Tesi sul tema "Solvant à eutectique profend"
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Mahi, Mohammed Ridha. "Captage du CO2 par des amines en milieu aqueux et non aqueux (solvant eutectique profond)". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1104.
This work focuses on the study of the absorption capacity of CO2 by different types of dissolved amines in aqueous and non-aqueous media. The latter consists of a mixture of choline chloride and ethylene glycol in a molar proportion of 1 to 2 respectively. This solvent, commonly called "Ethaline", belongs to the category called "Deep Eutectic Solvents" so designated because their eutectic composition makes it possible to obtain mixtures that are generally liquid at room temperature. With this aim, a liquid-vapor equilibrium apparatus with on-line analysis of the vapor phase by GC was performed and its operation validated. The CO2 absorption isotherms and the volatility (composition of the vapor phase) of the studied mixtures, with and without CO2, were determined at different temperatures and for different amine compositions. The explored pressure range is particularly large: from 1 Pa to 800 kPa. The study showed that the substitution of water by "Ethaline" leads to a CO2 absorption capacity almost identical to that of MEA and DEA in aqueous solution. On the other hand, in the case of MDEA, a lower absorption capacity is observed in Ethaline than in aqueous medium. In the hypothesis of a use of the DES+amine solvent for CO2 capture in post-combustion process, a decrease of the vapor pressure of the solvent (comparing to that of water+amine) has an advantage because of the low solvent loss due to vaporization in the absorber. The second advantage is most likely a lower effect of equipment corrosion, the third positive point is a lower enthalpy of absorption of MEA and MDEA in (1 ChCl : 2 EG) comparing to aqueous medium, resulting in a possible saving of energy in the regenerator of almost 40%. The disadvantage of the use of amines in "Ethaline" solution is the high viscosity of this solvent which decreases the kinetics of material transfer and reaction with CO2. The CO2 absorption isotherms and the experimental values of the amine volatilities in the different Amine-H2O-CO2 mixtures were well correlated by different semi-empirical models. Three thermodynamic models based on the activity coefficients; the Wilson model, NRTL and UNIQUAC were used to restitute experimental data for the liquid-vapor equilibrium of aqueous amine systems (without CO2). A satisfactory representation of the experimental results by the three models was obtained
Nessakh, Fatima Zohra. "Étude de nouveaux fluides de travail constitués de solvants à eutectique profond pour les pompes à chaleur". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0262.
A significant amount of waste heat is generated and rejected by industrial processes. This waste heat at low temperature can be upgraded using absorption heat transformers. Absorption heat thermo-transformers use conventional working fluids such as {water + lithium bromide} or {ammonia + water} systems. Nevertheless, the use of these working pairs in the processes has certain drawbacks such as corrosivity, toxicity or even crystallization. Other working fluids consisting of ionic liquid have also been considered. However, these solvents show significant toxicity and high costs. This study aims to evaluate the performance of working fluids consisting of a deep eutectic solvent (DES) and water in absorption heat thermo-transformers. The liquid-vapor equilibria of five {H2O + DES} systems as well as their thermophysical properties such as density, molar heat capacity and excess molar enthalpy were measured. This experimental work made it possible to develop empirical correlations and to adjust the parameters of the NRTL model in order to characterize the working fluids studied at any point of the absorption heat thermo-transformer. Simulations indicate that the working fluids {H2O + DES} have a performance close to {H2O + LiBr} mixture and they could be an alternative to traditional working fluids
Xie, Yuelin. "Electrodeposition of Co, Ni-based Alloys in Ionic Solutions and their Electrocatalytic Propert". Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS560.
The use of fossil energy, one of the main contributors to carbon emissions and a major source of pollution, has become a hot topic of discussion in recent years. Predicted energy shortages and the resulting environmental challenges are forcing mankind to look for alternatives to fossil fuels. Hydrogen is attracting increasing attention as a clean energy source, with high energy density and minimal emissions. It represents a promising, low-carbon energy carrier ready to supplant fossil fuels, particularly in the demanding industrial and transport sectors, where decarbonization is particular difficult to implement. According to existing literature, there are three main methods for producing hydrogen: hydrogen production from (i) fossil fuels, (ii) gasification, and (iii) water splitting. Water electrolysis under renewable resource conditions can practically eliminate carbon emissions, which is a significant difference compared to hydrogen production from fossil fuels (66 gCO2 e/MJ) or gasification (55 gCO2 e/MJ). Clearly, hydrogen production by electrolysis under ideal conditions has the distinct advantage of being environmentally friendly, with a low carbon footprint. Furthermore, water electrolysis offers many advantages, including the production of high-purity hydrogen, the simultaneous production of oxygen as a by-product, and simple installation. Although the hydrogen evolution reaction (HER) by water electrolysis provides numerous advantages for hydrogen production applications, its industrial adoption remains relatively limited, especially behind the production of hydrogen from fossil fuels. One of the main obstacles to its widespread use is the choice of electrocatalytic materials. Precious metals have exceptional electrocatalytic properties; however, their high cost and limited abundance on earth limit their practical application in all industries. Consequently, the search for cost-effective alternatives involving transition metals and the improvement of electrocatalyst performance through alloying and adjustments of surface morphology has emerged as important and dynamic lines of research. A wide range of techniques have been explored for synthesizing transition metal alloys used in electrocatalytic HER. Among these methods, electrodeposition stands out for its streamlined process, ease of implementation, and precise control, making it a versatile choice for large-scale applications. However, the hydrolysis of water during electrodeposition poses a problem. This can be effectively resolved by employing ionic liquids (ILs) as electrolytes, which are becoming increasingly popular due to their wide electrochemical window, high ionic conductivity, and user-friendly characteristics arising from their non-volatile and non-flammable nature. Surprisingly, research on the electrodeposition of alloys in ionic liquids remains relatively scarce. Consequently, combining the electrodeposition of alloy electrocatalysts with ionic liquids represents an attractive avenue to explore. In this work, we address the following questions: (1) Is it possible to prepare transition metal-based alloys by electrodeposition in ionic liquids? (2) What kinds of alloys can be prepared by electrodeposition in ionic liquids? (3) What is the impact of other elements (Co, Zn, Cu) on the HER properties of alloys? (4) How can the HER properties of alloys be enhanced by surface modification (dealloying)?
Longeras, Olympe. "Design et compréhension de nouveaux solvants eutectiques profonds". Thesis, Université Clermont Auvergne (2017-2020), 2020. http://www.theses.fr/2020CLFAC048.
Deep Eutectics Solvents (DES) is a new class of solvent which has emerged during the last decades. DES have been increasingly studied because of their low cost and low toxicity. Because of these properties, DES could potentially replace toxic solvents used in large area of chemistry. To reach this goal, a broader knowledge of these new systems has to be acquired. Therefore, in the first work of this thesis, solid-liquid phase diagrams of three partially renewable DES have been established. The comparison of these diagrams to an ideal mixing model is showing a negative deviation that allows to considered them as “deep” eutectics solvents. Following this work on the binary mixture, water was added to these DES. A first aqueous - DES mixture with a lower critical solution temperature (LSCT) has been highlighted and the origin of this remarkable property has been elucidated. To complete the initial work aiming to get a deeper understanding of these new DES, these solvents have also been tested for two applications: carbon dioxide capture and liquid-liquid extractions of dyes
Cablé, Pierre-Alann. "Étude de solvants à eutectique profond pour l'extraction de molécules à haute-valeur ajoutée issues de la biomasse ligno-cellulosique". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0298.
Lignocellulosic biomass (wood, wastes, algae etc.) is one of the most important renewable carbon sources. Its valorisation into fuels, chemicals and materials can lead to climate change mitigation. Nevertheless, scientific challenges remain unravelled for efficient biomass valorisation in biorefineries. A new family of sustainable solvent, deep eutectic solvents (DESs) are promising option for biorefineries development: 1) High-added value compounds extraction after thermochemical conversion (HydroThermal Liquefaction, HTL) 2) Ligno-cellulosic biomass pre-treatment (delignification process). This work shows the efficiency of DESs to extract phenolic compounds (PCs) from various media using liquid-liquid extraction. Quantum chemistry calculation show that PCs have a stronger affinity with DESs than water. These results agree well with experimental study while DESs allow to extract more than 80 % of PCs from model oil. Moreover, DESs show higher efficiency in comparison with ionic liquid(5 times) and similar efficiency than conventional solvents used in liquid-liquid extraction. Nevertheless, DES appear to be ineffective for the PCs extraction from liquid products of beechwood hydrothermal conversion. Nonetheless, the used of acid-DESs such as Choline chloride: oxalic acid for biomass pre-treatment seems to be a promising application. 50 %wt delignification yield has been obtained during beechwood pre-treatment. A selective cleavage of lignin and hemicelluloses without affecting cellulose and with ether linkages preservation. This successful separation allows the valorisation of each component of biomass
Kern, Barreto Cynara Caroline. "Dispersão de nanopartículas magnéticas em meios complexos biodegradáveis". Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066419/document.
Magnetic nanocolloids are dispersions of magnetic nanostructures in a carrier fluid. Thanks to the original properties of both the liquid and the magnetic particles, these dispersions can be confined, moved, deformed and controlled by applying an external magnetic field. Such dispersions thus have many applications in nanoscience and nanotechnologies.We studied the dispersion of magnetic nanoparticles in deep eutectic solvents (DES). These solvents (DES), obtained by mixing a quaternary ammonium salt (e.g., choline chloride Ch) and a hydrogen bond donor (e.g., ethyleneglycol EG or Urea U) have properties similar to ionic liquids, and are also biodegradable. One of the questions about these dispersions is the nature of the forces implied in colloidal stability, since the DLVO model classically used in water cannot be invoked here due to the very high ionic strength of the solvent.In a first step, we have carefully characterized two DES ((ChEG (1:3) and ChU (1:2) in mol), measuring the density and viscosity for temperatures between 20 and 45°C. We could thus show the high association in these liquids.A protocol to disperse nanoparticles of maghemite (Fe2O3) or mixed ferrite (CoxZn1-xFe2O4) is then proposed, and the obtained dispersions are studied by dynamic light scattering and SAXS. The size polydispersity was reduced by size sorting, and it reveals that the smallest particles are the most easy to disperse in the DES.Last, a synthesis of NMP in clay dispersion was tested and showed promising results with a reduced size polydispersity
Beliaeva, Kristina. "Captage et conversion électrochimique du CO2 dans des liquides ioniques et des solvants eutectiques profonds avec des catalyseurs à base de Pd". Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALI094.
Carbon dioxide capture and utilization (CCU) is a way to decarbonize industrial sector. This technology provides a valorization of cheap carbon feedstock by its transformation to carbonaceous value-added chemicals. Multiple CO2 capture and utilization techniques exist to prevent the release of the greenhouse gas to the atmosphere. Here, we propose an integrated process of CO2 capture sequenced by electroconversion to C-based products in electrochemical cell. Electrochemical CO2 conversion is a promising method due to mild reaction conditions and possibility to power the reaction with electricity produced by renewable energy sources. This process necessitates the development of solvents capable to capture CO2 and to play a role of electrolyte during electrochemical reduction reaction. At the same time, efficient catalytic materials are vital for selective CO2 conversion to targeted product(s). The choice of capture solvent is usually based on CO2 capture ability, chemical and electrochemical stabilities, environmental issue and cost. Economically affordable deep eutectic solvent (DES) electrolytes seem to be promising candidates for CO2 capture and electroreduction because of good thermal and electrochemical stabilities, competitive CO2 uptake and large electrochemical windows. In this work, we focused on the development of novel deep eutectic solvent electrolytes for CO2 electroreduction with Pd-based electrocatalysts. Palladium proved its efficiency for selective conversion of carbon dioxide to C1 molecules such as carbon monoxide.During the thesis, we synthesized and electrochemically tested multiple DESs and Pd-based electrocatalysts with different morphologies and particle sizes to get more insights into reaction mechanism of CO2 electroreduction to C1 molecules. The implementation of different characterization techniques helped to study catalytic materials and DESs structures, to analyze gaseous and liquid reaction intermediates and products, and to understand main challenges of the studied system. Overall, this study is a one step forward the application of CO2ER (carbon dioxide electrochemical reduction) for valorisation of carbon dioxide and climate change mitigation
Moufawad, Tarek. "Développement de nouveaux solvants de lavage pour l'absorption des Composés Organiques Volatils". Thesis, Littoral, 2019. http://www.theses.fr/2019DUNK0534.
The aim of this thesis was to develop new solvents for the absorption of volatile organic compounds (VOC). VOC are primary air pollutants generally used as solvents and emitted directly from industries. They have adverse health effects and some of them are classified as carcinogenic. Consequently, the reduction of the emissions of these pollutants remains a major challenge to reduce air pollution. Hence, our objective was to evaluate deep eutectic solvants (DES) as absorbents for VOCs. DESs represent a new generation of solvents that is formed by simply mixing two or more compounds. They can be produced from cheap, natural and biodegradable compounds. The preparation of these solvents is easy and is 100% atom efficient. This work was divided into three parts.The first part focused on the physicochemical properties of DES, such as density and viscosity. Analysis of the infrared spectra of DES and their pure compounds showed that hydrogen bonds are essential for the formation of DES. Their polarity was studied using the Nile red probe. In addition, solubility of various gases (CO₂, CH₄ and Ar) was measured as a function of temperature. The second part dealt with the evaluation of the aborsption capacity of DESs using static headspace coupled with gas chromatography. The determination of gas/liquid partition coefficient was performed for various VOC and DES at different temperatures. In addition, the influence of VOC mixtures on DES absorption capacities was determined. DES showed high absorption capacities for a variety of VOCs, without saturation even at high concentration. A new DES-cyclodextrin system was developed and showed improved absorption capacities due to the complexation ability of the cyclodextrin. The last part was oriented towards the industrial application of DESs. The absorption capacities of DESs were evaluated using a dynamic set-up which simulated an industrial absorption column. This set-up allows the modulation of the VOC flow rate, water content and column temperature. Finally, the regeneration of the absorbent was carried out by several absorption/desorption cycles without loss of absorption capacity. In conclusion, the overall results showed that DES have characteristics that allow them to be considered as promising solvents for VOC absorption
Rayee, Quentin. "Dépôts électrochimiques d’argent, de palladium et d’alliages argent-palladium en solvants eutectiques profonds". Doctoral thesis, Universite Libre de Bruxelles, 2020. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/303218.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Durand, Erwann. "Solvants de type eutectiques profonds : nouveaux milieux réactionnels aux réactions de lipophilisation biocatalysées par les lipases ?" Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20138/document.
With the emergence of the green chemistry concept in the 90s, many studies have been dedicated to the discovery of new reactions media both suitable and efficient for chemical/enzyme catalysis. Up to now, the main efforts have focused on the development of ionic liquids. However, recently a novel class of solvent called "deep eutectic mixtures (DES)", have been described as a serious alternative and economically stronger than ionic liquids. Such solvents are formed by mixing an organic salt (ammonium or phosphonium) with a hydrogen-bond donor. Just like ionic liquid, DES may also be liquid at room temperature, non-volatile and have excellent thermal stability. However, unlike most ionic liquids, these new solvents are biodegradable, inexpensive, and very easy to prepare. In the field of biocatalysis, whereas the studies in ionic liquid are deeply documented, the published papers describing biotransformation reactions in DES are very low, especially in lipase-catalyzed processing, where these enzymes may be used in so-called "lipophilisation reactions", for the synthesis of new molecules with high added value (surfactants or lipophilized antioxidants).The main objective of this work was to assess and test the potential of DES as new "green" reaction media for lipase-catalyzed synthesis. On a fundamental point of view, this study provides valuable information to understand how the different components involved in these mixtures could contribute to their functional properties in order to enhance their use in various applications. Changes in reaction conditions (solvents and biocatalysts) allowed us to highlight the clear superiority of two DES (chloride cholinium:Urea and chloride cholinium:glycerol) to carry out lipase-catalyzed reactions using the lipase B from Candida antarctica as biocatalyst. However, our results showed that the biotransformations of dissolved substrates (such as phenolic compounds) in DES are extremely difficult to achieve without the addition of water. Studying DES-water mixtures (pH, thermodynamic activity of water, activity and stability of lipase, mixtures composition, etc ...) we were able to fine-tune the reaction conditions to optimize the performance of the lipasic catalysis. Thus, given the difficulties encountered when performing lipase-catalyzed reactions with substrates of two different polarities, it was still possible to synthesize high yields of a full range of lipophilic derivatives of ferulic and coumaric acids from C4 to C16 (aliphatic chain)
Koumba, Ibinga Sidrine Kerthy. "Coupure de liaisons glycosidiques de la biomasse saccharifère couplée à la formation de liaisons esters amphiphiles". Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0062.
In 2030, vegetal-based chemistry will occupy 30% of total chemistry in France. Bioresources offer the opportunity to substitute products from petrochemicals. With a stable penetration rate of 25- 30% according to ADEME forecasts, biosurfactants are a way of adding value to agricultural products. The lipophilic and hydrophilic sources needed to obtain these amphiphilic compounds can be completely natural. Thus, the chia seed of the Oruro® variety has been used as a source of the hydrophilic part represented by the mucilage. The surface mucilage of the seed of this variety domesticated in France is made up of polysaccharides, proteins and minerals. It can be extracted effectively by ultrasonic cavitation in aqueous media. The composition and properties of the mucilage are related to the extraction time. This mucilage constitutes a hydrophilic source for obtaining amphiphilic esters. The lipophilic source chosen is the Irvingia gabonensis almond from a variety rich in high myristic (51%) and lauric (38%) butter. The triglycerides of this butter are made up of mixtures of saturated fatty acids. They are good candidates for food, nutrition and also industry and production of technofunctional biosurfactants. The work is therefore aimed at the simultaneous valorization of the mucilage and oil of I. gabonensis by the synthesis of biosurfactants. Two synthesis routes for obtaining amphiphilic esters have been explored. The first pathway involved the implementation of the transesterification reaction between glucose and methyl laurate in a deep eutectic medium DES Choline chloride/glucose. The second pathway involved acid catalysis in an organized medium by the implementation of the esterification reaction of glucose or mucilage with lauric C12:0 and myristic C14:0 fatty acids in the presence of dodecylbenzene sulfonic acid (DBSA). The studies of the esterification reactions were previously carried out using glucose and then transferred to mucilage. The use of DBSA with a dual role as a Brönsted catalyst and surfactant promotes the contact of the reagents, catalyzes the esterification reaction between the hydroxyl groups of glucose or polysaccharides and the carboxylic groups of the C12:0 lauric and C14:0 myristic fatty acids and therefore allows the glucose esters of degree of substitution DS=1-2 to be obtained. The surfaceactive and emulsifying properties of these glucose esters are comparable to those of a commercial Olivem 1000 ester, a mixture of sorbitan olivate and cetearyl olivate. The reaction between chia Oruro® mucilage and the fatty acid mixture of I. gabonensis in the presence of ADBS resulted in a profound structural modification of the biopolymer. Its lipophilization is obtained by the double monoacylation of the hydroxyl sites of the mucilage by the mixture of lauric C12:0 and myristic C14:0 fatty acids. The intrinsic viscosity of the acylated mucilage is very low (6.34 dL/g) compared to that of the crude mucilage (36.18 dL/g) used as starting reagent. This results in a profound change in the techno-functional properties of the acylated mucilage
Villemejeanne, Benoît. "Étude des milieux liquides ioniques et solvants eutectiques profonds pour une valorisation des métaux critiques à partir des déchets d’équipements électriques et électroniques". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0010.
The growing increase of waste electrical and electronic equipments (WEEE) on Earth, associated with their high metal contents are driving academic or industrial international researchers to develop their recycling and in particular the recovery of the metal fraction they contain. The treatment of these complex materials (polymetallic, composites, etc.) is based on several successive stages including pyrometallurgical or hydrometallurgical processes that do not follow Green Chemistry principles (waste generation, worker safety). Indeed, concentrated acidic solutions or toxic reagents such as cyanides are necessary to recover pure noble metals such as gold (Au) or palladium (Pd). This PhD work aims to break with the conventional chemistry practiced for over a century in the field of extractive metallurgy with the using of new kind of solvents: ionic liquids (IL) and deep eutectic solvents (DES). The combination of these solvents with electrochemical techniques allows implementing an ElectroLixiviation-ElectroChemical Deposition process (EL-ECD) with waste dissolution at the anode and the simultaneous recovery of the target metal at the cathode without any solvent degradation. A screening was carried out to understand the impact of the nature of ionic solvents on precious metal oxidation properties and mass transport properties (viscosity, ionic conductivity). Among many electrolytes, Ethaline (ChCl:EG 1:2) and imidazolium-based ionic liquid mixtures C4C1Im (NTf2)1-xClx, present interesting properties for the aimed application. A proof of concept and an optimization of this process for Au and Pd recovery in a monometallic medium in ChCl:EG mixtures was carried out. Faradic yield and recovery rate reached are suitable for an application in small WEEE treatment units
Di, Pietro Thomas. "Approche multi-échelle pour la modélisation de fluides de travail des procédés de revalorisation de la chaleur fatale". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0184.
Industries produce a significant amount of waste heat usually rejected in the atmosphere. As of today, it is possible to produce high temperature heat (120-150°C) from medium temperature heat (60-80°C) by using a particular kind of absorption heat pumps: the absorption heat transformers (PACA type II or AHT). Unfortunately, traditional working fluids (water/lithium bromide or ammonia/water) display numerous drawbacks (corrosion, toxicity, risk of crystallization…) which hinder the development of these technologies.This study focuses on the working fluids water/deep eutectic solvents (DESs) as a green and cheap solution of replacement. Using an innovative method based on a multiscale approach, this work aims at modelling the properties of many DESs without the need of a comprehensive and costly experimental investigation. At first, quantum chemical calculations were performed in order to get a better understanding of the molecular structure of different components of working fluids and the interactions between them. The importance of the hydrogen bond between the chloride ion and the hydroxyl groups has been highlighted in the most stable conformations of the DESs {choline chloride : phenol} and {choline chloride : glycolic acid}. From these observations, a modified version of the COSMO-SAC (COnductor-like Screening MOdel segment activity coefficient) model taking into account the possible hydrogen bonds between atoms of chlorine or bromine and hydroxyl groups was developed. This model improves the prediction of the vapour-liquid equilibria of mixtures with chlorine and bromine atoms, including DESs. Group contribution models have also been developed to predict three key properties of DESs: the density, the viscosity and the heat capacity.These models have been implemented in a simulation tool to evaluate the performances of 32 water/DES working fluids in AHT. Their performances are close to those of the traditional working fluids
Bessière, Guillaume. "Élaboration de matériaux carbonés par carbonisation eutecticothermale". Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2343.
This thesis works deal with the applications of green chemistry concepts for carboneous material preparation. Indeed, carboneous materials are used in many domains and the current environmental concerns engender a growing interest for sustainable carbons.So, we chose to apply the parameters of hydrothermal synthesis (which are widely used for materials preparations) for new types of compounds: the deep eutectic solvents. They are made from a mixture of fructose and choline chloride. This new synthesis is named “eutecticothermal carbonization”. This kind of synthesis allows using non toxic and sustainable precursors and avoids solvent using. The so obtained materials are the same characteristics as hydrothermal ones but the supramolecular network of the eutectic engenders morphological differences. Furthermore some non-negligible nitrogen quantities (4.82 w% for polymers and 0.62 w% for carbons) are incorporated in these solids by choline encapsulation. Indeed a mechanical study shows the important effect of this one, according to its proportions in the initial mixture, on the dehydratation/polycondensation reaction taking place during the materials formation. So it is for the mixtures containing between 50 and 80 w% of fructose that this effect is increase. Finally, theses materials shows good results in acid catalysis and CO2 adsorption applications
El, Achkar Tracy. "Deep eutectic solvents : characterization, interaction with synthetic and biological membranes, and solubilization of bioactive volatile compounds". Thesis, Littoral, 2020. http://www.theses.fr/2020DUNK0562.
Deep eutectic solvents (DES) recently emerged as a novel class of green solvents with a high potential to replace common organic solvents. Despite their novelty, DES were extensively explored in the past years owing to their remarkably interesting properties. Yet, a lot remains to be uncovered given the limitless number of possible DES and their versatility. The current sudy aimed to examine the effect of DES on liposomes, adopted as model membranes, and on cell membranes. It also sought to evaluate the solubilizing ability of DES toward bbioactive volatile compounds. Therefore, a group of selected DES along with new solvents were first prepared and characterized. Density, viscosity and polarity measurements were mainly carried out and showed that DES' properties can be tuned depending on their composition. The organization of phospholipids and liposomes within the DES was then investigated using optical- and atomical force microscopies. Phospholipids self-assembled into vesicles in choline chloride-based DES while liposomes converted to lipid bilayers before their reconstitution into vesicles. Moreover, cytotoxicity studies and morphological examinations were combined to evaluate the impact of some DES on MDA-MB-231, a human breast cancer cell line. Results showed that the effect is highly dependent on the DES' composition. On the other hand, the solubilizing ability of the DES toward bioactive volatile compounds was tested using static headspace-gas chromatography. The influence of the presence of water and some encapsulation systems such as liposomes and cyclodextrins on the overall DES' solubilization efficiency was further analyzed. At last, the release of trans-anethole from the DES was monitored via multiple headspace extraction. DES were able to greatly solubilize the bioactive volatile compounds and to control their release when compared with water. Altogether, this work highlights the potential use of the DES-based systems as solubilization vehicles for bioactive compounds
Carvalho, villarim Pedro. "New compacts systems for biogas upgrading". Electronic Thesis or Diss., Littoral, 2023. http://www.theses.fr/2023DUNK0697.
Biogas is a renewable energy source produced naturally by the anaerobic digestion of organic matter. It consists mainly of methane (CH4) and carbon dioxide (CO2). It also contains traces of water vapour, volatile organic compounds (VOCs) and hydrogen sulphide. Biogas upgrading to biomethane requires the removal of contaminants in the raw biogas, reducing the level of impurities to achieve high CH4 content of about 90 to 99%. The uses of biomethane are the same as natural gas while being a 100% renewable and non-fossil energy source. Many technologies have been tested and applied to remove impurities from biogas, such as water scrubbing, physical and chemical scrubbing, membrane separation, pressure swing adsorption, biological methods, etc. Absorbents play an important role in removing impurities from biogas. Therefore, the development of novel absorbents with high absorption capacity and high recyclability is mandatory. The suitable absorbent should also have low viscosity, relatively low toxicity, low vapor pressure, high boiling point, high absorption capacity, and low cost. Deep eutectic solvents (DESs) are a mixture of two or three chemical compounds (usually a hydrogen acceptor compound, HBA and a compound hydrogen donor, HBD), which combine via hydrogen bonds that have a lower melting point than each of their pure components. These solvents have physico-chemical properties that can be tuned depending on the nature of the individual compounds and their ratio. The purpose of the thesis was to evaluate DESs and conventional green solvents as VOCs/CO2 absorbers for biogas upgrading. We evaluated and compared the efficiency of different DESs and conventional absorbents for the absorption of nine VOCs and CO2. The vapor–liquid partition coefficient (K) of the VOCs in the studied solvents and the absorption capacity of CO2 in DES were determined using static headspace-gas chromatography. The effect of VOC mixture, temperature water content was evaluated. The absorption capacities of individuals VOCs, their mixture and CO2/CH4 in DESs and conventional solvents were also evaluated using a dynamic set-up which simulated an industrial absorption column. Both static and dynamic results are in good agreement. Also, the absorption capacities of industrial absorbents were evaluated on an industrial scale using an exchanger developed by our industrial partner (Terrao®)