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The Application of Sulfonated Poly(arylene ether)s for Proton Exchange MembraneHo, Chi-Jen 06 July 2011 (has links)
Three aromatic poly(arylene ether)s P2¡BP3¡BP4 were synthesized from bis(fluoride)4,4¡¨¡¨-Difluoro-3,3¡¨¡¨-bsi-trifluoromethyl-n¡¨-bisphenyl-[1,1¡¦;4¡¦,1¡¨;4¡¨,1¡¨¡¦;4¡¨¡¦,1¡¨¡¨]-quinquephenyl(n¡¨:2¡¨,3¡¨[G2];2¡¨,3¡¨,5¡¨[G3];2¡¨,3¡¨,5¡¨,6¡¨[G4]) with 4,4'-(9-Fluorenylidene)diphenol. The molecular weight of the polymer (Mw: 105-1.6¡Ñ105, PDI:1.5-2.2) was measured by gel permeation chromatography and the structure was confirmed by NMR spectra. Thermal stability was measured using Thermogravimetry and Thermomechanical Analysis. The polymer had a Td at 520¢J ~550¢J, and soft point at 310¢J. Young's modulus of polymer was (1.25-2.5Gpa). This polymer has high strength, modulus of elasticity, and thermal stability. The polymer consists of polyaromatic groups with bisfluoride monomer, (5, 6, 7 aromatic). We hypothesized that sulfonation of the polymer will exhibit high conductivity and great mechanical properties. Ion exchange capacities (IECs) were evaluated by acid¡Vbase titration. We sulfonated the polymer in order to apply to the proton exchange membrane fuel cell. The results showed after sulfonation of P4, IEC is 3.3(meq/g), and sulfonation of P2 showed that its proton conductivity is 75% more than Nafion117 at 80¢J with 0.28(S/cm).
Keywords: proton exchange membrane, proton conductivity, Nafion, sulfonated, ion exchange capacity
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Compréhension par établissement de courbes d'étalonnage de la structure des membranes perfluorées sulfoniques pour pile à combustible / Understanding of the structure of perfluorinated sulfonic membranes for fuel cellMoukheiber, Eddy 05 July 2011 (has links)
Ce travail de thèse a pour but l’étude des effets de la contamination cationique sur lamembrane électrolyte afin d’élaborer des outils de caractérisation et de diagnostic de cette pollution.Premièrement, la caractérisation physico-chimique de membranes PFSA commerciales arévélé des paramètres pertinents de structure et de propriété, qui ont été étudiés en fonction de leurdépendance à la capacité d’échange ionique (IEC).Deuxièmement, les propriétés thermiques des membranes contaminées par des cations ontrévélé des changements dépendant fortement de l’acidité de Lewis du cation (LAS). Cette tendance aété corrélée à la nature de l’interaction des différents cations avec les groupements polaires de lachaîne polymère, révélée par FTIR.Enfin, l’influence du taux de pollution sur les différents paramètres thermiques et structurauxnous a permis de révéler ceux qui sont pertinents non seulement à l’identification mais aussi à laquantification de la pollution. Une application des courbes d’étalonnage a été réalisée sur desmembranes vieillies issues de systèmes réels après fonctionnement. / The purpose of this study was to experimentally determine the effects of cationiccontamination on PEMFC ionomers in order to elaborate characterization tools and new modes forpollution diagnosis.First, a large series of techniques were used to investigate the properties of commercial PFSAmembranes. Distinctive parameters concerning structure and properties were extracted as well as theirrelationship to ion exchange capacity (IEC).Second, the thermal properties of cation-contaminated membranes revealed changes that arehighly dependent on the Lewis Acid Strength of the cation (LAS). This trend was correlated with thenature of the interaction between the cations and the polar groups of the polymer chain, revealed byFTIR spectroscopy.Finally, the influence of the pollution level on the thermal and structural parameters allowedus to reveal not only the relevant parameters to the identification but also to the quantification ofpollution. An application of the different calibration curves was performed on aged membranescoming from real operating systems.
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Vliv technologie kompostování v městské kompostárně na kvalitu produktuBARTUNĚK, David January 2017 (has links)
The thesis is about the processing of biological waste in the Czech composting plants with focus on the quality of the final compost. In 2016, there was more than 160 composting plants in the Czech Republic. The thesis is focused on the most widely used technologies in small composting plants in terms of their impact to the quality of the final product, including the follow-up of individual indicators during composting. The best technology in my work is based on a higher decomposition temperature (85 ° C) at the first stage of composting. The practical part of thesis is focused on the measurement of ion-exchange capacity according to Sandhof as a main material for the overall evaluation of the functionality of composting. The final value shows the compost quality of the individual composting plants in terms of ion exchange flexibility of the produced substrate. The best result was achieved with the combination of composting boxes and composting in the belt heaps. The value of the ion-exchange capacity with the best technology was 52.8 mval .100 g of the soil, with 77.9% of the distributed biowaste. You have to expect with an average annual costs of composting about 1,696,000 crounds in the Czech republic, when you are designing small functional composting plant with production of 2000 tons of the compost per year.
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Synthesis and Characterization of Sulfonated Polyimides as Proton Exchange Membranes for Fuel CellsGunduz, Nazan 26 April 2001 (has links)
Series of homo- and copolyimides containing controlled degrees of sulfonic acid ion conducting pendant groups have been synthesized from both phthalic (five-) and naphthalic (six-membered) dianhydrides and appropriate wholly aromatic diamines and heterocyclic analogues. The goal is to identify thermally and hydrolytically stable ion conducting polymers (ICP) suitable as proton exchange membranes, PEM, for fuel cells. The candidate ICP's have been synthesized and characterized for molecular weight, chemical composition, film forming properties, thermal transition behavior, boiling water stability, solvent solubility and water absorption and conductivity.
Commercially available five-membered ring dianhydrides such as 6FDA, BPDA, and six-membered ring dianhydrides such as naphthalene tetracarboxylic dianhydride (NDA) have been used. High molecular weight five-membered ring polyimides were obtained from an equimolar ratio of diamines and dianhydride using a one-pot ester-acid procedure by initially converting the dianhydride to a diester-diacid derivative, followed by the reaction with sulfonated and unsulfonated aryl diamines. The sulfonated diamine monomer was allowed to oligomerize with the diester-diacid of the dianhydride for 2-3 hours, before unsulfonated diamine was charged into the reaction flask. The levels of sulfonation in the polymer backbones were controlled by varying the mole ratio of sulfonated diamine to unsulfonated diamine.
For the six-membered ring polyimides, phenolic solvents, e.g. m-cresol, have been used. In general, 4,4′-diamino-biphenyl-2,2′-disulfonic acid (DPS) has been employed as the source of the sulfonated unit. The chemical compositions of both sulfonated and unsulfonated polyimides were obtained using ¹H-NMR and FT-IR. The sulfonic acid contents in both diamine monomers, as well as the sulfonated polyimides were also analyzed by acid-base potentiometric titration.
In all cases, high inherent viscosity values and good film forming ability of the polymers were the key indications of high molecular weight. The viscosity values increased with an increase of sulfonation degree in the polymers. This increase of viscosity in these ionomers can be attributed to the increase of polymer chain aggregation with their increasing ionic character.
Polymers were fabricated into membranes via solution casting or spin casting from DMAc or m-cresol in order to study film-forming properties. The solution cast dry films of the sulfonated polyimide membranes gave tough, ductile membranes and demonstrated moderate to high water absorption, which is necessary for PEM fuel cells. However, swollen films, in general, showed poor hydrolytic stability which resulted in brittle membranes.
The solution-cast membranes were thermally analyzed to study the effect of the degree of sulfonation on the thermal properties of sulfonated polymers. All the thermograms of the sulfonated polyimide films exhibited a two-step degradation behavior. The first weight loss, observed between 300-400 °C, corresponds to desulfonation in the sulfonated block, and the second weight loss, observed for a temperature around 500 °C or above, corresponds to the polymer backbone degradation. The TGA thermograms indicated that the initial weight losses were steeper for polymers with higher sulfonation degrees. Furthermore, the weight loss temperature of sulfonated polyimides decreased and broadened with increasing sulfonation levels. However, the onset temperature of the first weight loss was independent of the degree of sulfonation. Weight loss data in TGA curves of the sulfonated polymers were used to calculate the degree of sulfonation. Experimental and theoretical values were in good agreement with each other.
The sulfonated five-membered polyimide membranes were aged in an air-oven at increasing temperatures (30-220 °C) for 30 min and then titrated with TMAH using non-aqueous potentiometric titration. All the films that were aged up to 220 °C were still completely soluble in DMAc. Moreover, the sulfonic acid groups were unchanged.
In addition, several new flexible sulfonated and unsulfonated diamines and bis(naphthalic anhydride) monomers containing phosphineoxide [-P(O)-] or sulfone [-S(O)₂ -] moieties in their structure have been synthesized and characterized with various analytical techniques. The structural design of naphthalic polyimides by incorporating bis(naphthalic anhydrides) was one approach to give a better solubility and processability of their related products.
Development of an iterative approach for defining the optimum degree of sulfonation that will produce the highest ionic conductivity while still retaining other important properties such as flexibility, strength, hydrolytic stability has been a goal of this research and will be discussed in the thesis. / Ph. D.
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Ion exchange equilibrium: selectivity coefficient and ion exchange capacity, heavy metals removal, and mathematical modellingCaluori, Maryanne January 2020 (has links)
This research conducted equilibrium experiments to determine ion exchange equilibria data for the inorganic cations Ca2+, Na+, and NH4+ for binary cation exchange involving sulfonic acid, polystyrene gel resins saturated with Na+ or NH4+. A linear least-square fitting was developed to find representative ion exchange capacity (IEC) and selectivity coefficient (K) values. Equilibrium experiments were utilized to test the developed new linearization method for binary systems: Ca-NH4; Ca-Na; and Na-NH4 using three commercial strong acid cation (SAC) exchange resins. It was determined that SAC exchange resins saturated with NH4+ were more selective towards Ca2+ than resins saturated with Na+. The valency and the size of the hydrated radius of the counterion influenced the selectivity of binary systems. A higher valence and a smaller hydrated radius resulted in an increased affinity of the resin for ions. Results can be used to estimate the technical and economic feasibility of a design process along with the estimation of the effect of a change in operating conditions. In addition, the removal of toxic heavy metals was also investigated with an initial metal concentration of 0.1 mg/L. Results showed that the maximum percent removal of toxic heavy metal ions, Cr3+, Pb2+, Ba2+, and Cd2+ ranged from ~ 95-99% when present in a solution containing a high molar concentration of Ca2+, Na+, and NH4+. It was observed that SAC exchange resins can effectively remove toxic heavy metals at very low concentrations. The high selectivity that SAC exchange resins possess towards heavy metals proves that they can be used as a pretreatment method for the removal of toxic heavy metals from municipal and industrial wastewaters. Moreover, the performance of SAC exchange resins for the removal of Ca2+ from waste solutions was investigated through computer modelling. Results showed that ion exchange is an efficient method for the removal of Ca2+. A sensitivity analysis showed that the variation in K and IEC greatly influenced the breakthrough time as an increase in both parameters resulted in greater Ca2+ uptake. Modelling results can be used to optimize the design of ion exchange systems for the pretreatment of inorganic cations which can reduce membrane scaling. / Thesis / Master of Applied Science (MASc)
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Analýza půdní organické hmoty v kambizemi modální po šesti letech každoročního hnojení zemědělským a komunálním kompostemBROUČKOVÁ, Vlasta January 2017 (has links)
Organically overfertilization cambisoil modal after conversion to kultizem horticka was further fertilized in version P compost industry (communal) and version H compost humus (agricultural) containing 13,72% of humus and 22,78% of the primary organic matter over a period of 6 years dose 50 t / ha annually. Fertilization with an actual compost H in organically fertilized soil reflected not only by increasing the ion exchange capacity of the soil, but also a significant improvement of water regime of soil, manifested by a quarter greater ability to maintain the water in the soil and 44% lower amount of water, physiologically ineffective.
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Vztah výměnné acidity a iontovýměnné kapacity v kambizemích Jihočeského kraje.NOVÁK, Jiří January 2016 (has links)
Literature search was processed , which were generally described concepts relating to soil complex, but also various soil types, with a focus on cambisol South Bohemia. Additionally the general explained concepts regarding acidification and ion-exchange complex soils. In the practical part of the work was determined by measurement of exchangeable soil acidity. Based on this measurement Soils were evaluated as slightly acidic. It was also calculated the need for healing liming locations. It was also determined the maximum sorption capacity. Soil collected on site has been categorized soils with moderate capacity ion-exchange sorption complex.
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Vliv technologie kompostování biologicky rozložitelných odpadů na kvalitu kompostuDVOŘÁK, Zdeněk January 2018 (has links)
The thesis deals with composting and ways of handling biodegradable waste and biodegradable municipal waste. It explains the terms related to composting and processing of BW and BMW and clarifies the difference between humus and primary organic matter and its composition. Furthermore, the thesis covers qualitative and quantitative features of compost, raw material composition of the dump, and factors influencing the process of decomposition itself. The practical part of the thesis describes the quality of the compost from the municipal composting plant Písek. This part also includes a description of the composting plant and a description of the composting process. The main part and the goal of the thesis is to determine the ion-exchange capacity T according to Sandhoff and to suggest the optimal composting technology in the Municipal composting plant Písek.
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Caractérisation physico-chimique des argiles marocaines : application à l’adsorption de l'arsenic et des colorants cationiques en solution aqueuse / Physico-chemical characterization of Moroccan clays : application for adsorption of arsenic and cationic dyes in aqueous solutionBentahar, Yassine 28 October 2016 (has links)
De nos jours les ressources en eau potable sont fortement réduites suite à une augmentation démographique accompagnée d’une forte industrialisation et d’un développement intensif de l’agriculture. Les rejets de micropolluants d’origine variable (pesticides, colorants, phénols, métaux lourds…) dans l’environnement ne cessent d’augmenter. Ces polluants, toxiques et peu dégradables, sont en général à l’origine de nombreux effets nocifs sur la santé. Ils affectent aussi directement l’équilibre des écosystèmes suite à la dégradation de la qualité des différents milieux de l’environnement (sol, eau, air). D’où le souci de développer des procédés qui œuvrent à la préservation des ressources hydriques contre la pollution par le traitement à la source des eaux polluées. L’application des adsorbants naturels et abondants comme l’argile pour le traitement des eaux est une voie légitime pour préserver le capital hydrique. C’est pourquoi le présent travail de recherche s’est articulé autour de la caractérisation physico-chimique d’une série d’argiles naturelles échantillonnées dans la région Nord du Maroc. Plusieurs techniques ont été sollicitées : La DRX, SFX, FTIR, ATG, la volumétrie d’adsorption d’azote, l’électrophorèse, outre la détermination de quelques propriétés physico-chimiques comme la CEC et le COT. Ceci nous a permis d’établir une série de données avec les différentes propriétés de ces matériaux. Elle peut être ainsi sollicitée pour orienter l’utilisation de ces matériaux selon le besoin. Dans une deuxième étape, nous avons étudié l’adsorption de l’arsenic et des contaminants organiques (le bleu de méthylène et le violet de méthylène) par les argiles / Today drinking water resources are greatly reduced due to population increase accompanied by high industrialization and intensive agricultural development. Releases of varying micropollutants (pesticides, dyes, phenols ...) in the environment are increasing. These pollutants, toxic and poorly degradable, are usually the source of many harmful health effects. They also directly affect the balance of ecosystems following the deterioration of the quality of various environmental medium (soil, water, air). Hence the concern to develop methods that work to preserve water resources against pollution by treating polluted sources. The application of natural and abundant adsorbents like clay in the water treatment is a legitimate way to preserve the water capital. That is why my research is articulated around the physicochemical characterization of a series of natural clays sampled in the northern region of Morocco. Several techniques have been sought: XRD, XRF, FTIR, TGA, The BET-N2 specific surface area, electrophoresis. Furthermore the determination of some physicochemical properties such as CEC and TOC. This allowed us to establish a database with the different properties of these materials. This database may be sought to guide the use of these materials according to their nature. In a second step, we studied the adsorption of arsenic and organic contaminants (methylene blue and methylene violet) by clays. The kinetics of equilibrium adsorbent / adsorbate is an essential step to optimize the conditions for determination of adsorption isotherms
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Blending of Proton Conducting CopolymersWeißbach, Thomas 20 October 2010 (has links) (PDF)
Highly proton conducting polymers for operation in hydrogen/oxygen proton exchange membrane fuel cells (PEMFCs) provide often a poor mechanical strength due to high water contents. To strengthen the conducting polymers, blends with different ratios of partially fluorinated sulfonic acid graft and diblock copolymers with perfluorinated polymers were prepared. To analyze the effect of the different quantities of the compounds, with regard to water sorption and proton conducting properties, membranes were prepared by dissolving the components and drop casting.
Partially sulfonated poly([vinylidene difluoride-co-chlorotrifluoroethylene]-g-styrene) (P(VDF-co-CTFE)-g-SPS) was blended with polyvinylidene difluoride (PVDF), decreasing the ion exchange capacity (IEC). The blended polymers absorbed less water. However, the by AC impedance spectroscopy determined proton conductivity stayed stable or increased slightly. The effective proton mobility remained constant. Partially sulfonated poly([vinylidene difluoride-co-hexafluoropropylene]-b-styrene) (P(VDF-co-HFP)-b-SPS) with two different PS-block lengths were blended with different amounts of poly(vinylidene difluoride-co-hexafluoropropylene) (P(VDF-co-HFP)). In that case, the polymers absorbed less water and the proton conductivity decreased stepwise by adding more than 20 wt% P(VDF-co-HFP). The results indicate that a blending of P(VDF-co-CTFE)-g-SPS with PVDF inhibits swelling without having an effect on the proton conductivity, though water sorption and IEC are reduced.
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