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.

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.

L'utilisation croissante d'acides organiques dans l'industrie alimentaire, chimique et pharmaceutique entraîne le développement de nouvelles technologies pour leur isolement, séparation et concentration à partir de solutions complexes. Les procédés électro-membranaires constituent une voie prometteuse. Afin d'intensifier ces procédés, il est nécessaire de mieux comprendre les mécanismes de transport de la solution d'ampholytes dans le système électromembranaire souvent couplé à des réactions chimiques. La composition des formes ioniques peut en effet varier en fonction du pH de la solution. Les principaux objectifs de ce travail sont l'étude du comportement des systèmes membranaires contenant des solutions d'ampholytes dans un état d'équilibre (sans force de transfert ou sous très faible courant alternatif), et hors d'équilibre en régime d'électrodialyse (application d'un courant). Dans les deux cas, l'approche comprend une partie expérimentale et une partie théorique de caractérisation de transport de solution complexe. Dans la cadre de la modélisation associée, on a développé un modèle de système membranaire qui permet d'accéder à la distribution des formes d'ampholyte à l'intérieur et à l'extérieur de la membrane en fonction des paramètres externes.Les résultats de la comparaison des données expérimentales et de simulation de systèmes membranaires montre et explique les spécificités des mécanismes de transfert des ions d'ampholyte associés aux changements du pH de la solution au cours de l'électrodialyse. / The wide application of organic acids in the food, chemical and pharmaceutical industry is responsible for the increased interest in the development of new technologies for their isolation, separation and concentration from the complex solutions. The electro-membrane processes are promising. The difficulty to understand the transport mechanisms of the amphoteric solution in the electromembrane system is the coupling of chemical reactions: the ionic forms composition can vary depending on the pH of the solution.The main objectives are the study of the behavior of membrane systems containing ampholyte solutions in a steady state (without transfer force or under very low AC) and in a non-equilibrium state such as in electrodialysis regime (applying a current). In both cases, a study includes the experimental and theoretical parts of characterization of the complex solution transport. In the context of modeling a model of the membrane system which can calculate the ampholyte form distribution inside and outside the membrane depending on the external parameters was developed.The comparison of experimental data and results obtained from the simulation of membrane systems containing ampholytes solutions, shows and explains the specific features in the transfer mechanism of ampholyte ions which associated with changes of the solution pH during electrodialysis and, as a consequence, with modification of ampholyte forms.

Fundamental understanding of water transport and morphology is critical for improving ion conductivity in polymer electrolyte membranes (PEMs). Herein, we present comprehensive water transport measurements comparing anion-exchange membranes (AEMs) based on ammonium-functionalized poly(phenylene oxide) and cation-exchange membranes (CEMs) based on sulfonated poly(ether sulfone). We investigate the influence of counter ions, alkyl side chain, and degree of functionalization on water transport in AEMs and CEMs using pulsed-field-gradient (PFG) NMR diffusometry. Water diffusion in both AEMs and CEMs exhibit specific trends as a function of water uptake (wt%), indicating morphological similarities across common chemical structures. Furthermore, restricted diffusion reveals micron-scale heterogeneity of the hydrophilic network in both CEMs and AEMs. We propose a model wherein the hydrophilic network in these membranes has micron-scale distributions of local nm-scale dead ends, leading to changes in tortuosity as a function of water content, counterion type, and polymer structure. We furthermore parse tortuosity into two regimes, corresponding to nm-to-bulk and µm-to-bulk ranges, which reveal the importance of multi-scale morphological structures that influence bulk transport. This study provides new insights into polymer membrane morphology from nm to µm scales with the ultimate goal of controlling polymeric materials for enhanced fuel cells and other separations applications / MS / Using clean energy in place of fossil fuels to reduce carbon dioxide emissions is one of the biggest challenges of the 21st century. Among emerging technologies, fuel cells (FCs) show tremendous potential to be a candidate for the energy of the future. An FC is “an electrochemical device that directly converts chemical energy into electrical energy” with the only byproduct being heat and water. The key component of an FC is a polymer-electrolyte membrane, which helps to separate electrons and fuel and allows ions to move through. The current commercial membranes, named cation-exchange membranes (CEMs), employ precious metals such as platinum (Pt) as a catalyst, significantly increasing the cost. Anion exchange membranes (AEMs) are another alternative currently being investigated to reduce the cost of FCs because they can employ cheaper catalysts such as nickel or silver. This thesis investigated the motion of water inside AEMs and CEMs, and proposed a model to explain how water transports in these membranes. The result of this study provides new insights into polymer membrane internal structure with the ultimate goal of controlling polymeric materials for enhanced fuel cells and other separations applications such as reverse-osmosis water purification.

AN ABSTRACT OF THE DISSERTATION OFElizabeth W. Salako, for the Doctor of Philosophy degree in Chemistry, presented on March 27, 2024, at Southern Illinois University Carbondale. TITLE: SYNTHESIS OF NOVEL PERFLUORINATED ION EXCHANGE MEMBRANES AGAINST HYDROGEN PEROXIDE DEGRADATION IN ELECTROCHEMICAL ENERGY STORAGE DEVICES MAJOR PROFESSOR: Dr. Yong GaoThe continuous burning of fossil fuels to meet the energy needs of the ever-growing population has extensive and enduring effects on the environment, human health, and the economy. Adopting cleaner and more sustainable energy sources is crucial to reducing the impact and tackling the difficulties posed by climate change. Renewable energy, which is derived from sources that are naturally replenished, presents a compelling solution to address these pressing challenges. Due to the inherent intermittency of renewable energy available, which relies on weather conditions and daylight hours, incorporating energy storage technology into the power grid can effectively handle unforeseeable power demands.An ion exchange membrane (IEM) is an important part of electrochemical energy storage and conversion devices like fuel cells, flow batteries, and electrolyzers. Without it, these devices would not work properly. The IEM has significantly enhanced these devices by enabling higher operating temperatures and improving their durability and efficiency. The proton exchange membrane (PEM) has been greatly studied, with Nafion® (a product of DuPont) as the state-of-the-art membrane. Even though Nafion®, which belongs to the perfluorosulfonic acid (PFSA) group, has been commercialized, it suffers from low working temperatures, high cost, low tolerance to fuel impurities, and most importantly, degradation of the membrane over a short period of time. The membrane undergoes three main types of degradation: mechanical, thermal, and chemical degradation. Although the mechanical and thermal degradation of the membranes can be managed, the chemical degradation is a more intricate and challenging issue to address. The degradation of Nafion® occurs through the process of radical-induced disintegration of the polymer structure. This selectively targets the weakest points in the polymer structure, thereby fragmenting the polymer and leading to a loss of ionic conductivity. These vulnerable sites include carboxylic acid groups, C-S linkages, tertiary carbons, and fluoro-ether groups. Studies have shown the fluoro-ether groups to be more susceptible to hydroxyl radical attacks. In our aim to reduce membrane degradation, we designed and synthesized novel fluoro-monomers void of the fluoro-ether groups. We used the emulsion polymerization process in a high-pressure reactor to polymerize our synthesized monomers with a commercially available monomer to make different ionomers with -SO3H and -PO3H2 ion exchange groups. We measured the molecular weight of the polymers through the viscometry method. The mechanical properties of the polymers were not as great, and it became difficult to cast them into a thin film. Polytetrafluoroethylene (PTFE) films were used as a support for the polymers to make them stronger and to also measure their ion conductivities in comparison with NafionTM 115. Fenton’s test was employed to measure the susceptibility of the polymers to hydroxyl radical attack. Our polymers were not as good at conducting ions as NafionTM 115, but they were better at protecting against hydroxyl radical attacks, both at room temperature and higher temperatures. The results showed an inverse relationship between the number of fluoroalkyl ether groups present in the polymers and their resistance to hydroxyl radical attacks.

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 contrôlé / The 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

Une étude comparative des caractéristiques statiques, dynamiques et structurale a été menée sur 8 membranes échangeuses d'ions (MEIs), 4 neuves (MEIN) et les mêmes usagées (MEIU) après 2 ans de fonctionnement en ED dans l'industrie agroalimentaire. L'objectif essentiel était de mieux connaître les mécanismes de vieillissement in situ. Nous avons donc mesuré pour chacune de ces MEIs la capacité d'échange, la teneur en eau, la perméabilité ionique, la conductivité électrique, le nombre de transport, l'angle de contact, le courant limite, le module d'Young et la résistance à la traction. Aussi, nous avons effectué des analyses d'IRTF, de MEB et d'EDX. Cette étude nous a permis de conclure que (i) la MEC2 est restée presque stable après les 2 ans d'ED, alors que la MEA1 s'est très fortement dégradée. D'une manière générale, les MEAs sont plus sensibles au vieillissement que les MECs, (ii) les sites fonctionnels sulfoniques s'éliminent de la MEC. Nous ne pouvons pas affirmer ce mécanisme dans le cas des MEAs, mais nous soupçonnons un phénomène d'empoisonnement des sites fonctionnels, (iii) les MEAs se colmatent en surfaces avec des ampleurs différentes entre la MEA1 et la MEA2 / A comparative study of static characteristics, dynamic and structural was conducted on 8 ion-exchange membranes (MEIS), 4 new (IEMN) and the same used (IEMU) after two years of ED operation in the food industry. The main objective was to better understand the mechanisms of in situ ageing. We therefore measured for each IEMs exchange capacity, water content, ionic permeability, electrical conductivity, transport number, contact angle, current limit, Young's modulus and tensile strength. Therefore, we performed analysis of FTIR, SEM and EDX. This study concluded that (i) CEM2 remained almost stable after 2 years of ED, while AEM1 has sharply deteriorated. In general, the AEMs are more susceptible to ageing than CEMs, (ii) the sulfonic functional sites are eliminated from the CEMs. We cannot confirm this mechanism in the case of AEMs, but we suspect a poisoning phenomenon of functional sites, (iii) the AEMs fouled in surfaces with different degrees between AEM1 and AEM2

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 hydrogènes / Conventional 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

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).

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). / 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).