abstract: Membranes are a key part of pervaporation processes, which is generally a more efficient process for selective removal of alcohol from water than distillation. It is necessary that the membranes have high alcohol permeabilities and selectivities. Polydimethylsiloxane (PDMS) based mixed matrix membranes (MMMs) have demonstrated very promising results. Zeolitic imidazolate framework-71 (ZIF-71) demonstrated promising alcohol separation abilities. In this dissertation, we present fundamental studies on the synthesis of ZIF-71/PDMS MMMs. Free-standing ZIF-71/ PDMS membranes with 0, 5, 25 and 40 wt % ZIF-71 loadings were prepared and the pervaporation separation for ethanol and 1-butanol from water was measured. ZIF-71/PDMS MMMs were formed through addition cure and condensation cure methods. Addition cure method was not compatible with ZIF-71 resulting in membranes with poor mechanical properties, while the condensation cure method resulted in membranes with good mechanical properties. The 40 wt % ZIF-71 loading PDMS nanocomposite membranes achieved a maximum ethanol/water selectivity of 0.81 ± 0.04 selectivity and maximum 1-butnaol/water selectivity of 5.64 ± 0.15. The effects of synthesis time, temperature, and reactant ratio on ZIF-71 particle size and the effect of particle size on membrane performance were studied. Temperature had the greatest effect on ZIF-71 particle size as the synthesis temperature varied from - 20 to 35 ºC. The ZIF-71 synthesized had particle diameters ranging from 150 nm to 1 μm. ZIF-71 particle size is critical in ZIF-71/PDMS composite membrane performance for alcohol removal from water through pervaporation. The membranes made with micron sized ZIF-71 particles showed higher alcohol/water selectivity than those with smaller particles. Both alcohol and water permeability increased when larger sized ZIF- 71 particles were incorporated. ZIF-71 particles were modified with four ligands through solvent assisted linker exchange (SALE) method: benzimidazole (BIM), 5-methylbenzimidazole (MBIM), 5,6- dimethylbenzimidazole (DMBIM) and 4-Phenylimidazole (PI). The morphology of ZIF- 71 were maintained after the modification. ZIF-71/PDMS composite membranes with 25 wt% loading modified ZIF-71 particles were made for alcohol/water separation. Better particle dispersion in PDMS polymer matrix was observed with the ligand modified ZIFs. For both ethanol/water and 1-butanol/water separations, the alcohol permeability and alcohol/water selectivity were lowered after the ZIF-71 ligand exchange reaction. / Dissertation/Thesis / Doctoral Dissertation Chemical Engineering 2017

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P-xylene is one of the highly influential commodities in the petrochemical industry. It is used to make 90% of the world’s third largest plastic production, polyethylene terephthalate (PET). With a continuously increasing demand, the current technology’s high energy intensity has become a growing concern. Membrane separation technology is a potential low-energy alternative. Polymeric membranes were investigated in a pervaporation experiment to separate xylene isomers. Polymers of intrinsic microporosity (PIMs) as well as polyimides (PIM-PI), including thermally cross-linked PIM-1, PIM-6FDA-OH and thermally-rearranged PIM-6FDA-OH were investigated as potential candidates. Although they exhibited extremely high permeability to xylenes, selectivity towards p-xylene was poor. This was attributed to the polymers low chemical resistance which was apparent in their strong tendency to swell in xylenes. Consequently, a perfluoro-polymer, Teflon AF 2400, with a high chemical resistance was tested, which resulted in a slightly improved selectivity. A super acid sulfonated perfluoro-polymer (Nafion-H) was used as reactive membrane for xylenes isomerization. The membrane exhibited high catalytic activity, resulting in 19.5% p-xylene yield at 75ᵒC compared to 20% p-xylene yield at 450ᵒC in commercial fixed bed reactors. Nafion-H membrane outperforms the commercial technology with significant energy savings.

In this work polymeric materials were developed to be used as a solvent and heat resistance membrane for different applications. In ultrafiltration, poly (ether imide sulfone) membranes were manufactured by combining phase inversion and functionalization reaction between epoxy groups and amine modified polyether oligomers (Jeffamine®). Polysilsesquioxanes or oligo silsesquioxanes containing epoxy functionalities were in-situ grown in the casting solution and made available for further reaction with amines in the coagulation/annealing baths. Water permeances up to 1500 l m-2 h-1 bar-1 were obtained with sharp pore size distribution and a pore diameter peak at 66 nm, confirmed by porosimetry, allowing 99.2 % rejection of γ-globulin. The membranes were stable in 50:50 dimethylformamide/water, 50:50 N-methyl pyrrolidone/water and 100 % tetrahydrofuran. In pervaporation, Novel hydrophobic Hyflon®/Extem® and Hyflon®/PVDF were developed and investigated for ethylene glycol dehydration and n-butanol dehydration respectively. For ethylene glycol different Extem® concentrations were evaluated with regard to both flux and amount of water in the permeate side. Eighteen (18) wt% gave more than 90 wt% water in the permeate. Increasing feed temperature from 25 to 85°C increased the water flux from 31 to 91 g m-2 h-1 when using 5 wt% water in ethylene glycol as feed. The water flux of 40 wt% water:ethylene glycol at 45°C was found to be 350 g m-2 h-1. And for n-butanol dehydration the coating protocols for thin defect-free Hyflon® selective layer on the PVDF support was optimized. Water and n-butanol transport was measured, analyzing the effect of operating conditions. The water flux through the newly developed membranes was higher than 150 g m-2 h-1 with selectivity for water higher than 99 wt%. The membrane application can be extended to other solvents, supporting an effective and simple method for dehydration with hydrophobic membranes. In membrane distillation, PVDF and Extem® membranes before and after coating with Hyflon® were examined for ionic liquid dehydration on 23.6 mS cm-1 feed concentration. Different feed temperatures and flow rates were evaluated for flux as well as rejection. High flux was obtained at 70°C and increased at high flow rate from 2 Kg m2 h to 10 Kg m2 h.

L'objectif de ce travail est l'étude du procédé de pervaporation et plus particulièrement la compréhension des mécanismes de transfert de masse et de chaleur dans une membrane en polymère qualifiée de dense. Une meilleures compréhension des mécanismes permettrait de lever les verrous limitant le développement de ce procédé, comme les faibles flux de matière ainsi que l'origine et la quantité de chaleur nécessaire au transfert à travers la membrane. Pour cela, nous avons développé un dispositif expérimental qui permet de mesurer en simultané les densités de flux de matière et de chaleur. La configuration frontale statique de perméation du dispositif mis en place donne accès au profil de température du liquide d'alimentation. Ces données de température ont permis de calculer les densités de flux de chaleur engagées durant les expériences de pervaporation grâce à un calcul par méthode inverse couplé à une simulation STAR CCM+. La densité de flux de matière est mesurée par une nouvelle méthode. La nouvelle méthode utilise un capteur de pression situé dans le réservoir d'alimentation permettant de mesurer en continu la densité de flux de matière synchronisée avec la mesure des températures. Afin de simplifier au maximum les contraintes expérimentales, nous nous sommes restreints à la perméation de composés purs. La corrélation des deux flux mesurés nous a conduit à observer que la quantité de chaleur prise au fluide en amont pour pervaporer une unité de masse de liquide pur est inférieure à la quantité de chaleur nécessaire pour vaporiser ce même liquide. Elle représente 50 % de celle-ci dans le cas de l’eau et seulement 25 % dans le cas de l’éthanol. / The aim of this work is to study the pervaporation process and specifically to understand the mass and heat transport mechanisms in a dense polymeric membrane. A better understanding of these mechanisms would make it possible to improve the limiting parameters for the development of this process, such as the low mass fluxes as well as the origin and the quantity of heat required for transport through the membrane. In order to answer these questions, we have developed an experimental setup that allows simultaneous measurement of mass flux and heat flux density. The dead-end permeation of the setup developed gives access to the temperature profile of the liquid feed. These temperature data make possible the estimation of the heat flux densities engaged during the pervaporation experiments by means of an inverse computation coupled with a STAR CCM + simulation. The mass flux is measured by a new method in addition to the gravimetric method used as a reference. The new method uses a pressure sensor located in the feed tank to continuously measure the mass flux with 1Hz raw acquisition frequency synchronized with the temperature measurement. In order to simplify the experimental constraints, we applied only permeation of pure liquids. The correlation of the two fluxes (mass and heat density) measured led us to observe that the amount of heat taken to the feed side to pervaporate a unit mass of pure liquid is less than the amount of heat required to vaporize the same liquid. It represents 50% of it in the case of water and only 25% in the case of the ethanol.

This study was concerned with the recovery of aroma compounds from aqueous solutions by pervaporation using poly(ether-block-amide) (PEBA) membranes. Three model aroma compounds (i.e., propyl propionate, C6-aldehyde and benzaldehyde) were used in the study to represent ester, aldehyde and aromatic aroma compounds, respectively. The effects of process conditions (i.e., feed concentration and operating temperature) on the pervaporation performance (in terms of permeation flux and selectivity) for aroma-water separations were investigated. It was found that both the aroma permeation flux and the selectivity were affected significantly by the feed aroma concentration. The aroma permeability was in the order of propyl propionate > C6-aldehyde > benzaldehyde, and the membrane selectivity for aroma/water separation followed the order of C6-aldehyde > propyl propionate > benzaldehyde. In general, the aroma flux was found to be proportional to the aroma compound concentration in the solution. In the concentration range (390-3,200 ppm) tested, the effect of temperature on the permeation flux followed an Arrhenius type of relation. The solubility and diffusivity of the aroma compounds in PEBA membrane, which determine their permeabilities through the membrane, were determined from the pervaporation and sorption/desorption data. It was shown that the solubility of the aroma compounds in the PEBA membrane generally followed the Henry’s law where the sorption uptake was proportional to the feed aroma concentration. Among the three aroma compounds studied, benzaldehyde was found to have the highest solubility selectivity in the PEBA membrane, followed by C6-aldehyde and propyl propionate. The solubilities of pure propyl propionate and water in PEBA membrane were also estimated; the solubility of pure propyl propionate was around 130 times higher than that of pure water. This confirmed that PEBA was an excellent organophilic membrane. The diffusivity of the aroma compounds through PEBA membrane was affected by the feed aroma concentration. From steady state pervaporation and equilibrium sorption data, the diffusivity was calculated on the basis of solution-diffusion model, and the diffusivity was shown to be linearly dependent on the feed aroma concentration. On the other hand, from the sorption kinetics data obtained from the time-dependent sorption experiments, the diffusivity was shown to be affected by the feed aroma concentration exponentially. The main reason may be that the simple form of the solution-diffusion model is unable to precisely describe the mass transport through the membrane during pervaporation. As an alternative to pervaporation where the liquid feed is in contact with the membrane and the mass transport involves permeation and evaporation (thus the word “pervaporation”), evaporation-permeation (or evapermeation, where the feed liquid is not in direct contact with the membrane and the mass transfer involves evaporation and then permeation) was also studied for aroma compound separation from water. It was shown that evapermeation was no better than pervaporation in terms of permeation flux and selectivity. This again demonstrated that the state of the membrane and the location for liquid-vapor phase change were important to the mass transport through the membrane. For aroma recovery from dilute aqueous solutions, batch pervaporation is often preferred. Batch pervaporation coupled with permeate decantation and water phase recycle was studied parametrically. It was demonstrated that compared to the conventional pervaporation, the aroma recovery can be enhanced by recycling the water phase from the permeate decanter to the feed for further recovery. In addition, unlike the conventional batch operation where the product concentration starts to decrease beyond certain time, the modified batch pervaporation allows a longer period of operation without compromising the product purity.

This study was concerned with the recovery of aroma compounds from aqueous solutions by pervaporation using poly(ether-block-amide) (PEBA) membranes. Three model aroma compounds (i.e., propyl propionate, C6-aldehyde and benzaldehyde) were used in the study to represent ester, aldehyde and aromatic aroma compounds, respectively. The effects of process conditions (i.e., feed concentration and operating temperature) on the pervaporation performance (in terms of permeation flux and selectivity) for aroma-water separations were investigated. It was found that both the aroma permeation flux and the selectivity were affected significantly by the feed aroma concentration. The aroma permeability was in the order of propyl propionate > C6-aldehyde > benzaldehyde, and the membrane selectivity for aroma/water separation followed the order of C6-aldehyde > propyl propionate > benzaldehyde. In general, the aroma flux was found to be proportional to the aroma compound concentration in the solution. In the concentration range (390-3,200 ppm) tested, the effect of temperature on the permeation flux followed an Arrhenius type of relation. The solubility and diffusivity of the aroma compounds in PEBA membrane, which determine their permeabilities through the membrane, were determined from the pervaporation and sorption/desorption data. It was shown that the solubility of the aroma compounds in the PEBA membrane generally followed the Henry’s law where the sorption uptake was proportional to the feed aroma concentration. Among the three aroma compounds studied, benzaldehyde was found to have the highest solubility selectivity in the PEBA membrane, followed by C6-aldehyde and propyl propionate. The solubilities of pure propyl propionate and water in PEBA membrane were also estimated; the solubility of pure propyl propionate was around 130 times higher than that of pure water. This confirmed that PEBA was an excellent organophilic membrane. The diffusivity of the aroma compounds through PEBA membrane was affected by the feed aroma concentration. From steady state pervaporation and equilibrium sorption data, the diffusivity was calculated on the basis of solution-diffusion model, and the diffusivity was shown to be linearly dependent on the feed aroma concentration. On the other hand, from the sorption kinetics data obtained from the time-dependent sorption experiments, the diffusivity was shown to be affected by the feed aroma concentration exponentially. The main reason may be that the simple form of the solution-diffusion model is unable to precisely describe the mass transport through the membrane during pervaporation. As an alternative to pervaporation where the liquid feed is in contact with the membrane and the mass transport involves permeation and evaporation (thus the word “pervaporation”), evaporation-permeation (or evapermeation, where the feed liquid is not in direct contact with the membrane and the mass transfer involves evaporation and then permeation) was also studied for aroma compound separation from water. It was shown that evapermeation was no better than pervaporation in terms of permeation flux and selectivity. This again demonstrated that the state of the membrane and the location for liquid-vapor phase change were important to the mass transport through the membrane. For aroma recovery from dilute aqueous solutions, batch pervaporation is often preferred. Batch pervaporation coupled with permeate decantation and water phase recycle was studied parametrically. It was demonstrated that compared to the conventional pervaporation, the aroma recovery can be enhanced by recycling the water phase from the permeate decanter to the feed for further recovery. In addition, unlike the conventional batch operation where the product concentration starts to decrease beyond certain time, the modified batch pervaporation allows a longer period of operation without compromising the product purity.

Ethyl lactate is a promising, and environmentally benign chemical, which requires efficient separation techniques to overcome the equilibrium limitations in its production. Pervaporation based hybrid systems are successful in these type of equilibrium limited reactions, where product and/or by-product are removed from reaction medium by pervaporation unit(s) so as to drive reaction to completion. For the production of ethyl lactate four possible semi-batch hybrid systems were previously proposed. However, in order to select the suitable hybrid system within the proposed layouts phase equilibrium and reaction kinetics of the system must be well defined in addition to the performance data of the pervaporation membranes. Therefore, vapor pressure curve of ethyl lactate, VLE curves of ethanol-ethyl lactate and ethyl lactate-water were determined and performances of commercial hydrophobic membranes were investigated experimentally for the separation of ethanol-ethyl lactate mixtures. As a result of vapor pressure and VLE experiments, azeotrope was observed at 71wt% of water for ethyl lactate-water binary mixture at 80mmHg pressure. Furthermore, dependence of vapor composition on pressure was found to be slight for ethanol-ethyl lactate mixtures. Two commercial hydrophobic membranes, and an organoselective one were used in the separation of ethyl lactate-ethanol mixtures. It is found that hydrophobic membranes have sufficient fluxes and reasonable selectivities. Moreover, it is observed that as temperature increase flux increases and selectivity decreases. Finally, it is concluded that it would be possible to produce ethyl lactate by using the previously proposed integrated PV-esterification reactor systems.

Les nanoparticules (NPs) assemblées en architectures 2D ou 3D présentent de nouvelles propriétés optiques, magnétiques et électroniques collectives. Par exemple, des NPs d’argent (Ag) ou d’or (Au) absorbent la lumière à des longueurs d’onde plus grandes lorsqu’elles sont compactées que lorsqu’elles sont éloignées. Tout d'abord, des microparticules de latex et des NPs d’or sont assemblées par la technique de pervaporation microfluidique afin de former des matériaux denses aux dimensions contrôlées. En réduisant la concentration en sels contenus dans les dispersions de particules, ces dernières s’organisent en cristaux hexagonaux. Des matériaux millimétriques constitués de petites particules densément ordonnées sont collectés, offrant ainsi une base solide quant à la conception de nouveaux optomatériaux fonctionnels à l’échelle micrométrique. Ensuite, des NPs d’or et d’argent sont assemblées sur des gouttes d’émulsion afin de fabriquer des matériaux dispersés. En contrôlant les charges et la mouillabilité des particules, celles-ci s’adsorbent et se compactent en surface de gouttes. Les NPs sont ensuite fixées dans une écorce organique par une polymérisation à l’interface de l’émulsion. Dans des conditions bien définies, des microcapsules Au NP-silice et Au NP-polyacrylate respectivement sensibles aux déformations mécaniques et aux variations de pH sont obtenues. Ces microcapsules changent de couleur du fait de l’augmentation de la distance entre les Au NPs lors de la déformation des capsules. Chacune de ces microcapsules étant un capteur à elle toute seule, ces résultats ouvrent la voie vers la conception de nouveaux capteurs à l’échelle micrométrique. / Nanoparticles (NPs) assembled into two- or three-dimensional architectures offer new collective optical, magnetic and electronic properties. For instance, closely packed gold (Au) and silver (Ag) NPs absorb light at higher wavelength than when they are far apart. In the first part of this thesis, the technique of microfluidic pervaporation is used to assemble micron size latex particles and Au NPs in bulky materials of controlled dimensions. By reducing the concentration of salts in the particles dispersions, the particles organize in hexagonal crystals. Millimeter-long materials of small well-organized densely packed particles are collected, offering solid groundwork as for the design of new functional microscale optomaterials. In the second part of this thesis, the assembly of NPs on droplets is used to fabricate dispersed materials. By tuning the charges and wettability of Au and Ag NPs, they adsorb at the surface of emulsion droplets. A subsequent polymerization at the interface of the emulsion allows to lock the NPs inside an organic shell. In well-defined conditions, novel Au NP-silica microcapsules responsive to mechanical strains and Au NP-polyacrylate microcapsules responsive to pH variations are engineered. These microcapsules change color during their deformation due to the increase of the distance between the Au NPs. Each one of the microcapsules being one sensor by itself, these results pave the way as for the design of new microscale sensors.

L'acrylate d'éthyle est synthétisé par l'estérification catalytique de l'acide acrylique et de l'éthanol. La réaction s'écrit : CH2=CH-COOH + C2H5OH D CH2=CH-COOC2H5 + H2O Comme cette réaction est équilibrée, l'élimination de l'eau produit par la réaction permet de déplacer la réaction, donc d'augmenter le taux de conversion de l'acide acrylique et la productivité en acrylate d'éthyle. La pervaporation est une technique de séparation membranaire, qui est potentiellement intéressante pour la déshydratation de mélanges organiques. Dans ce travail, nous avons étudié le procédé industriel de l'estérification de l'acrylate d'éthyle qui est continu. C'est la première fois que la pervaporation d'un mélange complexe contenant des dérivés acryliques polymérisables est étudiée. Tout d'abord le procédé continu d'estérification a été simulé sur Aspen Plus. Une analyse du schéma de procédé a permis d'identifier deux scénarii d'amélioration des performances énergétiques par pervaporation. Dans le scénario le plus favorable, la pervaporation permet de réduire de 25% la consommation d'énergie ou d'augmenter de 25% la production. Dans la deuxième partie de notre étude, des membranes commerciales ont été testées pour déshydrater des mélanges représentatifs du milieu d'estérification. Les membranes testées ont montrées de bonnes performances de séparation (flux et sélectivité élevées) et de bonnes résistances chimiques. La faisabilité de l'intégration de la pervaporation au procédé est donc prouvée / Ethyl acrylate is synthesized by the catalytic esterification of acrylic acid and ethanol. The reaction can be described as: CH2=CH-COOH + C2H5OH D CH2=CH-COOC2H5 + H2O Since this reaction is reversible, the removal of the water helps shifting the reaction to the right side, thus increasing the conversion of acrylic acid to ethyl acrylate. Pervaporation is a membrane separation technique which is helpful for the dehydration of organic mixtures. In this work, we studied the industrial process for the esterification of ethyl acrylate which is continuous. To our knowledge this is the first time that the pervaporation of a mixture containing polymerizable acrylic derivatives is studied. Firstly, the continuous esterification process was simulated on Aspen Plus. An analysis of the flowsheet diagram has identified two scenarios for improving energy performance through implementing dehydration pervaporation. In the most favorable scenario, the pervaporation can reduce 25% energy consumption or increase 25% ethyl acrylate production. In the second part of our study, commercial membranes were tested for dehydrating mixtures which are representative of esterification reaction. The tested membranes offered good separation performance (high flux and selectivity) and high chemical resistance. The feasibility of the hybrid process is thus proven