are also well suited as the active material in bioelectronic applications, a scientific and engineering area in which electronics interface with biology. The coupling of ions and electrons is especially interesting, as ions serve as signal carriers in all living organisms, thus offering a direct translation of electronic and ionic signals. To further enable complex control of ionic fluxes, organic electronic materials can be integrated with various ionic components, such as ion-conducting diodes and transistors. This thesis reports a background to the field of organic bioelectronic and ionic devices, and also presents the integration of ionic functions into organic bioelectronic devices. First, an electrophoretic drug delivery device is presented, capable of delivering ions at high spatiotemporal resolution. The device, called the organic electronic ion pump, is used to electronically control amyloid-like aggregation kinetics and morphology of peptides, and offers an interesting method for studying amyloids in vitro. Second, various ion-conducting diodes based on bipolar membranes are described. These diodes show high rectification ratio, i.e. conduct ions better for positive than for negative applied voltage. Simple ion diode based circuits, such as an AND gate and a full-wave rectifier, are also reported. The AND gate is intended as an addressable pH pixel to regulate for example amyloid aggregation, while the full-wave rectifier decouples the electrochemical capacity of an electrode from the amount of ionic charge it can generate. Third, an ion transistor, also based on bipolar membranes, is presented. This transistor can amplify and control ionic currents, and is suitable for building complex ionic logic circuits. Together, these results provide a basic toolbox of ionic components that is suitable for building more complex and/or implantable organic bioelectronic devices.
11
Hong, Jin Gi. « Development of process-based model and novel nanocomposite cation exchange membranes for salinity gradient power production ». Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53530.
Résumé :
Ocean salinity is a renewable energy source that has not been recognized and could provide an opportunity to capture significant amount of clean energy when it mixes with river water. One of the processes emerging as a sustainable method for capturing energy from seawater is reverse electrodialysis (RED), which generates power via the transport of the positive and negative ions in the water through selective ion exchange membranes (IEMs). RED power generation is relatively close to commercialization, but its application is often limited by system power efficiency in natural water conditions. Although various types of salt ions exist in environmental saline water, most efforts have been focused on sodium chloride as a single ionic source in the water and the effects of other common multivalent ions (e.g., magnesium and sulfate) on power generation remain unexplored. Moreover, the commercial feasibility of RED is highly challenged by the absence of specialized RED membranes. Currently available IEMs are not optimized for RED power conversion systems, but successful operation is highly dependent on the membranes used. Major advances in manufacturing of proper IEMs will be a critical pathway to accelerate large-scale energy conversion by RED.
Therefore, this study aimed at advancing our understanding of the RED power system for efficient and stable salinity gradient energy generation. Specifically, it is comprised of three parts. First, a mathematical model is developed for three different monovalent and multivalent ion combinations to determine the effect of different ionic compositions of the feed solution on the power density. Efforts are further made to optimize the RED system with respect to improving power density by investigating the sensitivity of key response parameters such as flow rate ratios and intermembrane distance ratios. Second, novel organic-inorganic nanocomposite cation exchange membranes (CEMs) are synthesized for RED application by introducing functionalized inorganic materials into an organic polymer matrix. The effect of inorganic particle filler loading within the organic polymer matrix on physico- and electrochemical performance is investigated. The results revealed that the increase of functionalized nanoparticle loading controls the effective ion transport in the membrane structure and there exists an optimum amount of nanoparticles (i.e., charged groups), which performs the best in selectively exchanging counter-ions, while excluding co-ionic species. Third, the membrane structure modification is demonstrated to enhance ion transport while maintaining large surface-charged functional groups in the polymer matrix. We have synthesized custom nanocomposite CEMs to tailor porous membrane structures of various thicknesses, aging (evaporation) time, and inorganic nanoparticle loadings. We have further tailored the membrane structure by incorporating different inorganic particle filler sizes. These engineered design approaches are found to be highly effective in obtaining desired physico- and electrochemical properties, which allowed higher ionic current flow throughout the system. Furthermore, for the first time we showed the successful application of tailor-made nanocomposite CEMs in a RED stack and achieved superb power density, which exceeds the power output obtained with the commercially available membranes.
In summary, this dissertation has advanced our understanding of salinity gradient energy generation using RED technique. Specifically, computational modeling and simulation study investigates the development and optimization approaches of the RED process for practical application of RED using natural water conditions. Furthermore, the RED membranes developed in this dissertation focuses on fabrication, characterization, and optimization of cation exchange membranes. Overall, the results of this study are anticipated to benefit the future optimization of energy-capturing mechanisms in RED and provide the better pathway for the sustainable salinity gradient power generation.
12
Willson, Terrence R. « Synthesis of ion exchange membranes for reverse electrodialysis via radiation induced graft co-polymerisation ». Thesis, University of Surrey, 2018. http://epubs.surrey.ac.uk/846392/.
Résumé :
A major disadvantage of fossil fuels being the primary source of global energy is the negative effect that the burning of such fuels has on the planet. This is evident in factors including climate change. Reverse electrodialysis (RED) is an emerging membrane-based process for clean energy conversion. The technique works by utilising the transport of cations and anions through ion-exchange membranes (IEMs) to create an electrical current, via differences in chemical potential, when mixing salt solutions of different concentrations. The core components of a RED cell, and the largest factor affecting the performance and economic viability, are the IEMs. Recently, increased efforts have been made with regard to the preparation of IEMs and understanding the relationships between membrane properties and RED cell power performance. The work in this thesis has focused on the development of RED-focused IEMs by radiation induced grafting polymerisation (RIG). The RIG technique has been used to chemically modify commercially available polymer films to produce a large sample of IEMs targeted for application in RED. The IEM properties were experimentally determined and used as part of a literature recognised mathematical model to estimate the gross power densities that can theoretically be obtained by each IEM in a working RED cell. The results obtained for RIG IEMs contradicts the earlier notion that IEM permselectivity is of less significance than area resistance and indicate that a minimum permselectivity (≈ 90%) is required for RED IEMs. A trade-off relationship between the two properties is observed, rationalised by Donnan exclusion factors surrounding IEM water content. Chemical crosslinking was implemented into RIG methods to control excessive gravimetric water uptake (WU%). Linear tertiary diamine head-groups were used to produce crosslinked anion-exchange membranes (AEMs), with tetramethylhexanediamine (TMHDA) head-group yielding theoretical gross power densities of 3.42 W m-2 for single IEM RED model calculations and 1.89 W m-2 for AEM/CEM pair calculations (paired with literature SPEEK 65 CEM). Crosslinked CEMs were produced via chemical crosslinking by divinylbenzene (DVB) and bis(vinylphenyl)ethane (BVPE) was implemented into the RIG method, which resulted in cation-exchange membranes (CEMs) yielding theoretical gross power densities of 5.55 and 5.99 W m-2 respectively, for single IEM RED model calculations and 2.81 and 2.71 W m-2 for AEM/CEM pair calculations (paired with commercial Neospeta® AFN AEM).
13
Jesus, Juliana Mendonça Silva de. « Estudo do envelhecimento de membranas trocadoras de íons em contato com soluções sintéticas à base de HEDP ». Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-05092017-105121/.
Résumé :
O uso do cianeto em processos de eletrodeposição proporciona à prática industrial risco ambiental e ocupacional. Com isso, estudos têm buscado alternativas para a substituição desse agente nocivo. O Instituto de Pesquisas Tecnológicas (IPT) desenvolveu um banho de cobre alcalino sem cianeto, que utilizou como substituinte o HEDP (1-hidroxietano-1,1-difosfônico). Para a recuperação desse ácido a eletrodiálise foi avaliada, que consiste no uso de um sistema de membranas trocadoras de íons (MTI) e de corrente elétrica como força motriz. Meios oxidantes, corrosivos e com materiais orgânicos favorecem a degradação da membrana, inibindo sua capacidade em separação. Alternativas de manutenção têm sido estudadas para o aumento da vida útil das membranas, como o uso de agentes de limpeza. O estudo do envelhecimento proporciona a avaliação de um material em condições específicas, a fim de monitorar alterações em função do tempo de contato com o meio. O presente estudo propõe o envelhecimento de membranas aniônicas comerciais em soluções diluídas, provenientes do banho sintético de cobre à base de HEDP. Como objeto de estudo, foram selecionadas duas membranas, sendo uma heterogênea e uma membrana homogênea. Essas foram envelhecidas em três concentrações distintas (CuHEDP 1%, 5%, 10% v/v), por 400h de contato, sob agitação. As possíveis modificações estruturais foram avaliadas por meio de técnicas como a microscopia eletrônica de varredura acoplada à espectroscopia de energia dispersiva de raios-X (MEV-EDS), a análise termogravimétrica (TGA) e espectroscopia por infravermelho com transformada de Fourier (FTIR-ATR). As propriedades intrínsecas das membranas estão diretamente relacionadas ao seu caráter seletivo e morfológico. Para avaliar tais propriedades, foram utilizados ensaios cronopotenciométricos e a titulação potenciométrica. As propriedades investigadas foram o grau de inchamento, a capacidade de troca, a resistência elétrica, a densidade de corrente limite e a permeseletividade. Paralelamente, submeteu-se a membrana heterogênea ao envelhecimento em um sistema de eletrodiálise por 400h, monitorando-se as alterações em sua densidade de corrente e resistência elétrica a cada 100h de ensaio. Em adição, realizou-se a avaliação de agentes de limpeza de caráter ácido e básico, em concentrações distintas. O agente que atingiu melhor desempenho em remover a incorporação iônica foi aplicado às membranas envelhecidas em 100h de envelhecimento. Em seguida, essas foram reavaliadas a partir de ensaios eletroquímicos. Observou-se que houve interação entre os íons em solução e as membranas estudadas, que proporcionaram alterações em sua estrutura e propriedades, porém sem causar modificações que indicassem o descarte para ambas membranas.The use of cyanide in electrodeposition processes provides industrial practice environmental and occupational risk. Thereby, studies have looked for alternatives for the substitution of this noxious agent. The Institute of Technological Research (ITR) developed an alkaline copper bath cyanide-free, which used HEDP (1-hydroxyethane- 1,1-diphosphonic) as a substitute. For the recovery of this acid the electrodialysis was evaluated, which consists of the use of an ion-exchange membrane (IEM) system and electric current as the driving force. Oxidizing, corrosive and organic materials favor membrane degradation, inhibiting their separation ability. Maintenance alternatives have been studied to increase the shelf life of membranes, such as the use of cleaning agents. The ageing study provides the evaluation of a material under specific conditions, in order to monitor changes as a function of the time of contact with the medium. The present study proposes the ageing of commercial anionic membranes in dilute solutions from the synthetic copper bath with HEDP. The purpose of the study was selected two membranes, being a heterogeneous and homogeneous membrane. These were aged in three distinct concentrations (CuHEDP 1%, 5%, 10% v/v) for 400 hours of contact, under stirring. The possible structural modifications were evaluated by techniques such as scanning electron microscopy coupled to X-ray dispersive energy spectroscopy (SEM-EDS), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR-ATR). The intrinsic properties of the membranes are directly related to their selective and morphological character. To evaluate such properties, chronopotentiometric assays and potentiometric titration were used. The investigated properties were swelling degree, ion-exchange capacity, electrical resistance, current density, and permselectivity. In parallel, the heterogeneous membrane was subjected to ageing in an electrodialysis system for 400h, monitoring the changes in its current density and electrical resistance every 100h of the test. In addition, acid and basic cleaning agents were evaluated in different concentrations. The agent that achieved the best performance in removing the ionic incorporation was applied to the membranes aged in 100h of ageing. These were then reevaluated from electrochemical tests. It was observed that there was interaction between the ions in solution and the membranes studied, which provided alterations in its structure and properties, but without provide modifications that indicated the need of disposal for both membranes.
14
Nguyen, Duy Linh. « La technologie des membranes pour le traitement des eaux de surface dans le delta du Mékong ». Thesis, Montpellier, 2016. http://www.theses.fr/2016MONTT211/document.
Résumé :
L’accès à l’eau potable est un des plus importants problèmes que l’on rencontre partout dans le monde même dans les pays riches en eau. Par exemple, les provinces côtières du Delta du Mékong (DM) subissent des périodes alternées d’inondations et de sécheresse. De plus, le changement climatique à l’origine d’une diminution de la pluviométrie et d’intrusion d’eau salée affecte gravement la qualité des eaux de la région. Les principales sources de pollution proviennent des déchets humains et des rejets des élevages de poissons, bétail et volaille. La pollution aux pesticides peut s’avérer un problème sérieux dans certaines zones. La détérioration de la qualité des eaux dans le DM et l’absence d’accès à l’eau potable dans les communes rurales via des systèmes d’approvisionnement sûrs entraine une augmentation des maladies d’origine hydrique liées à la salinité, la présence de microorganismes et de polluants organiques. L’objectif de ce travail a consisté à examiner dans quelle mesure la technologie membranaire peut permettre de produire de l’eau potable de qualité. L’étude a porté sur les eaux saumâtres contenant des pesticides. Deux solutions modèles synthétiques ont été choisies pour représenter les eaux de surface du DM. Le dessalement et l’élimination des pesticides ont été réalisés en utilisant la nanofiltration (NF) couplée à l’électrodialyse. Le logiciel Nanoflux® a été utilisé pour interpréter les performances de deux membranes de NF (NF90 et NF270). Par ailleurs, la consommation d’énergie des deux procédés couplés a été estimée en fonction de la qualité de l’eau d’alimentation. Toutes ces données seront utilisées pour concevoir un démonstrateur pour la production familiale d’eau potableAccess to clean water is one of the most important problems that is encountered worldwide even in countries as water-rich. For instance, the Mekong Delta (MD)’s coastal provinces have to face up to alternated flooding and drought periods. Moreover, climate changes inducing less rainfall and salt water intrusion water severely affect the water quality of the area. The main sources of pollution come from the human and farming wastes including fish, livestock and poultry. Pesticide pollution can also be a serious problem in some areas. The deterioration of water quality in the MD and the lack of access to clean water via safe supply systems in the rural communes entail an increase of waterborne diseases related to the salinity, the presence of microorganism and organic pollutants. The study is aimed at investigating the membrane technology to treat surface water in the MD region in order to produce good drinking water. The study was focused on brackish waters containing pesticides. Two synthetic model water samples were chosen as representative of surface waters found in the Mekong Delta. Desalination and pollutant removal were performed using nanofiltration (NF) integrated with electrodialysis. The Nanoflux® software was used to explain the experimental performance of two NF membranes (NF90 and 270). On the other hand, energy consumption of the two coupled processes was also estimated depending on the quality of water feed. All the data obtained should be used in the future to design a demonstrator pilot for the family-sized production of drinking water
15
Strand, Robin Viktor. « Characterization of ion selective membranes for application in reverse electrodialysis systems : Concentration dependency of the apparent transport number ». Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-25836.
Résumé :
Revers elektrodialyse (RED) er en fornybar, ikke-forurensende måte å generereelektrisitet på ved å blande vann med forskjellige saltkonsentrasjoner, e.g.elvevann og sjøvann. RED er avhengig av ioneselektive membraner. Dereseffektivitet kan bli beskrevet med deres effektive transporttall, som er ratioenmellom den målbare elektromotoriske kraften (Emf) over membranen og detideelle potensialet, som er sett på som det teoretiske maksimum. Her er detvist at den ikke-ideelle oppførselen til en ioneselektiv membran, det at denhar et effektivt transporttall under 1 og at det effektive transportallet går nedmed økende saltkonsentrasjon, kan bli forklart med elektroosmose. Dette er ikontrast til den utbredte tolkningen at det effektive transporttallet er et målpå selektiviteten til membranen. Vanntransporttallet beskriver retningen oggraden av elektroosmose.Denne tolkningen er testet eksperimentelt med Emf målinger av ioneselektivemembraner ved forskjellige konsentrasjoner. Fra resultatene er det vistat den anionselektive membranen Fumasep FAD oppfører seg som om den erhelt selektiv og har et vanntransporttall på -4.8±0.8 med saltvannsløsningeri konsentrasjonsområdet 2-30 gram natriumklorid (NaCl) per liter. Derfor,hvis produsenter som Fumatech vil produsere mer effektive membranertrenger de ikke å gjøre membranene mer selektive ovenfor ioner, men istedenformå de gjøre dem mer selektive ovenfor vann. Det er også vist teoretiskat vanntransporten i spesielle tilfeller kan gi transporttall over 1. Dette kanbidra til å forklare resultatene som nylig ble publisert av Nature.Effekten av denne modellen av det effektive transporttallet på predikertytelse av RED systemer ble undersøkt ved hjelp av Matlab simulasjoner.Det ble sammenliknet med hvordan det effektive transporttallet vanligvis erbehandlet, det vil si som en konstant som beskriver selektiviteten av membranen.Det effektive transporttallet er regnet ut fra Emf målinger og avhengerav konsentrasjonen som blir brukt under denne målingen. Det ble funnet atden gamle metoden er en god approksimasjon ved høye strømningshastigheter,med under 1 % forskjell ved strømningshastigheter over 1 mm/s, hvis deteffektive transporttallet er målt i konsentrasjonene ved innløpet. Hvis transporttalleter målt ved andre konsentrasjoner vil forskjellen være større. Denpredikerte kraftproduksjonen vil være 7 % mindre hvis konsentrasjonene 20og 30 g/l NaCl er brukt istedenfor 3 og 30 g/l NaCl. I disse simulasjonene etvanntransporttall på 10 var brukt. Et større vanntransporttall vil gi størreiiieffekt. Vanntransporttallene til ioneselektive membraner har blitt m°alt til °avære 4-50, men de fleste kommersielle membranene har ikke vanntransporttalls°a høye som 20-50.
16
Manenda, Mahder Seifu. « Separation of bioactive peptides by electrodialysis with ultrafiltration membranes : membrane characteristics, ex-situ and in-situ digestion and their impact on peptide migration ». Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10410.
Résumé :
Dissertation presented to Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa for obtaining the master degree in Membrane EngineeringTrypsic hydrolysis of whey protein isolate was performed simultaneously with (in-situ) and before (ex-situ) fractionation by electrodialysis with ultrafiltration membrane (EDUF) to obtain bioactive peptides. Two ultrafiltration membrane (UFM) materials, PES and PVDF, were used for a 120 minute EDUF fractionation of the hydrolysate. The two membranes showed similar zeta potential measurements at the pH of operation, 7.8, but had significantly different conductivity which decreased significantly after use in EDUF. Peptide migration to anionic (A-RC) and cationic (C+RC) peptide recovery compartment was strongly dependent on the electrical conductivity of the UFMs than their types or the digestion strategy used. For UFMs with close values of conductivity, peptide migration to the A-RC was observed to be higher with in-situ digestion while peptide migration to the C+RC was higher in an ex-situ digestion. When the two membrane types, PES and PVDF, have closer values of conductivities, PVDF was observed to exhibit more migration than PES. Peptide migration to the C+RC varied from 16.56 ± 5.36 μg/mL to 103.10 ± 2.76 μg/mL for PVDF membrane with significantly different conductivities: 2.73 ± 0.32 mS/cm and 5.47 ± 0.56 mS/cm, respectively. Peptide migration to the A-RC varied from 4.41 ± 0.86 μg/mL to 49.65 ± 6.13 μg/ml for PVDF membrane with significantly different conductivities: 3.163 ± 0.12 mS/cm and 5.23 ± 0.04 mS/cm, respectively. HPLC-MS studies showed 23 major peaks that were generated on whey protein isolate digestion by trypsin. 9 of these peaks migrated to the A-RC while 3 migrated to the C+RC. Among the anionic peptides 3 peptides are known to have hypocholesterolemic effect, 1 is antibacterial and 1 is antihypertensive. Among the cationic peptides 1 is antihypertensive. EDUF appears to be a powerful new technique that can fractionate bioactive peptides in terms of mass and charge.
The EM3E Master is an Education Programme supported by the European Commission, the European Membrane Society (EMS), the European Membrane House (EMH), and a large international network of industrial companies, research centres and universities
17
Glabman, Shira. « Effect of inorganic filler size on nanocomposite ion exchange membranes for salinity gradient power generation ». Thesis, Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54311.
Résumé :
Reverse electrodialysis (RED) is a technique that can capture electrical potential from mixing two water streams of different salt concentration through permselective ion exchange membranes. Effective design of ion exchange membranes through structure optimization is critical to increase the feasibility of salinity gradient power production by RED. In this work, we present the preparation of organic-inorganic nanocomposite cation exchange membranes containing sulfonated polymer, poly (2,6-dimethyl-1,4-phenylene oxide), and sulfonated silica (SiO2-SO3H). The effect of silica filler size at various loading concentrations on membrane structures, electrochemical properties, and the RED power performance is investigated. The membranes containing bigger-sized fillers (70 nm) at 0.5 wt% SiO2-SO3H exhibited a relatively favorable electrochemical characteristic for power performance: an area resistance of 0.85 Ω cm2, which is around 9.3% lower than the resistance of the membranes with smaller filler particles. The power performance of this nanocomposite cation exchange membrane in a RED stack showed 10% higher power output compared with the membranes containing small particle size and achieved the highest gross power density of 1.3 W m-2. Thus, further optimized combination of material properties and membrane structure is a viable option for the development of effective ion exchange membrane design, which could provide desirable electrochemical performance and greater power production by RED.
18
Le, Xuan Tuan. « Contribution à l'étude électrochimique des propriétés de membranes échangeuses cationiques en milieu acide sulfurique ». Doctoral thesis, Universite Libre de Bruxelles, 2006. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210782.
19
Kadel, Sabita. « Impact of physicochemical properties of filtration membranes on peptide migration and selectivity during electrodialysis with filtration membranes : development of predictive statistical models and understanding of mechanisms involved ». Doctoral thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/66602.
Résumé :
Au cours du procédé d'électrodialyse avec membrane de filtration (EDMF), les peptides chargés migrent sélectivement à travers des membranes de filtration (MFs) dans les compartiments respectifs de récupération des peptides anioniques (ARC) ou cationiques (C+ RC). Par conséquent, le type d'interaction entre les peptides et l'interface de la MF, en raison de ses propriétés physicochimiques, doit avoir un impact significatif sur la performance globale de l’EDMF (migration et sélectivité des peptides). Donc, l'objectif principal de cette thèse de doctorat était d'étudier les propriétés physicochimiques principales des MFs qui contribuent aux interactions interfaciales peptide-membrane facilitant ou entravant la migration globale et la séparation sélective des peptides pendant l’EDMF, et de comprendre les mécanismes impliqués dans ces interactions. Ainsi, dans cette étude, 16 MFs, caractérisées en termes de propriétés physicochimiques (potentiel zêta, conductivité, nature hydrophile/hydrophobe de la surface et des pores, épaisseur, rugosité, porosité et pourcentage de distribution des macropores dans la couche filtrante), ont été testées lors de l'EDMF pour séparer simultanément les peptides anioniques et cationiques d'un hydrolysat de protéines de lactosérum complexe et bien caractérisé. Dans la première étude, 6 MFs, différentes en termes de matériau, ont été testées incluant une membrane d’ultrafiltration (polyéthersulfone (PES)) comme contrôle et cinq membranes de microfiltration (fluorure de polyvinylidène (PVDF) et chlorure de polyvinyle (PVC-silice, fonctionnalisée (sulfopropyle ou amine quaternaire) ou non)). Les analyses de redondance (RDA) et de régression multivariées ont démontré qu’au moins deux des quatre propriétés suivantes des MF avaient un impact significatif sur la migration de tout peptide chargé ; le potentiel zêta, l’hydrophilie de surface/des pores, la porosité et la rugosité. De plus, l'effet important de la taille des pores sur la sélectivité des peptides a également été rapportée dans cette étude. Enfin, des modèles statistiques prédictifs qui relient la migration des peptides avec les propriétés de MF significatives ont été proposés. Dans la deuxième étude, réalisée sur des membranes de PES avec une large gamme de seuils de coupure (MWCO) de (5 à 300 kDa), une relation linéaire a été observée entre le MWCO et la migration globale des peptides (MGP) pour les deux compartiments de récupération. iii Cependant, la migration sélective des peptides vers ARC ou C+ RC s'est révélée être influencée par le MWCO des MFs ainsi que par les propriétés physicochimiques (charge et poids moléculaire (PM)) des peptides ; la migration d'un peptide ayant un faible PM et une faible charge (positive ou négative) était favorisée lorsqu’une MF ayant un petit MWCO était utilisée, tandis que l’inverse se produisait pour un peptide ayant un PM élevé et une charge élevée. Dans la troisième étude, l'effet de la combinaison du matériau de la membrane (polyacrylonitrile (PAN), PES et PVDF) /MWCO (30 et 50 kDa) sur la migration et la sélectivité des peptides, a tout d’abord été étudié. Les effets simples du matériau membranaire et du MWCO sur la MGP vers C+ RC, de même que l'effet combiné des matériaux membranaires/MWCO sur la MGP vers ARC et la migration sélective des peptides vers les deux compartiments de récupération ont été observés. Deuxièmement, une RDA réalisée sur l’ensemble des données obtenues pour les MFs sélectives testées dans cette recherche doctorale, a démontré l'impact significatif du potentiel zêta, de la conductivité, de la rugosité et du pourcentage de distribution des macropores dans la couche filtrante des MFs sur la MGP. Concernant la migration sélective des peptides, en plus des propriétés des MFs susmentionnées, l'impact significatif de l'angle de contact a été démontré pour au moins la migration d’un peptide anionique et/ou cationique vers leurs compartiments de récupération respectifs. Ces propriétés significatives ont favorisé différentes interactions telles qu’électrostatique, exclusion de taille et hydrophile/hydrophobe entre l’interface de la MF et le peptide, ce qui a eu pour effet de, soit faciliter, soit inhiber la migration de ce peptide. Enfin, des modèles statistiques prédictifs globaux ont été développés pour la MGP et pour la migration de chaque peptide individuel vers ARC et/ou C+ RC en fonction des propriétés importantes de la MF utilisée. Ces modèles permettent ainsi l'estimation du comportement de migration de ces peptides lorsque les MFs, sur une large gamme de propriétés physicochimiques, sont utilisées en EDMF. Les résultats obtenus dans cette thèse ont démontré, pour la première fois, la corrélation significative entre les propriétés physicochimiques des MFs, et la migration et la sélectivité des peptides pendant l'EDMF. Cependant, les modèles prédictifs développés dans cette étude iv peuvent être utilisés pour la gamme de peptides et les propriétés physicochimiques des MFs testées. Par contre, les mécanismes et explications proposés dans cette étude, concernant les interactions MF/peptide, peuvent être généralisés afin de comprendre tous les types d'interactions peptide/membrane. Comme perspectives à ce travail, l’étude de différentes sources d'hydrolysats, d’autres MFs et d’un hydrolysat produit par d’autres enzymes permettra la validation de ces modèles statistiques et leur généralisation.During electrodialysis with filtration membranes (EDFM), charged peptides selectively migrate through filtration membranes (FMs) to their respective anionic (ARC) or cationic (C + RC) peptide recovery compartments. Consequently, the type of interactions occurring between FM and peptide at the interface, due to their physicochemical properties, must have significant impact on overall EDFM performances (peptide migration and selectivity). Therefore, the main objective of this doctoral thesis was to investigate the major FM properties that contribute to peptide-membrane interactions at the interface, which either facilitates or hinders global migration and selective separation of peptides during EDFM, and to understand the mechanisms involved behind those interactions. Thus, in this study, 16 FMs, characterized in terms of their physicochemical properties (zeta potential, conductivity, hydrophilic/hydrophobic nature of the surface and pores, thickness, roughness, porosity and percentage of macropores distribution in filtrating layer) were tested during EDFM to simultaneously separate anionic and cationic peptides from a well-characterized complex whey protein hydrolysate. In the first study, 6 FMs were tested, differing in terms of membrane materials, including one ultrafiltration (polyethersulfone (PES)) as a control and 5 microfiltration ( one polyvinylidene fluoride (PVDF) and four polyvinyl chloride (PVC)-silica: two functionalized (sulfonyl or amino) or two non-functionalized). Redundancy analysis (RDA) and multivariate regression analysis demonstrated that at least two FM properties among zeta potential, pore/surface hydrophilicity, porosity and roughness significantly impacted the migration of any charged peptide. In addition, the important effect of pore size on peptide selectivity was also reported. Finally, predictive statistical models that link each peptide migration with significant FM properties were proposed. In the second study, which was carried out on PES membranes with a wide range of molecular weight cut-offs (MWCOs) (5 kDa to 300 kDa), a linear relation was noticed between MWCO and global peptide migration (GPM) to both recovery compartments. However, the selective peptide migration to A - RC or C + RC was found to be influenced by the vi MWCO of FMs as well as physicochemical properties (charge and molecular weight (MW)) of peptides. For instance, the migration of a peptide having low MW and low charge (positive or negative) was favored when a FM with small MWCO was used, while the opposite was observed for a peptide having high MW and high charge. In the third study, the effect of combination of membrane material (PAN, PES and PVDF)/MWCO (30 and 50 kDa) on peptide migration and selectivity was first studied. The simple effect of membrane material and MWCO on GPM to C+ RC was observed, while the combined effect of membrane materials/MWCO on GPM to A - RC and selective peptide migration to both recovery compartments was observed. Secondly, a RDA was performed on the data obtained for all the selective FMs tested in this doctoral research, which demonstrated the significant impact of zeta potential, conductivity, roughness and percentage of macropores distribution in the filtrating layer of FMs on GPM. Concerning selective peptide migration, in addition to the aforementioned FM properties, the significant impact of contact angle was noticed for at least one anionic and/or cationic peptide migration to their respective recovery compartments. These significant FM properties were found to trigger different interactions such as electrostatic, size exclusion and hydrophilic/hydrophobic between FM and peptide at the interface resulting in either facilitation or inhibition of peptide migration. Finally, global predictive statistical models were developed for GPM and each individual peptide migration to ARC and/or C+ RC based on these significant FM properties, which allow the estimation of their migration behavior when FMs having a wide range of physicochemical properties are used during EDFM. The results obtained in this Ph.D. thesis demonstrated, for the first time, the significant correlation between physicochemical properties of FMs, and peptide migration and selectivity during EDFM. The predictive models developed in this study can be used for the range of peptides and FMs tested. Moreover, the types of interactions occurring between FMs and peptide at the interface, and mechanisms and explanations proposed in this study can be applied to understand all types of peptide/membrane interactions. Validation of such models vii by using different sources of hydrolysates or different FMs or a hydrolysate produced by other enzymes will be the main perspectives of this research work.
20
Proença, Marcela Pinheiro. « Desenvolvimento de membranas íon-seletivas com poliestireno sulfonado e polianilina dopada para a aplicação em eletrodiálise ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/18585.
Résumé :
Atualmente, a preocupação com a redução da poluição industrial tem motivado os pesquisadores na busca de novas tecnologias para o tratamento de resíduos industriais. Tecnologias limpas, como a eletrodiálise, são capazes de tratar alguns destes resíduos, como por exemplo o efluente da indústria de galvanoplastia, minimizando os impactos que ocorreriam caso eles fossem descartados diretamente no meio ambiente. O componente principal desta técnica é a membrana na qual ocorre a etapa de retirada dos íons da solução. Atualmente estas membranas são importadas e caras, o que justifica o desenvolvimento de membranas eficientes e acessíveis. Neste sentido, no presente trabalho membranas de poliestireno sulfonado/ poliestireno de alto impacto (SPS/HIPS), polianilina dopada com ácido canforsulfônico/ poliestireno sulfonado/ poliestireno de alto impacto (PAniCSA/SPS/HIPS), polianilina sulfonada/ poliestireno sulfonado/ poliestireno de alto impacto (SPAN/SPS/HIPS), e polianilina dopada com ácido p-tolueno sulfônico/ poliestireno sulfonado/ poliestireno de alto impacto (PAniTSA/SPS/HIPS) foram desenvolvidas usando o método de mistura química. As membranas foram caracterizadas utilizando as técnicas Análise termogravimétrica (TGA), Análise dinâmico Mecânica (DMA), e Microscopia Eletrônica de Varredura (MEV). Membranas foram submetidas a curvas corrente-potencial e ensaios de eletrodiálise em soluções de NaCl e KCl, a fim de determinar o transporte iônico através das mesmas. Os resultados foram comparados com uma membrana comercial Selemion CMT. A extração percentual média para íons de Na+ obtidos pelas membranas desenvolvidas foi superior a 20%.Nowadays the concern with the reduction of industrial pollution has motivated researchers to found out new technologies for treatment of industrial waste. The clean technologies, as electrodialysis, are capable of treating some these residues, as for example the galvanoplasty’s waste, minimizing the impacts that would happen to them if they were discarded directly on the environment. The main component of this technique is the membrane on which occurs the ions removal stage of the solution. The membranes are imported and expensive what justifies the development of efficient and accessible membranes. In this sense, in the present work membranes of sulfonated polystyrene / high impact polystyrene (SPS/HIPS), polyaniline doped with camphorsulfonic acid / sulfonated polystyrene / high impact polystyrene (PAniCSA/SPS/HIPS), sulfonated polyaniline/ sulfonated polystyrene / high impact polystyrene (SPAN/SPS/HIPS), and polyaniline doped with p-toluenesulfonic acid / sulfonated polystyrene / high impact polystyrene (PAniTSA/SPS/HIPS) were developed using chemical mixture method. Membranes were characterized by Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Dynamic Mechanical Analysis (DMA) and Scanning Electronic Microscopy (SEM). Membranes were submitted to current-voltage curves and electrodialysis experiments with NaCl and KCl solutions, in order to determine ionic transport through them. Results were compared with a commercial membrane, Selemion CMT. The average percent extraction for Na+ ions obtained by membranes developed were beyond 20%.
21
Garcia-Vasquez, Wendy. « Etude du comportement à long terme des membranes échangeuses d’ions utilisées dans les procédés d’électrodialyse ». Thesis, Paris Est, 2013. http://www.theses.fr/2013PEST1111/document.
Résumé :
Lors de ce travail de thèse nous avons étudié le comportement à long terme de différentes membranes échangeuses d'anions et membranes échangeuses de cations utilisées en électrodialyse conventionnelle pour l'industrie agroalimentaire. Certaines de ces membranes sont du type homogène et d'autres du type hétérogène. La méthodologie suivie tout au long de ce travail est basée sur la comparaison de nombreuses propriétés physico-chimiques, structurales et mécaniques d'échantillons neufs et d'autres vieillis dans un module d'électrodialyse industriel (in-situ) ou selon des protocoles que nous avons mis au point en laboratoire (ex-situ).L'étude du vieillissement in-situ des différentes membranes échangeuses d'ions utilisées dans le traitement des acides organiques et dans la déminéralisation du lactosérum nous a permis de confirmer que les membranes échangeuses d'anions sont beaucoup plus sensibles au vieillissement que les membranes échangeuses de cations. Par ailleurs, nous avons démontré que les changements dans les propriétés de transport, et donc dans les performances des membranes, dépendent en grande partie des modifications survenues sur leur microstructure. Nous avons apporté des améliorations au modèle micro-hétérogène pour permettre d'interpréter et de quantifier les conséquences du vieillissement des membranes échangeuses d'ions. L'effet des opérations de nettoyage sur le comportement à long terme des membranes échangeuse d'ions utilisées dans les opérations d'électrodialyse en agroalimentaire a fait l'objet de notre étude ex-situ. Ce vieillissement est effectué par des solutions acides, alcalines ou par cycles alternant les deux solutions, ou également par des solutions oxydantes de type eau de Javel. Nous avons démontré, entre autres, que les cycles de nettoyage acide-base effectués lors des opérations d'électrodialyse en agroalimentaire engendrent d'importantes dégradations sur les membranes échangeuses d'anions et que ce nettoyage est la cause essentielle du vieillissement des membranes échangeuses d'anions homogènes utilisées en électrodialyse pour la déminéralisation du lactosérum. Une confrontation entre les résultats obtenus par les vieillissements ex-situ et in-situ nous permet de confirmer leur similarité. Ainsi, nous pouvons proposer que, sous des conditions opératoires bien choisies, les études ex-situ sont bien adaptées pour la réalisation d'un vieillissement artificiel contrôléThe long term behavior of anion and cation-exchange membranes used in conventional electrodialysis for food industry applications was investigated. Some of these membranes were homogeneous and some others were heterogeneous. The approach of this thesis is based upon the analysis of several physico-chemical, structural and mechanical properties of new samples and aged ones in electrodialysis stacks (in-situ) or under artificial ageing protocols at laboratory scale (ex-situ).The in-situ investigation of different ion-exchange membranes used in the purification of organic acids and in whey demineralization confirmed that anion-exchange membranes are more prone to degradation than the cation-exchange membranes. It was observed, as well, that changes in the transport properties, and subsequently in the membrane performance, are dependant of the modifications of the membrane microstructure. The microheterogeneous model was improved and applied for the interpretation and quantification of the ageing consequences on ion-exchange membranes. Assessment of the cleaning process effect on the long term behavior of ion-exchange membranes used in electrodialysis for the food industry applications was the objective of the ex-situ investigation. The ageing protocols were performed using acidic or alkaline solutions or by alternating both of them, as well as in oxidant bleach solutions. Among other findings, it was proven that the damage caused by the acid-base cleaning cycles provoked severe degradation to anion-exchange membranes. Furthermore this cleaning process was the main cause of ageing of homogeneous anion-exchange membranes in electrodialysis for whey demineralization. Comparisons between results obtained by in-situ and ex-situ ageing protocols confirmed their similarity. Therefore, it may be considered that under well-chosen operation conditions, ex-situ investigation is a well adapted method for the artificial ageing
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Jiang, Di. « Synthesis of novel hybrid cation exchange membranes for reverse electrodialysis using sulfonated poly(vinyl alcohol) (sPVA)/ poly (2,6-dimethyl-1,4-phenylene oxide) (sPPO) ». Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54240.
Résumé :
Ion exchange membranes (IEMs) play an important role in a reverse electrodialysis (RED) system for salinity gradient power generation. Challenges exist in the selection of appropriate membrane materials in order to reduce the capital cost of membrane manufacturing and in the design of proper RED membranes to optimize the energy-producing process. This work presents the synthesis of hybrid cation exchange membranes by incorporating two well-known inexpensive organic polymers with great film-forming ability. Sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) (sPPO) polymer mixed with sulfated polyvinyl alcohol (sPVA) has been proved to have great potential as a candidate for RED membranes. The prepared membranes with 2 to 10 wt% sPVA have improved the permselectivity up to 87 % and reduced area resistance down to 1.31 ohm cm-2, which is comparable to the commercially available FKS (Fumasep®, Germany) membranes. The best performance was achieved with hybrid membrane containing 5 wt% of sPVA which resulted in a gross power density at 0.46 W/m2. This power density is 14% greater than that achieved using commercial FKS membranes. This study shows a great potential of using organic-organic hybrid membranes for the RED power generation system.
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Bdiri, Myriam. « Etude du décolmatage, par procédés chimiques et biologiques, des membranes échangeuses d'ions utilisées en électrodialyse dans le domaine agroalimentaire ». Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1070.
Résumé :
L’électrodialyse (ED) est principalement basée sur l’action spécifique des membranes échangeuses d’ions (MEIs) et est largement répandue en industrie agroalimentaire pour la stabilisation tartrique des vins, la désacidification et le traitement des jus de fruits, la déminéralisation du lactosérum ou l’élimination et le fractionnement des protéines du lait. Le colmatage organique, accentué par la complexité de composition des effluents alimentaires et leur richesse en composés phénoliques, représente un facteur majeur de limitation de l’efficacité des procédés et des performances des MEIs. Ce phénomène provoque une diminution de la sélectivité de membranes, une augmentation de leur résistance électrique et réduit le rendement énergétique du procédé conduisant à des pertes économiques en industrie. Cette étude consiste principalement à étudier le décolmatage de MEIs par procédés chimiques et biologiques. Des lots de membranes échangeuses de cations (MECs) et d’anions (MEAs) neuves (1 lot de MEC et 1 lot de MEA) et usées (3 lots de MECs et 2 lots de MEAs) à différentes durées d’utilisation en ED dans l’industrie agroalimentaire –application confidentielle- ont été étudiés. L’ensemble des échantillons ont préalablement été caractérisés pour détermination des paramètres physicochimiques (capacité d’échange (CE), épaisseur (Tm), conductivité électrique (km), angle de contact (θ), teneur en eau (WC) ainsi que la fraction volumique de la solution inter-gel (f2) résultant de l’exploitation du modèle microhétérogène), de structure et morphologiques par spectroscopie IR-TF, microscopie optique, microscopie électronique à balayage et mécaniques par essais de traction. Les effets directs et indirects (causés par les opérations de lavage régulières en industrie) du colmatage ainsi que l’anisotropie des propriétés mécaniques de membrane ont été mis en évidence. Des méthodes de nettoyage non agressives et respectueuses de l’environnement ont été expérimentées en mode statique en ex-situ : Solutions salines (NaCl à 35 g.L-1 et eau de mer reconstituée), solution hydro-alcoolique (mélange eau-éthanol 12%, pH=3,5) et solutions biologique utilisant 3 catégories d’agents enzymatiques (Rohalase BX-BXL, β-glucanase / Corolase 7089, endo-peptidase / Tyrosinase, polyphenol-oxydase) dont les conditions opératoires d’activité enzymatiques optimale ont été déterminées. L’évolution de CE, km, θ et f2 ont été suivis en fonction de la durée de nettoyage. Les solutions salines ont un effet négligeable sur le nettoyage en profondeur mais restent efficaces pour le nettoyage de surface. Cependant, l’application de la solution hydro-alcoolique et des solutions d’enzymes se sont avérées être efficaces pour le décolmatage interne et externe et parviennent à rétablir significativement les paramètres suivis. Il a été démontré que les composés phénoliques, principaux constituants des effluents traités, sont en majeure partie responsables du colmatage des MEIs. Ceux-ci forment des nanoparticules colloïdales denses, non perméables aux ions dans les méso- et macropores des MEIs et ne pénètrent pas dans ses micropores. Une modification du modèle microhétérogène selon cette hypothèse a permis de fournir une interprétation adéquate du km et de modéliser la modification structurale de la phase inter-gel engendrée par les mécanismes de colmatages de polyphénols et expliquer les raisons de diminution du facteur f2app. Une méthode d’extraction utilisant un mélange de solvants (25%V/V, acétone/méthanol/isopropanol/eau) a été mise au point et a permis d’extraire certains composés phénoliques de différents lots de MECs et MEAs usées et ont été identifiés par chromatographie liquide à haute performance. Il a été démontré que les interactions entre les composés phénoliques et la matrice polymère étaient principalement régies par l’empilement des cycles aromatiques et des interactions électrostatiques du type CH-pi et pi-pi ainsi que les liaisons hydrogènesConventional electrodialysis (ED) is mainly based on the specific action of ion exchange membranes (IEMs) and is widely used in food industry for tartaric stabilization of wines, deacidification and treatment of fruit juices, demineralization of whey or elimination and fractionation of milk proteins. The organic fouling, accentuated by the complex composition of the food effluents and their richness in phenolic compounds, represents a major limitative factor of the process efficiency and the IEMs performance. This phenomenon causes a decrease in the selectivity of membranes, an increase in their electrical resistance and reduces the energy efficiency of the process leading to economic losses in industry. This study mainly consists in studying the IEMs cleaning by chemical and biological methods. Two batches of new membranes (cation- (CEMs) and anion-exchange membranes (AEMs)) and five batches of used ones (3 CEMs and 2 AEM) with different durations of use in ED units in food industry -confidential application- have been studied. All the samples have been previously characterized to determine their physicochemical parameters (ion-exchange capacity (IEC), thickness (Tm), electrical conductivity (km), contact angle (θ), water content (WC) and the volume fraction of the inter-gel solution (f2) resulting from the study of the micro heterogeneous model), structure and morphology by FTIR spectroscopy, optical microscopy, scanning electron microscopy and mechanical by tensile strength tests. The direct and indirect effects (caused by the regular cleaning operations in industry) of fouling as well as the anisotropy of the membranes mechanical properties have been highlighted. Non-aggressive and environmentally friendly cleaning methods have been experimentally tested in ex-situ static mode: Saline solutions (35 g.L-1 NaCl and reconstituted seawater), hydro-alcoholic solution (12% water-ethanol mixture, pH = 3,5) and biological solutions using 3 categories of enzymatic agents (Rohalase BX-BXL, β-glucanase / Corolase 7089, endo-peptidase / Tyrosinase, polyphenol oxidase) whose operating conditions of optimal enzymatic activity have been determined. The evolution of IEC, km, θ and f2 were followed in function of the cleaning duration. Saline solutions have a negligible effect on intern cleaning but remain efficient for extern cleaning. However, the application of the hydro-alcoholic solution and enzyme solutions have been found to be efficient for both intern and extern cleaning and led to significant recoveries of the studied parameters. It has been shown that phenolic compounds, the principal constituents of treated effluents, are mainly responsible for MEIs fouling. Apparently, they form dense colloidal nanoparticles not permeable for ions within membrane meso- and macropores, not penetrating into micropores. A modification of the micro heterogeneous model under this assumption allowed an adequate interpretation of km and the modelization of structural modifications of the inter-gel phase generated by the fouling mechanisms by polyphenols and explained the reasons why the f2app decreases. An extraction method using a mixture of solvents (25% V/V, acetone/methanol/ isopropanol/water) was developed and made it possible to extract certain phenolic compounds from different batches of used CEMs and AEMs that were identified by high performance liquid chromatography. It has also been demonstrated that the interactions between the phenolic compounds and the polymer matrix are mainly governed by the stacking of aromatic rings and electrostatic interactions of the CH-pi and pi-pi type as well as the hydrogen bonds
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Babíková, Barbora. « Membránové separace ». Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2018. http://www.nusl.cz/ntk/nusl-376883.
Résumé :
This diploma thesis deals with the general characteristics of membrane processes and separations. It includes a chapter on the history of development of the technology industry using membranes as a medium for separating chemicals based on their specific properties and also the importance of such processes at present. This work then introduces the basic principles of mass transport by membranes and describes various types of membranes and materials used for their production. It also deals with electromembrane separations, including electrodialysis. The practical part focuses on experimental separation of solutions of four sodium salts by means of electrodialysis. Based on the electrical current and conductivity measurements of these solutions in time during membrane separation are evaluated process parameters such as efficiency, energy consumption, transferred electrical charge, and mass of the sodium salt.
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Andreeva, Marina. « Etude du colmatage des membranes échangeuses d'ions lors de l'électrodialyse de solutions de sels de Ca2+ et Mg2+ : influence des propriétés de surface ». Thesis, Paris Est, 2017. http://www.theses.fr/2017PESC1018/document.
Résumé :
Le colmatage à la surface et dans la masse d’une membrane échangeuse d’ions est un obstacle majeur à son utilisation en électrodialyse. En bloquant les voies conductrices d’ions à travers la membrane, le dépôt réduit la surface active de la membrane et conduit à une résistance au transfert de matière supplémentaire.Trois membranes échangeuses de cations ont été utilisées lors de ce travail: une membrane commerciale hétérogène MK-40 et deux de ses modifications (une membrane MK-40/Nafion obtenue par revêtement de la surface de MK-40 avec un film de Nafion® homogène conducteur d’ions, et une membrane MK-40/PANI obtenue par synthèse de polyaniline sur la surface de la MK-40). Les solutions utilisées sont des solutions de CaCl2 et MgCl2 aux concentrations 0,02 et 0,04 mol/L, ainsi qu’une solution modélisant la composition minérale du lait, concentrée 3 fois. La visualisation de la surface de la membrane est réalisée par microscopie optique et microscopie électronique à balayage. L’analyse élémentaire des dépôts sur la surface de la membrane est réalisée par l’analyse aux rayons X. Le caractère hydrophobe-hydrophile de la surface de la membrane est estimé par la mesure de l’angle de contact. La chronopotentiométrie et la voltamétrie ont été utilisées pour caractériser la vitesse de transport des cations à travers les membranes et la dissociation d’eau à la surface ; la mesure du pH de la solution dessalée a été effectuée en parallèle.Il est démontré que l’hydrophobicité relativement élevée de la surface de la membrane, son hétérogénéité électrique et géométrique créent les conditions favorables au développement de l’électroconvection. L’intensité de l’électroconvection par rapport à la membrane non modifiée est significativement plus élevée dans le cas de la MK-40/Nafion mais plus faible dans le cas de la MK-40/PANI. L’électroconvection provoque le mélange de la solution à la surface de la membrane dans une couche d’environ 10 µm d’épaisseur. Cet effet augmente de manière significative le transfert de matière en mode de courant intensif, empêche ou réduit le colmatage et réduit aussi le taux de dissociation de l’eau sur la surface de la membrane. L’intensité de l’électroconvection dépend essentiellement du degré d’hydratation du contre-ion ; elle augmente avec son rayon de Stokes. Le taux de croissance des dépôts minéraux Mg(OH)2, Ca(OH)2 et CaCO3 sur la surface de la membrane échangeuse d’ions est déterminé par la pente du chronopotentiogramme. On établit expérimentalement que, par rapport à la vitesse de colmatage sur la membrane MK-40 non modifiée, celle sur la surface de MK-40/Nafion devient plus petite mais celle sur la surface de la MK-40/PANI, devient plus grande.Le taux du colmatage est considérablement réduit lorsqu’un mode de courant électrique pulsé est appliqué. Un tel mode permet de réduire de moitié la différence de potentiel et d’atteindre un état quasi-stable du fait que le précipité devient instableScaling on the surface and in the bulk of ion-exchange membranes is a considerable locker for electrodialysis. The scale reduces the effective surface area of the membrane and leads to additional resistance to the mass transfer and solution flow.Three cation-exchange membranes are used in this study: a heterogeneous commercial MK-40 membrane and two of its modifications. The MK-40/Nafion membrane is obtained by mechanical coating the MK-40 membrane surface with a homogeneous ion-conductive Nafion® film. Modification of the MK-40/PANI membrane is carried out by polyaniline synthesis on the membrane surface. The solutions used in the study are 0.02 and 0.04 mol/L CaCl2 and MgCl2 solutions, as well as the solution, imitating the mineral composition of milk, concentrated 3 times. The visualization of the membrane surface is made using optical and scanning electron microscopy. The elemental analysis of the scale on the membrane surface is made by X-ray analysis. The hydrophobic-hydrophilic balance of the membrane surface is estimated by the contact angle measurements. To characterize the cation transport through and the water splitting rate, chronopotentiometry and voltammetry methods are used, pH measurement of the diluate solution is conducted at the same time.It is shown that the relatively high hydrophobicity of the membrane surface, its electrical and geometric heterogeneity, create conditions for the development of electroconvection. The electroconvection intensity in the case of MK-40/Nafion is significantly higher, and in the case of MK-40/PANI is lower in comparison with that of the unmodified membrane. Electroconvection vortexes cause the mixing of the solution at the membrane surface in a 10 µm thick layer. This effect significantly increases mass transfer in intensive current modes and prevents or reduces the scaling process, as well as reduces the water splitting rate at the membrane surface. The rate of electroconvection essentially depends on the counterion hydration degree, it increases with increasing the counterion Stokes radius. The rate of the scale formation on the membrane surface is determined by the slope of the chronopotentiogramme. The formation of Mg(OH)2, Ca(OH)2 and CaCO3 scales is observed. It is experimentally established that the scaling rate on the surface of MK-40/Nafion is smaller, and on the surface of the MK-40/PANI is larger in comparison with the MK-40 membrane. The scaling rate is significantly reduced when the pulsed electric current mode is applied. Such mode allows the reduction of the potential drop more than twice and achievement of a quasi steady-state because an unstable periodically crumbling scale occurs
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Valerdi, Pérez Ramón. « Caracterización, evaluación y optimización de una planta de desalación por electrodiálisis reversible ». Doctoral thesis, Universidad de Murcia, 1999. http://hdl.handle.net/10803/10848.
Résumé :
El objetivo de ésta tésis fue la caracterización y optimización de una planta piloto EDR IONICS Tipo Aquamite I, con dos etapas eléctricas y seis etapas hidráulicas, buscando las condiciones de funcionamiento para una máxima eficacia del dispositivo.
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Narang, Gurtej Singh. « Synthesis and Characterization of Novel Pol(arylene ethers) for Gas Separation and Water Desalination Membranes ». Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/95968.
Résumé :
This thesis focuses on the synthesis and characterization of various poly(arylene ether)s to improve the efficiency of gas separation and water desalination membranes. This class of polymers includes polymers such as poly(arylene ether sulfone), poly(arylene ether ketone) and poly(phenylene oxide) which offer excellent thermal and mechanical stability and usually have high enough rigidity to support gas separation and water desalination operations. Besides the plethora of properties offered by the homopolymers, these polymers can also be post-modified to cater to specific needs. For example, the polyphenylene oxides have been brominated to increase the permeability for gas separation applications. Blending is another viable method to impart desirable properties to polymers.
Bisphenol A based poly(arylene ether ketone) (BPAPAEK) has been blended with commercially available poly(2,6-dimethylphenylene oxide)s (PPO) of different molecular weights in a fixed ratio (66/34 wt/wt) and in various ratios of a 22000 g/mol PPO. All the blends were UV crosslinked to minimize plasticization by condensable gases and analyzed for gel fractions, whereas, only the 22,000 g/mol blends were tested for transport properties since they yielded the highest gel fractions and exhibited the best mechanical properties. The crosslinking reduced the free volume and improved the selectivity with some drop in permeability. The blends with 90% of the 22000 g/mol PPO by weight was plotted closest to the upperbound.
A phosphine oxide based poly(arylene ether ketone) (POPAEK) was blended with the various PPOs in a similar manner. The results were compared to the BPAPAEK based blends in terms of miscibility behavior and transport properties. It was found that the POPAEK based blends had higher permeability due to the higher fractional free volumes of the POPAEK. The POPAEK was more compatible with the PPOs than BPAPAEK as seen by analyzing various blend permeability models, mechanical properties and scanning electron microscope images. Moreover, blends with both the PAEKs displayed only a small drop in mechanical properties, such as the Young's modulus and the yield strength in comparison to the parent polymers.
Hydroquinone based poly(arylene ether sulfone) oligomers were synthesized, post-sulfonated and chemically crosslinked to determine the effect of water uptake, fixed charge concentration and block length of oligomers on the salt permeability and the hydrated mechanical properties of the networks. The sulfonic acid groups were placed strategically and quantitatively on the hydroquinone units. The strategic placement of the acid groups may help in maintaining high rejection of monovalent ions in the presence of divalent ions, as shown in unpublished work by our group. It was found that the water uptake and fixed charge density had the opposite effects on the salt permeability. Also, the salt permeability varied differently for 5000g/mol and 10000g/mol block based networks.
Another polymer that was investigated in this thesis was poly(2-ethyl-2-oxazoline) (PEtOx). An elaborate account of synthesis of monofunctional, heterobifunctional and telechelic poly(2-ethyl-2-oxazoline)s using different initiators including methyl triflate, activated alkyl halides (e.g., benzyl halides), and non-activated alkyl halides has been presented in this thesis. Endgroup functionalities and molecular weight distributions were studied by SEC, 1H NMR and titrations. The oligomers initiated with the benzyl or xylyl chloride had a PDI of 1.3-1.4 which is broader than expected for a living cationic ring opened polymer. This was attributed to the participation of covalent species which propagated slowly in the activated halide reactions. These oligomers were quantitatively terminated as proven by NMR and titrations. Due to the molecular weight distributions and quantitative termination these oligomers were deemed to be desirable for drug delivery applications.PHD
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Daryaei, Amin. « Synthesis and Characterization of Linear and Crosslinked Sulfonated Poly(arylene ether sulfone)s : Hydrocarbon-based Copolymers as Ion Conductive Membranes for Electrochemical Systems ». Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/86439.
Résumé :
Sulfonated poly(arylene ether sulfone)s as ion conductive copolymers have numerous potential applications. Membranes cast from these copolymers are desirable due to their good chemical and thermal stability, excellent mechanical strength, satisfactory conductivity, and excellent transport properties of water and ions. These copolymers can be used in a variety of topologies. Structure-property-performance relationships of these membranes as candidates for electrolysis of water for hydrogen production and for purification of water from dissolved ions have been studied.
Linear and multiblock sulfonated poly(arylene ether sulfone)s are potential alternative candidates to Nafion membranes for hydrogen gas production via electrolysis of water. In this investigation, these copolymers were prepared from the direct polymerization of di-sulfonated and non-sulfonated comonomers with bisphenol monomers. In systematic investigations, a series of copolymers with modified properties were synthesized and characterized by changing the ratio of the sulfonated/non-sulfonated comonomers in each reaction. These copolymers were investigated in terms of mechanical stability, proton conductivity and H2 gas permeability at a range of temperatures and under fully hydrated conditions.
A multiblock copolymer was synthesized and evaluated for its potential as membranes for electrolysis of water and for fuel cell applications. The multiblock copolymer contained some fluorinated repeat units in the hydrophobic blocks, and these were coupled with a fully disulfonated hydrophilic block prepared from 3,3'-disulfonate-4,4'-dichlorodiphenyl sulfone and biphenol. After annealing, the multiblock copolymer showed enhanced proton conductivity and a more ordered morphology in comparison to the random copolymer counterparts. At 90 oC and under fully hydrated conditions, improved proton conductivity and controlled H2 gas permeability was observed. Finally, the performance of the multiblock copolymer, which was measured as the ratio of proton conductivity to H2 gas permeability, was improved when compared to the state-of-the-art membrane, Nafion 212, by a factor of 3.
In another systematic study, two series of random copolymers were synthesized and characterized, and then cast into membranes to evaluate for electrolysis of water. One series contained solely hydroquinone as the phenolic monomer, while the second series contained a mixture of resorcinol and hydroquinone as phenolic comonomers. The polymers that contained only the hydroquinone monomer showed exceptionally good mechanical properties due to the para-substituted comonomer in the composition of the polymer. In the resorcinol-hydroquinone series, gas permeability was constrained due to the presence of 25% of the meta-substituted comonomer incorporated into its structure. Low gas permeability and high proton conductivity at elevated temperatures were obtained for both the linear random and multiblock copolymers. Performance of these copolymers was superior to Nafion at elevated temperatures (80-95°C). In order to enhance the durability of these materials in their hydrated states at elevated temperatures, the surfaces of these copolymer films were treated with fluorine gas. In comparison with pristine non-fluorinated membranes, the modified membranes showed decreased water uptake and longer durability in Fenton's reagent.
A series of linear and crosslinked copolymers were investigated with respect to their potential for use as membranes for desalination of water by electrodialysis and reverse osmosis. The crosslinked membranes were prepared by reacting controlled molecular weight, disulfonated oligomers that were terminated with meta-aminophenol with an epoxy reagent. The oligomers had systematically varied degrees of disulfonation and either 5000 or 10,000 Da controlled molecular weights. Membrane casting conditions were established to fabricate highly crosslinked systems with greater than 90% gel fractions. At such a high gel fraction, the water uptake of the crosslinked membranes was lower than that of the linear biphenol-based, disulfonated random copolymer with a similar IEC. Among these series of copolymers, it was shown that the crosslinked membranes cast from the oligomers with 50% degree of disulfonation and a molecular weight of 10,000 Da had the lowest salt permeability of 10-8 cm2/sec.
For desalination applications, a comonomer was synthesized with one sulfonate substituent on 4,4'-dichlorodiphenyl sulfone. This new monosulfonated comonomer allows for even distribution of the ions on the linear copolymer backbone, and this may be important for controlling ion transport. Mechanical tests were conducted on the membranes while they were submerged in a water bath. The ultimate strength of a fully hydrated copolymer with an IEC of 1.36 meq/g was approximately 60 MPa with an elongation at break of 160%. Moreover, in a monovalent/divalent mixed salt solution, the monosulfonated linear copolymer exhibited a constant Na+ passage of less than 1.0%.Ph. D.
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Martí, Calatayud Manuel César. « STUDY OF THE TRANSPORT OF HEAVY METAL IONS THROUGH CATION-EXCHANGE MEMBRANES APPLIED TO THE TREATMENT OF INDUSTRIAL EFFLUENTS ». Doctoral thesis, Universitat Politècnica de València, 2015. http://hdl.handle.net/10251/46004.
Résumé :
La presente Tesis Doctoral consiste en la determinación de las propiedades de transporte de diferentes especies catiónicas a través de membranas de intercambio catiónico. Las membranas de intercambio iónico son un componente clave de los reactores electroquímicos y de los sistemas de electrodiálisis, puesto que determinan el consumo energético y la eficiencia del proceso. La utilización de este tipo de membranas para el tratamiento de efluentes industriales no es muy extendida debido a los requisitos de elevada resistencia química y durabilidad que deben cumplir las membranas. Otro asunto importante radica en la eficiencia en el transporte de los iones que se quieren eliminar a través de la membrana. Normalmente, existe una competencia por el paso a través de las membranas entre diferentes especies debido al carácter multicomponente de los efluentes a tratar. Sin embargo, una mejora en las propiedades de las membranas de intercambio iónico permitiría la implantación del tratamiento mediante reactores electroquímicos de efluentes industriales con un contenido importante en compuestos metálicos, tales como los baños agotados de las industrias de cromado. La utilización de una tecnología limpia como la electrodiálisis conllevaría diferentes ventajas, entre las cuales destacan la recuperación de los efluentes para su reutilización en el proceso industrial, el ahorro en el consumo de agua y la disminución de la descarga de contaminantes al medio ambiente.
La determinación de las condiciones de operación óptimas así como la mejora de las propiedades de transporte de las membranas constituye el principal tema de la presente investigación. Para ello, se emplearán diferentes tipos de membrana. En primer lugar, se estudiará el comportamiento de las membranas poliméricas comerciales que poseen unas propiedades de resistencia química elevadas, las cuales se tomarán como referencia. De forma paralela, se producirán membranas conductoras de iones a partir de materiales cerámicos económicos, ya que la resistencia de los materiales cerámicos a sustancias oxidantes y muy ácidas es mayor que la de los materiales poliméricos. Este punto constituye la parte más innovadora de la investigación, puesto que la mayoría de las membranas de intercambio iónico comerciales están basadas en materiales poliméricos que no pueden resistir las condiciones específicas de los efluentes industriales. Una vez determinadas las condiciones de operación óptimas, se realizarán ensayos en plantas piloto con el fin de confirmar los resultados obtenidos mediante las técnicas de caracterización y determinar el grado de recuperación y coste energético asociado a los procesos electrodialíticos de tratamiento de efluentes industriales.Martí Calatayud, MC. (2014). STUDY OF THE TRANSPORT OF HEAVY METAL IONS THROUGH CATION-EXCHANGE MEMBRANES APPLIED TO THE TREATMENT OF INDUSTRIAL EFFLUENTS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/46004
TESIS
Premiado
30
Boulehdid, Hanae. « Elaboration et caractérisation d'une membrane cationique monosélective par modification chimique d'un film ETFE ». Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210555.
Résumé :
Ce travail porte sur l'amélioration de la sélectivité préférentielle d'une membrane cationique à base d’ETFE pour une utilisation en électrodialyse afin de traiter des effluents industriels contenant un mélange d’acides et de sels métalliques. Pour cela, nous avons fait appel à la méthode de la modification chimique de la surface d’une membrane cationique par la formation d’un film superficiel mince portant des charges positives afin de former une barrière de répulsion électrostatique pour des cations bivalents tout en permettant le passage de cations monovalents tels que les protons.La synthèse de la membrane cationique de base a été réalisée en passant par différentes étapes à savoir :le greffage du styrène - divinylbenzène (DVB), la chlorosulfonation et l’hydrolyse.
Au cours de ce travail, nous avons mis au point un protocole de greffage du styrène-DVB dans le film d’ETFE qui permet l’obtention d’un film ayant un taux de greffage reproductible assurant à la membrane cationique finale une bonne conductivité électrique et une capacité d’échange acceptable pour une membrane d’électrodialyse. Une étude de la réaction de greffage en fonction de la concentration en réticulant a été réalisée.
Nous avons procédé par la suite à la modification de la surface du film d’ETFE greffé styrène-DVB par la formation d’une couche superficielle mince fixée par des liens covalents. Les membranes modifiées ont été obtenues par la réaction d’une seule face du film d’ETFE greffé chlorosulfoné avec la 3-diméthylaminopropylamine. La modification chimique de la surface du film ETFE greffé chlorosulfoné a été suivie par la technique FTIR-ATR. L’effet de la concentration de la diamine sur les propriétés électrochimiques des différentes membranes modifiées a été étudié. La résistance électrique des membranes modifiées équilibrées au contact de solutions de chlorure de sodium et d'acide sulfurique a été mesurée par la technique d’impédance. La détermination du nombre de transport du proton et de l’ion sodium a été réalisée à partir de mesures du potentiel de membrane. La densité de courant limite des membranes a été évaluée sur base des courbes courant-tension. Les mesures de chronopotentiométrie ont été également effectuées sur les différentes membranes synthétisées.
Les résultats de ces caractérisations montrent que la modification de la surface engendre des changements considérables au niveau des propriétés électrochimiques des membranes résultantes. La résistance électrique, la densité de courant limite ainsi que les propriétés de transport de la membrane dépendent d’une part de la concentration de la diamine utilisée et d’autre part de la solution dans laquelle la membrane modifiée est équilibrée.
La sélectivité préférentielle des différentes membranes vis-à-vis des protons par rapport aux ions bivalents a été testée en réalisant des électrodialyses d’un milieu mixte H2SO4-NiSO4. Nos résultats montrent que la modification chimique de la surface de la membrane affecte d’une manière significative le transport des ions nickel tout en respectant le passage des protons. Une meilleure séparation a été obtenue pour une membrane modifiée en utilisant la diamine pure.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
31
Souza, Jadison Fabricio de. « Desenvolvimento de membranas de polissulfona para imobilização de lipase ». reponame:Repositório Institucional da UCS, 2006. https://repositorio.ucs.br/handle/11338/168.
Résumé :
Este trabalho teve por objetivo a preparação e caracterização de membranas de polissulfona (PSU) e a imobilização da enzima lipase nestes filmes, para a produção de membranas enantiosseletivas, visando utilização futura em separação de misturas quirais. Membranas de PSU foram preparadas pelo processo de inversão de fase, utilizando clorofórmio como solvente e água como agente coagulante para a inversão. Foram preparadas membranas com diferentes espessuras e os seguintes parâmetros para a inversão de fase foram definidos: concentração das soluções, tempo de evaporação do solvente, secagem e tratamento térmico. As membranas foram caracterizadas, visando a utilização em processo de eletrodiálise (ED) e imobilização da enzima lipase PS. Para a imobilização foi utilizado o glutaraldeído como agente bifuncional para ligação da enzima ao polímero. Na imobilização foram determinados os parâmetros cinéticos velocidade máxima (Vmáx) e constante de Michaelis-Menten (Km), a quantidade de enzima imobilizada nas membranas pelo método de Bradford e a atividade da enzima livre e imobilizada através da hidrólise do acetato de p-nitrofenila (PNPA). As membranas de PSU preparadas por inversão são hidrofóbicas, e apresentaram características de permesseletividade e capacidade de troca iônica inferiores às apresentadas pelas membranas comerciais Selemion®; CMT e CMV e resistência elétrica superior à destas membranas. O diâmetro dos poros nas membranas é menor que 100 nm. . A quantidade máxima de enzima imobilizada foi de 2,35 mg .g-1 de polímero em 18 horas de imobilização com um rendimento de 61,2%. A atividade da enzima decai após a imobilização, de 14780 U.g-1 (enzima livre) para 1184 U.g-1 (enzima imobilizada).Submitted by Marcelo Teixeira (mvteixeira@ucs.br) on 2014-05-13T17:21:10Z No. of bitstreams: 1 Dissertacao Jadison Fabricio de Souza.pdf: 3168334 bytes, checksum: ec62af877268ce2e7d357db5c8c5e372 (MD5)
Made available in DSpace on 2014-05-13T17:21:10Z (GMT). No. of bitstreams: 1 Dissertacao Jadison Fabricio de Souza.pdf: 3168334 bytes, checksum: ec62af877268ce2e7d357db5c8c5e372 (MD5)
Preparation and characterization of polysulfone (PSU) membranes and the immobilization of lipase enzyme in these membranes to produce enantioselective membranes, in order to separate chiral compounds, is the subject of the present work. PSU membranes were prepared by phase inversion, using chloroform as solvent and water as nonsolvent. Membranes with different thickness were prepared and phase inversion parameters such as (solution concentrations, solvent evaporation time, drying and thermal treatment) were investigated. Membranes were characterized, in order to use them in electrodialysis process (ED) and in the lipase PS enzyme immobilization. For immobilization, bifunctional agent glutaraldehyde was used to link the enzyme to the polymer. On immobilization, the kinetic constants (Km e Vmax), the amount of immobilized enzyme with Bradford method and the activity of free and immobilized enzyme with p-nitrophenyl acetate (PNPA) hydrolysis, were determined. PSU membranes prepared by phase inversion are hydrophobic and, when compared with Selemion®; CMT and CMV commercial membranes, present lower permeselectivity, lower ion exchange capability and higher resistance. Membranes pore diameter is lower than 100 nm. The maximum amount of immobilized enzyme in the membranes reached 2.35 mg per gram of polymer after 18 hours of immobilization with a 61,2% yield . Enzyme activity decays after immobilization , from 14780 U.g-1 (free enzyme) to 1184 U.g-1 (immobilized enzyme).
32
Patil, Rahul. « Membrane Processes for Sustainable Energy Applications ». University of Toledo / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1353077392.
33
Catonné, Jean-Claude. « Contribution à l'étude du défaut de sélectivité présenté par les membranes échangeuses d'anions, dans le cadre de leurs applications au traitement électrochimique de régénération des solutions aqueuses d'acides minéraux ». Paris 6, 1986. http://www.theses.fr/1986PA066030.
Résumé :
Essai d'identification de l'origine de la "fuite h+" et de celle des différentes sources susceptibles d'alimenter le mouvement d'eau au sein des membranes échangeuses d'anions, selon que le matériau est fortement ou non "élusterisé", puis d'établissement de l'existence d'une corrélation étroite entre l'intensité de fuite protonique et celle de la perméabilité osmotique des membranes (ainsi que le laisse prévoir la théorie de Gierke dans le cas des membranes échangeuses de cations). Et enfin, évaluation du rôle du champ électrique, ainsi que celui de la composition de l'électrolyte sur les résultats.
34
Io-MengFok et 霍耀明. « Treatment of High Salinity RO Concentrated Wastewater Using Bipolar Membrane Electrodialysis ». Thesis, 2019. http://ndltd.ncl.edu.tw/handle/g2ntjw.
35
Jiang, Chi-Lung, et 江其龍. « Energy Generation from a Salinity Gradient by Reverse Electrodialysis in Nanopores with Outer Membranes Modified with Bipolar Polyelectrolyte Brushes ». Thesis, 2015. http://ndltd.ncl.edu.tw/handle/x4d5xg.
Résumé :
碩士國立雲林科技大學
化學工程與材料工程系
103
Inspired by biological power conversion system, we theoretically investigate the power generation by the reverse electrodialysis (RED) through a salinity gradient in a solid-state nanopore with its outer membranes modified with biopolar surface charges and polyelectrolyte brushes, referred to as the bipolar solid-state and soft nanopores, respectively. In addition to salinity gradients, the influences of the nanopore length and the surface charge property of the inner pore wall are comprehensively discussed. Our results demonstrate that the surface modification of bipolar charges is capable of enhancing the energy density and the energy conversion efficiency. Compared to the conventional solid-state nanopore, the proposed bipolar soft nanopore exhibits a much higher energy output and conversion efficiency. If the inner wall of the nanopore is negatively charged, the energy output in the bipolar soft nanopore gets largest at a moderate pore length. A gaint osmotic energy density along with a maximum conversion efficiency up as high as 53.2 and 14.3 %, respectively, for a single biopolar soft nanopore with its inner pore wall of negative charges at are discovered. The results gathered suggest that the proposed bipolar soft nanopore can be a possible candidate used as membranes for osmotic power genrtation by the RED.
36
Hattingh, Cornelius Johannes. « Electrodialysis in flow injection systems ». Thesis, 2000. http://upetd.up.ac.za/thesis/available/etd-12042006-132952/.
37
Ribeiro, Pedro Daniel Porfírio. « Multistage Reverse Electrodialysis for Energy Production ». Master's thesis, 2020. http://hdl.handle.net/10362/105718.
Résumé :
The ever-increasing need for sustainable energy sources creates the necessity to research and develop renewable energies. An example of these is the salinity gradient energy (SGE), where power can be harvested from waters of different salinity. One type of SGE technology is Reverse Electrodialysis (RED), which was tested in this thesis in single and multistage (MSRED) setups in order to improve key parameters like power density and energy efficiency.
Simulations using a Phyton model developed at Wetsus showed that a multistage setup with 2 stacks in-series using 155 µm thickness spacers is superior to ones with 480 µm. This is due to greater energy efficiencies and gross power densities. A 3-stacks system was also studied for the 155 µm thick spacers, but the increase in efficiency did not compensate the loss in power density.
Experimental systems using stacks of dimensions 10 cm x 10 cm and 22 cm x 22 cm, both in a 2-stacks in-series setup were tested to attain the best combination of both net power density and energy efficiency. This was achieved at 20 seconds of residence time, in a multistage arrangement, with 0.821 W/m2 and 31.7 % for the smaller stacks, while the bigger ones achieved the best result in a single stage at a residence time of 44 seconds, with 0.748 W/m2 and 31.9 %, respectively.
Testing the 10 cm x 10 cm stacks with only 3 shielding cation exchange membranes, showed a blank resistance of 0.279 Ω, which likely means that it can be underestimating the parameters. Further studies should be performed using this correction or, preferably, employing more cell pairs, since the different possibilities multistage systems offer compared to single stacks allow for a bigger flexibility and thus an easier optimization of the key parameters, leading to a better process performance.
38
Tsung-ChenTsai et 蔡宗承. « Power Generation by Reverse Electrodialysis in Nanopore Membranes from a Microfluidic and Nanofluidic System ». Thesis, 2016. http://ndltd.ncl.edu.tw/handle/02664774512989023119.
39
Kotoka, Francis. « Fouling Monitoring and Mitigation of Monovalent Selective Anion Exchange Membranes to Be Used in Reverse Electrodialysis ». Master's thesis, 2020. http://hdl.handle.net/10362/128904.
Résumé :
Erasmus Mundus Master in Membrane Engineering for a Sustainable World (EM3E-4SW)Organic fouling phenomena predominantly restricts the behavior of Anion Exchange membranes (AEMs), thus reducing the obtainable net power density in reverse electrodialysis (RED). Consequently, we propose a monolayer surface modification of heterogeneous Ralex-AEMs with biocompatible poly(acrylic) acid (PAA) to enhance organic antifouling and monovalent membrane permselectivity. The AEMs were immersed in PAA aqueous solution for 24 h for surface modification. The modified membranes were physicochemical characterized via water contact angle (WCA), water uptake, ion exchange capacity, fixed charge density and swelling degree measurements. Their electrochemical characteristics were evaluated through cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The impact of recurring fouling and cleaning was assessed. Membrane fouling behavior and sulfate rejection were studied in the presence of humic acid (HA), using model NaCl aqueous solutions in a diffusion cell. The modified AEMs (PAA-AEMs) showed a sulfate rejection improvement by 36%-54%, and their hydrophilicity was enhanced by > 15 % with respective to their WCA values. The 3 g/L PAA based AEM achieved an antifouling resistance of 65.8% towards HA in comparison with the unmodified membrane. Recurring fouling and cleaning of the membranes was investigated using 25 ppm HA as the model foulant, and 0.1 M NaOH(aq) as the cleaning agent. In this case, the NaOH cleaning solution restored the membrane resistances almost to their original values after the first fouling and cleaning cycle. However, it failed in the second and third cycles due to the predominance of irreversible fouling and adsorption caused by the HA, leading to higher membrane resistance. Overall, the results demonstrate the technical feasibility of the proposed membrane surface modification procedure, and the need for efficient cleaning agents to mitigate fouling of AEMs. This study may therefore provide a viable approach to enhance RED process efficiency.
40
Mufula, Alain Ilunga. « Production of ion exchange membrane for hydrogen fuel cell ». Thesis, 2017. https://hdl.handle.net/10539/24237.
Résumé :
A thesis submitted to the Faculty of Engineering and the Built Environment,
University of the Witwatersrand, Johannesburg, in fulfillment of the
requirements for the degree of Doctor of Philosophy in Engineering.
Johannesburg, 2017Among of the components of the fuel cell, the polymer electrolyte membrane is critical to the performance and life time of the cell. Over the years the mechanical properties of the membrane, water management have tended to limit its wide spread commercialization as an alternative source of the renewable energy for portable power units. Fuel cell continues to attract extensive research interest as potential source of renewable energy. This work focuses on the production of ionexchange membrane (IEM) for hydrogen fuel cell, using cheap and locally available starting materials. The polystyrene-butadiene rubber (SBR) of different styrene and butadiene compositions, have been explored for functionality in fuel cell application. The production process was conducted in three stages: the first stage involved hydrogenation process followed by sulfonation process. The second stage entailed the production of carbon nano-spheres for the blending in the hydrogenated sulfonated polystyrene-butadiene rubber. The blending was also done between hybrid nanoparticles and hydrogenated sulfonated polystyrenebutadiene rubber. The third stage was the casting in thin film of blended solutions employing the evaporative method and the use of casting tape machine technique. The thin film was later on characterized and tested in a single fuel cell stack. Controlled hydrogenation of SBR employing catalytic method was achieved with maximum degree of hydrogenation in the range of: 90 – 92% for SBR with 23.5% styrene content and for SBR 25% styrene content 76 – 80% for SBR with 40% styrene content and 82 – 92% for SBR with 52% styrene content. The optimum conditions of this process were obtained using the Design of Experiments. SBR was also hydrogenated using a photocatalytic method and the percentage of hydrogenation for all SBR compositions used was found in the range between 60 and 74%. The hydrogenation results using the catalyst were higher compared to those obtained with the photocatalytic method. Therefore they were used to develop the kinetic model for prediction of hydrogenation process. Langmuir – Hinshelwood models were reviewed in this project as they explain these heterogeneous catalytic processes. Data from the kinetic tests were fitted to Langmuir – Hinshelwood models and reaction constants were found in the range between 0.445 h-1 and 0.610 h-1 for the reaction temperature between 20 and 30°C. The hydrogenated SBR of different compositions were effectively sulfonated with chlorosulphonic acid employed as first sulfonating agent of concentrations 0.15, 0.175 and 0.25M for SBR 23.5 and 25% styrene content, for SBR 40% styrene content and for SBR 52% styrene content, respectively. The degree of sulfonation was found in the range between 56 and 72% depending on the rubber composition. Trimethylsilyl chlorosulfonate used as the second sulfonating agent was like wise attached to the same polymer back bone and the degree of sulfonation was between 59 and 74% depending on the rubber’s styrene content. Non-conductive carbon nanospheres (CNS) of uniform size of about 46 nm were produced employing the non-catalytic chemical vapour deposition method at 1000°C. Acetylene and argon were respectively used as carbon source and carrier gas, in a reactor of 16 mm in diameter. Successful blending of 4 wt% nanoparticles and hydrogenated sulfonated styrene butadiene solution was accomplished by magnetic stirring technique combined with ultrasonication at 60% amplitude. The blended solution was casted to produce a thin film membrane of 156 μm thickness. Further the tensile strength test of the membranes has shown an increase in Young’s Modulus by 72-120% for all the rubbers. This test was done using TA.XTplus, Texture Analyser machine. The water uptake increment was in the range of 20-27% and thermal stability in the range of 2-20% depending on the rubber composition. Purchased electrodes from FuelCellsEtc (USA), were pasted on both sides of the membranes by the means of hot press at 125oC for about 5 minutes at a pressure of 40 kPa. The Membrane Electrode Assembly (MEAs) fabricated were tested in the fuel cell stack. The highest power density of approximately 85mW/cm2 was obtained for 52% styrene nanocomposite membrane with 4% hybrid nanoparticles at the current density of 212.41mA/cm2 and the efficiency was between 41 and 43%. MEA fabricated with Nafion112 membrane was tested and yielded the open cell voltage of 0.79V, power density of about 77.34mW/cm2 and efficiency of 45%. Results obtained disclose that the MEA with nanocomposites based SBR 52% styrene composition yielded higher power density and higher voltage than the one with Nafion 112 which is one of the fuel cell membranes available on the market. The results obtained revealed that the nanocomposite membranes with 4% hybrid nanoparticles (CNS + SiO2) had higher voltage than the one with 4% CNS. These optimum conditions obtained in this work may be adopted for a typical continuous production of the membrane for hydrogen fuel cell.
MT2018
41
Chang, Chien-Yu, et 張倩瑜. « The Separation and Purification of Recombinant Proteins from Transgenic Rice Cell Culture by Electrodialysis with Filtration Membranes ». Thesis, 2019. http://ndltd.ncl.edu.tw/handle/e2s9k6.
Résumé :
碩士元智大學
化學工程與材料科學學系
107
It is expected that electrodialysis with filtration membranes (EDFM) can effectively separate protein macromolecules based on the combined effect of molecular size and charge differences with filtration membranes and electrodialysis.A system of EDFM with proper selection of ultrafiltration (UF) membranes was established to test the feasibility of separation and purification of human serum albumin (HSA) from the medium of rice cell culture. The effects of the operating conditions such as operating voltage, current density, pH value on the performance were evaluated. The concentrations of proteins in the feed and permeate chambers were monitored by RP-HPLC. In a preliminary study, bovine serum albumin (BSA) as model, and is negatively charged with pH higher than pI in the feed solution. Therefore, BSA could be driven to the permeate side (anode) by an electric field at higher pH.BSA has higher electrophoretic coefficient (31.3 10-5 mg/V cm2 h) because of negative charge. HSA could be recovered from the medium of rice cell culture by our technology at right conditions.The results demonstrate that recovery of HSA from rice cell culture would be possible with proper selections of filtration membranes, pH, and operating electrical field by EDFM process.
42
Rankin, Daniel Justin. « Entrance effects on solution transport through nanoporous membranes ». Thesis, 2019. http://hdl.handle.net/2440/119956.
Résumé :
Solution transport across nanoporous membranes occurs in many different biologically and industrially relevant processes such as filtration of waste by the kidneys and desalination of seawater. The same theoretical framework can be used to understand both of these processes, as well as many others. In general, a flux of solution is driven across a porous membrane due to an externally applied force. This external force can be a gradient in pressure, temperature, concentration, or electrical potential. At the entrance and exit of a pore the fluid streamlines and electric field lines experience a significant constriction in going from the bulk reservoirs to the narrow pores. This effect can become significant for short pores and pores with low friction and thus must be appropriately taken into account to correctly predict solution fluxes. In the first study, continuum mechanics is used to investigate the entrance effects on charge flux of electrolytes across porous membranes. The access electrical resistance, which is the electrical resistance associated with the electric field lines bending into and out of the pores, has previously been shown to make up a significant fraction of the total electrical resistance when the fluid–pore friction is low.1 Although several papers have studied the access electrical resistance,2–5 none has explicitly considered the effect of surface charge on the surfaces of the membrane facing the bulk solution even though this charge has been shown to have a significant effect on the access electrical resistance.6 In this thesis, finite element method (FEM) calculations are carried out in order to systematically study the access electrical resistance of charged pores in charged and uncharged membranes. The results are compared with predictions from two existing continuum-based theories and a new theory derived in this thesis. It is found that the FEM results agree with different theories depending on whether or not the outer-membrane surface is charged. In the second study an existing molecular dynamics (MD) algorithm is used to simulate concentration differences across pores connected to bulk reservoirs. The algorithm is found to require a modification at high solute concentrations, which had not previously been considered. In the third study the modified MD algorithm is used to investigate possible non-continuum and non-ideal effects on concentration-gradient-driven flows at high solute concentrations. Entrance effects are considered in the context of diffusio-osmotic flows, which are flows driven by forces acting on the inhomogeneous fluid layer near the membrane pore surfaces as a result of an applied concentration gradient. The access diffusio-osmotic resistance, which is the resistance to the diffusio-osmotic flux associated with the fluid streamlines bending into and out of the pores, is calculated and compared with a new theory that is derived in this thesis. The assumptions made in deriving the new theory include, amongst others a dilute solution and continuum theory. Despite these assumptions, the theory predicts the correct scaling of the MD results at two different high solute concentrations. It is found that both electrical and diffusio-osmotic access resistances can be separated from their respective total (access and pore) resistances. Depending on whether the length scales of interest, such as the pore radius, are comparable with the pore length, the access resistance can be a significant factor in determining the total resistance of the system. This is explored in this thesis in the context of both electrical and diffusio-omsotic resistance, which affect a wide range of different systems.Thesis (MPhil) -- University of Adelaide, School of Physical Sciences, 2019
43
Pereira, Ana Catarina de Jesus Pais. « Deregulated inflammasome in Bipolar Disorder (BD) : a matter of stress ? » Master's thesis, 2018. http://hdl.handle.net/10316/86272.
Résumé :
Dissertação de Mestrado em Biologia Celular e Molecular apresentada à Faculdade de Ciências e TecnologiaOs problemas de saúde mental constituem a principal fonte de carga económica mundial, estimando-se que o custo global seja superior ao das doenças cardiovasculares, cancro ou diabetes, quando consideradas individualmente. Na União Europeia, as doenças mentais afetam milhões de pessoas e prevê-se que esses números aumentem devido ao envelhecimento da população. A doença bipolar (DB) é um distúrbio mental que se caracteriza por oscilações de humor entre depressão e mania, resultando em danos cognitivos e funcionais que requerem tratamento contínuo. No entanto, os escassos tratamentos atualmente disponíveis apresentam eficácia limitada e o diagnóstico tardio é frequente devido à ausência de marcadores biológicos. Assim, é fundamental compreender a fisiopatologia da DB para a implementação de novos fármacos na prática clínica, bem como para o desenvolvimento de biomarcadores que possibilitem um diagnóstico mais preciso e precoce. Dado que a DB parece estar intimamente associada ao stresse do retículo endoplasmático (RE) e aos mecanismos para o enfrentar ao longo da sua progressão, propôs-se que as estratégias de resiliência celular desenvolvidas pelas células para lidar com o stresse desempenham um papel crucial na DB. Interessantemente, demonstrou-se que as junções RE-mitocôndria, designadas “Mitochondria-Associated Membranes” (MAMs), são fundamentais nas respostas ao stresse uma vez que modulam a função mitocondrial, a sinalização de cálcio, a via Unfolded Protein Response (UPR) induzida pelo stresse do RE e a ativação do inflamassoma, os quais representam marcadores fisiopatológicos da DB. Estas premissas constituíram o ponto de partida para este trabalho, que é focado na “hipótese MAM” proposta pelo nosso grupo para a fisiopatologia da DB, e que pretende investigar o papel do stresse do RE na ativação do inflamassoma NLRP3 e na subsequente libertação de mediadores pró-inflamatórios que certamente sustentam o estado pro-inflamatório associado à DB. As MAMs foram avaliadas como o elo de ligação subjacente ao eixo RE-inflamassoma na DB. Neste sentido, utilizou-se um modelo celular do sistema imune inato, nomeadamente monócitos isolados de doentes bipolares versus controlos saudáveis em condições basais ou expostos a stresse do RE, assim como a linha celular de monócitos humanos THP-1 que foi usada como um modelo in vitro para elucidar as consequências funcionais e morfológicas do stresse do RE. Os nossos resultados sugerem que o stresse do RE induz a ativação do inflamassoma NLRP3 em monócitos THP-1 e em monócitos de indivíduos com diagnóstico de DB (fase precoce). Enquanto que nas células THP-1 o stresse do RE atua como sinal 2 para a ativação do inflamassoma, nos monócitos primários de doentes bipolares e de controlos saudáveis atua como sinal 1 e 2. Além disso, apurámos que os monócitos de doentes previamente expostos a LPS são mais sensíveis ao stresse do RE do que os monócitos controlo o que, juntamente com os parâmetros analíticos analisados, sugere que os doentes bipolares são mais suscetíveis a um estado pró-inflamatório. Evidenciámos ainda que os contactos RE-mitocôndria ao nível das MAMs, em particular a chaperona Sigma-1R e a proteína de ligação Mitofusina 2, são afetados pelo stresse do RE tanto nas células THP-1 como nos monócitos de doentes bipolares. Os resultados obtidos nos monócitos THP-1 sugerem que a comunicação RE-mitocôndria em células submetidas ao stresse promove a ativação do NLRP3 através de um mecanismo independente da produção mitocondrial de espécies reativas de oxigénio, o qual parece ser parcialmente mediado pela despolarização da membrana mitocondrial e subsequente externalização de cardiolipina. Também se observou que o stresse do RE provoca alterações morfológicas em monócitos THP-1 compatíveis com RE dilatado, indução da autofagia/mitofagia e modulação da dinâmica mitocondrial. Este trabalho evidenciou a disfunção das MAMs como um potencial elo fisiopatológico entre o stresse do RE e a ativação do inflamassoma NLRP3 no sistema imune inato, abrindo assim novos horizontes para o desenvolvimento de estratégias terapêuticas ajustadas à DB.
Mental health problems constitute the largest single source of world economic burden, with an estimated global cost greater than cardiovascular disease, cancer or diabetes individually. In the European Union, mental disorders affect millions of people and these numbers are expected to rise due to population ageing. Bipolar disorder (BD) is a mental illness characterized by mood swings between depression and mania resulting in cognitive and functional impairments that require lifetime treatment. However, few treatments are currently available with limited efficacy and delayed diagnosis is frequent because biomarkers are absent. Therefore, a better understanding of BD pathophysiology is crucial for new drugs design and implementation in clinical settings as well as to develop biomarkers for a more accurate and earlier diagnosis.Given that BD may be intimately associated with endoplasmic reticulum (ER) stress and coping mechanisms over the illness course, it has been proposed that cellular resilience strategies developed by cells to cope with stress play a key role in BD. Interestingly, it was shown that ER-mitochondria junctions, the so-called “Mitochondria-Associated Membranes” (MAMs), are relevant for stress-related responses by modulating mitochondrial function, Ca2+ signaling, ER stress-induced Unfolded Protein Response (UPR) and inflammasome activation, which are pathophysiological hallmarks of BD. These assumptions were the starting point for this work, which is focused on the “MAM hypothesis” proposed by our group for BD pathophysiology that intends to unveil the role of ER stress in NLRP3 inflammasome activation and subsequent release of pro-inflammatory mediators that will certainly sustain a pro-inflammatory status, as well as to evaluate MAMs as the link behind the ER stress-inflammasome axis in BD. For this purpose, a patient-derived cellular model of the innate immune system was used, namely monocytes isolated from BD patients versus healthy controls exposed to basal or ER stressful conditions and, the THP-1 monocytic cell line was used as in vitro model to decipher the functional and morphological consequences of ER stress. Altogether, our results suggest that ER stress induces NLRP3 inflammasome activation in THP-1 monocytes and BD patient-derived monocytes (early-stage). While in THP-1 cells ER stress acts as signal 2 for NLRP3 inflammasome activation, in control and BD monocytes it works as signal 1 and 2. In addition, LPS primed-BD patients’ monocytes are more responsive to ER stress than control monocytes, which together with the analytical parameters analyzed indicate that BD patients are more susceptible to develop a pro-inflammatory status. Furthermore, we uncovered that ER-mitochondria contacts at MAMs, particularly the chaperone Sigma-1R and the tethering protein Mitofusin 2, are affected in THP-1 cells as well as in BD monocytes upon ER stress. Data obtained in THP-1 monocytes suggest that ER-mitochondria communication in ER stressed cells promotes NLRP3 activation by a mitochondrial reactive oxygen species (ROS)-independent mechanism and, might be partially mediated by mitochondria membrane depolarization and subsequent externalization of cardiolipin. It was also observed in THP-1 monocytes that ER stress evoked morphological alterations consistent with dilated ER, autophagy/mitophagy induction and modulation of mitochondrial dynamics. This work pointed out MAM’s dysfunction as a potential pathophysiological link between ER stress and NLRP3 inflammasome activation in the innate immune system thus opening new avenues for the development of fine-tuned therapeutic strategies for BD.
44
Sheng-DeLi et 李聖德. « Preparation of Bipolar Membranes Using Plasma-Induced Polymerization Method on Hydrogen Production from Water Electrolysis ». Thesis, 2010. http://ndltd.ncl.edu.tw/handle/86052989427337492612.
Résumé :
博士國立成功大學
化學工程學系碩博士班
98
Bipolar membranes have a lot of industrial applications because of their extraordinary properties. Generally speaking, they could be used to the fields of producing acid/base solutions, water treatment (ex. Separate to recycle and purify inorganic acid/base solution, organic acid and organic materials) and food industry. Therefore, industrial and academic researchers have attracted considerable attentions on this field. It is emphasized that bipolar membranes possess a characteristic property of the electrical field-enhanced water dissociation. As a result, the aim of the research is to investigate the surface modification of the PVDF membrane to form the bipolar membranes after plasma treatment and subsequently using the bipolar membranes to hydrogen production from water electrolysis. In the first section of this study, the G-I, AA and SSS monomers were grafted onto the respective side of the PVDF or PES membranes after plasma treatment and then, the four kinds of the bipolar membranes have been successfully prepared by plasma-induced polymerization method (PVDF-g-G-I, AA-PVDF-G-I, SSS-PVDF-G-I and PES-g-G-I bipolar membranes). PES membrane as diaphragms was used as background experiment and marked as“Water”. The reason is that the result of the electrochemical properties for PES membrane used was the same as that for no membrane between the electrodes. Take PVDF-g-G-I bipolar membrane as an example, it was carried out the measurements of the ability to produce acid/base solution and hydrogen production from water electrolysis. In producing acid/base solution, the critical voltage of water splitting to H+ and OH- could be reduced to 0.88 V by using the PVDF-g-G-I bipolar membrane. In addition, the value of the critical voltage by using the PVDF-g-G-I bipolar membrane was the same when the electrolyte concentration was increased or the kinds of the electrolyte was altered. On the other hand, the value of the limiting current density was increased with the KCl concentration and the diffusion coefficient of the electrolyte. There are two reasons for lower current efficiency of the PVDF-g-G-I bipolar membrane. (1) when water dissociation was occurred, H2O was dissociated into H+ and OH- within it. H+ was migrated to cathode electrode and OH- was moved to anode electrode under the electrical field. The negative charge on cation exchange layer was neutralized by H+ ion. Contractly, the positive charge on anion exchange layer was neutralized by OH- ion. (2) The fixed charge concentration on the PVDF-g-G-I bipolar membrane was reduced in the solution phase due to high swelling ratio. It is divided from two part of hydrogen production from water electrolysis. One part is to change the base membranes and second part is to alter cation exchange layers of the PVDF-g-G-I bipolar membrane (using AA (-COO-) and SSS (HSO3- ) monomers). The performance of water electrolysis for the cell operated with or without the self-made bipolar membranes is demonstrated by measuring the cell voltage, H2 production efficiency and the energy consumption of the H2 generation. The cell voltage using the self-made bipolar membranes is obviously lower than that of Water. The data demonstrates that the bipolar membranes prepared by plasma-induced polymerization had a great ability to reduce the cell voltage of water electrolysis and H2 production efficiency was improved 10-20 % by using them (compared with Water). The reason is due to the effect of the electrical field-enhanced water dissociation. From the energy consumption of H2 production, an energy saving of 30 % could be reached for the cell operated with the self-made bipolar membranes (compared with Water). In the second section of this study, it was the design of the reactor of water electrolysis. The ultrasonic field was applied into water electrolysis to remove the bubbles gas adhering onto the surface of the electrodes, membrane and in the solution. By removing the bubbles gas, the ohmic drop was reduced. The performance for the cell operated with or without an ultrasonic field is demonstrated by measuring the reduction in cell voltage, the efficiency and energy consumption of the generated gas (Water system). The reference sample was based on Water system for the cell operated without an ultrasonic field. The reduction in cell voltage was 320, 100 and 75 mV under 0.1, 0.5 and 1.0 M NaOH when current density is 200 mA/cm2, respectively. H2 production efficiency was improved 5-18 % in the presence of an ultrasonic field and however, O2 production efficiency was reduced a little bit. It is due to the difference between the dynamic behavior of H2 and O2 gas adhering onto the electrodes. For the energy consumption of H2 production, it could be reduced 10-25 % under an ultrasonic field. From economic consideration, the ultrasonic field applied into alkaline water electrolysis was beneficial to energy efficiency of water electrolysis. Finally, the ultrasonic field and the self-made bipolar membranes were combined to improve H2 production from water electrolysis. Take the PVDF-g-G-I bipolar membrane as an example, the energy consumption of H2 production was obviously reduced 4-8 % for the cell operated with the ultrasonic field (in comparison with Water), respectively.
45
JouLi et 李柔. « Preparation of various ionic bipolar membranes using plasma-induced polymerization method on hydrogen production from water electrolysis ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/40208559048294440720.
Résumé :
碩士國立成功大學
化學工程學系碩博士班
100
Bipolar membranes are widely used in industry. They were usually used to produce the acid/base solutions and water treatment. Therefore, bipolar membranes have been attracted industrial and academic research. Reducing the cell voltage of water electrolysis by using bipolar membrane had proved by our laboratory. Consequently, the aim of this research is to investigate the surface modification of PVDF membranes by plasma treatment and alter various ionic monomers to form four kinds of bipolar membranes for hydrogen production from water electrolysis. In this study, the N,N-Dimethyl amino ethyl acrylate (DMAEA)、4-Vinyl pyridine (4-VP), 4-Styrene sulfonic acid sodium salt hydrate (SSS)、acrylic acid (AA) monomers were grafted onto the respective side of the PVDF membranes through the plasma treatment. Four kinds of bipolar membranes, DMAEA-PVDF-SSS、DMAEA-PVDF-AA、4VP-PVDF-SSS and 4VP-PVDF-AA bipolar membranes, have been successfully prepared by plasma-induced polymerization method after characteristic of FTIR and SEM. Poly-ethersulfonate (PES) membranes were used as background experiment (Water). In water electrolysis experiment, the cell voltage using four kinds of bipolar membranes is lower than PES membrane (Water). Among those bipolar membranes, DMAEA-PVDF-SSS bipolar membrane has lowest critical voltage of water splitting to H+ and OH- as 0.92V. On the other hand, the limiting current density was increased with the increasing of KCl concentration. Furthermore, H2 production efficiency can be improved 10-30% (compared with Water). When using the DMAEA-PVDF-SSS bipolar membranes in water electrolysis, the H2 production efficiency can be as high as 92% but it is just only 74% by 4VP-PVDF-SSS bipolar membranes. The result is attributed from the electrical field, water dissociation constant ratio and their physical properties. In the energy consumption of H2 production, DMAEA-PVDF-SSS bipolar membranes have great outcome, it can save 48% energy. Consequently, the effect of anion exchange layer on the water electrolysis is larger than that of cation exchange layer of bipolar membranes.
46
Jhih-JyunMai et 麥智鈞. « Preparation of bipolar membranes by plasma-induced polymerization for the application of hydrogen production from water electrolysis ». Thesis, 2019. http://ndltd.ncl.edu.tw/handle/hw8kjz.
47
Cunha, Ana Rita Azevedo Henriques da. « Perturbation of ER-mitochondria crosstalk in bipolar disorder : effect of Sigma-1 receptor modulation ». Master's thesis, 2021. http://hdl.handle.net/10316/98013.
Résumé :
Dissertação de Mestrado em Biologia Celular e Molecular apresentada à Faculdade de Ciências e TecnologiaOs distúrbios psiquiátricos têm um enorme impacto tanto na qualidade de vida dos doentes, como a economia global. Só na Europa existem cerca de 164 milhões de pessoas com diagnóstico de algum tipo de distúrbio psiquiátrico. O distúrbio bipolar é uma perturbação de humor caracterizada pelas alterações entre episódios depressivos e maníacos ou hipomaníacos. O conhecimento relativo aos mecanismos celulares e moleculares subjacentes ao distúrbio bipolar são ainda muito limitados. Até então, a maioria dos estudos foram realizados em tecido post-mortem de doentes ou em animais, possuindo grandes limitações para o desenvolvimento de terapias e biomarcadores. No entanto, a literatura aponta para que existam alterações da resposta ao stress do retículo endoplasmático, disfunção mitocondrial, e alterações nos processos de inflamação, sinalização de Ca2+, bioenergética, autofagia e apoptose. Estes processos são regulados por zonas de junção entre o retículo endoplasmático e a mitocôndria, denominadas mitochondria-associated membranes (MAMs) cuja relevância em diferentes doenças do cérebro tem vindo a ser desvendada. Tendo isto em conta, este trabalho visou revelar se os alguns dos eventos regulados pelas MAM se encontram alterados em fibroblastos derivados de doentes com distúrbio bipolar, nomeadamente na resposta ao stress do retículo endoplasmático, ao nível do contacto entre este organelo e a mitocôndria, na disfunção mitocondrial, e na sinalização de Ca2+. Para este fim, foram usados fibroblastos da derme a partir de biópsias de pele realizadas em doentes com BD ou sujeitos saudáveis (n=3 homens, com idades compreendidas entre os 18-25 anos) após consentimento informado, de acordo com as diretrizes do Comité de Ética. As células foram sujeitas a tratamentos com tapsigargina, um indutor clássico do stress do retículo endoplasmático, e com pridopidina, um agonista do recetor Sigma-1, que é uma proteína envolvida nos mecanismos das MAM. Em condições basais e em stress induzido pela tapsigargina, analisamos os níveis proteicos de marcadores de unfolded protein response (UPR) por Western-blotting. A viabilidade celular foi avaliada pelo ensaio de redução do MTT, e o potencial da membrana mitocondrial foi avaliado utilizando TMRE. A libertação de Ca2+ do retículo endoplasmático mediada por IP3R e a transferência de Ca2+ do retículo endoplasmático para a mitocôndria foram analisados através das sondas fluorescentes Fura-2 e Rhod-2, respetivamente. A ligação do retículo endoplasmático às mitocôndrias foi analisada utilizando proximity ligation assay. Em fibroblastos provenientes de doentes com distúrbio bipolar detetámos diferenças nos níveis de proteínas envolvidas na resposta ao stress do retículo endoplasmático, na ligação entre este organelo e a mitocôndria, e ainda na sinalização de Ca2+ para a mitocôndria, tanto em condições basais como em stress. No entanto, observámos que a ativação farmacológica do recetor Sigma-1 não alterou a reposta das células dos doentes bipolares. Os nossos estudos revelaram mecanismos celulares e moleculares alterados nos fibroblastos de doentes relativamente aos fibroblastos controlo. Estes resultados contribuirão para o desenvolvimento de biomarcadores fidedignos e de estratégias terapêuticas.
Psychiatric disorders greatly impact both the quality of life of patients and the global economy. Only in Europe, there are about 164 million people diagnosed with some type of psychiatric disorder. Bipolar disorder (BD) is a mood disorder characterised by changes between depressive and manic or hypomanic episodes. Knowledge regarding the cellular and molecular mechanisms underlying bipolar disorder are still very limited. Until then, most studies have been carried out in post-mortem tissue of patients or in animals, with major limitations for the development of therapies and biomarkers. However, the literature points to altered endoplasmic reticulum stress response, mitochondrial dysfunction, and abnormalities in the processes of inflammation, Ca2+ signaling, bioenergetics, autophagy, and apoptosis. These processes are regulated by mitochondria-associated membranes (MAMs) and their relevance in different brain diseases is being unravelled. Taking this into account, this work aimed to reveal whether some of the events regulated by MAMs are altered in fibroblasts derived from patients with bipolar disorder, namely in the endoplasmic reticulum (ER) stress response, the contacts between this organelle and mitochondria, in mitochondrial dysfunction, and in Ca2+ signaling. For this purpose, dermal fibroblasts were generated from skin biopsies performed in BD patients or age- and sex-matched control subjects (n=3 males, aged 18-25 years) after informed consent in accordance with Ethics Committee’s guidelines. The cells were subjected to treatments with thapsigargin, a classical inducer of ER stress, and with pridopidine, an agonist of the Sigma-1 receptor which is a protein involved in MAMs mechanisms. Under basal and thapsigargin exposure, protein levels of ER stress- induced unfolded protein response (UPR) markers were measured by Western-blotting. Cell survival was assessed by the MTT reduction assay, and the mitochondrial membrane potential was evaluated using TMRE. IP3R-mediated ER Ca2+ release and ER-mitochondria Ca2+ transfer were studied with the Fura-2 and Rhod-2 fluorescent dyes, respectively. ER-mitochondria tethering was analysed using the proximity ligand assay. In BD patients-derived fibroblasts we detected differences in the levels of proteins involved in the ER stress response, in ER-mitochondria tethering, and in Ca2+ signaling to mitochondria, both in basal and stress conditions. However, we found that pharmacological activation of the Sigma-1 receptor did not alter the response of bipolar patients’ cells. Our studies have revealed abnormal cellular and molecular mechanisms in bipolar patients’ fibroblasts that could contribute to the development of reliable biomarkers and therapeutic strategies.
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