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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Development and Validation of Methods for Characterization of Multi-Component Systems in Preparative LC / Utveckling och Validering av Metoder för Karaktärisering av Flerkomponentsystem vid Preparativ Vätskekromatografi

Arnell, Robert January 2006 (has links)
<p>This thesis concerns the development and validation of methods for characterization of multi-component preparative LC systems. Measurements of competitive adsorption isotherms are performed to gain detailed information about the interactions inside the chromatography column. This information increases our understanding of the separation process and makes it possible to perform computer simulations and numerical optimizations to find optimal operating conditions.</p><p>The methods under focus are called “the tracer-pulse method”, “the inverse method”, and “the inverse method on plateaus”. They are extensions of existing methods, with new experimental and numerical procedures to enable rapid and accurate multi-component adsorption isotherm determination. In the validation it was shown that they can produce results agreeing with traditional methods and that the acquired adsorption isotherm parameters can be used in simulations to accurately predict the outcome of preparative LC separations.</p><p>The methods were used to characterize several complex LC systems and two phenomena were discovered and theoretically treated: 1) The presence of invisible deformed peaks in single-component systems. 2) Peak deformations encountered with modern chiral stationary phases, caused by strongly adsorbed eluent additives. The latter type of deformation was highly tuneable and it was possible to adjust the enantiomer peak shapes so that the peaks tailed in opposite directions with the sharp sides in between, yielding baseline resolution at remarkably high sample loads.</p><p>In a final applied study both the LC-based perturbation peak method and a biosensor method based on surface plasmon resonance (SPR) were used for the first time for detailed characterization of chiral drug-protein interactions. The fundamental properties of the two very different methods were compared and it was found that the LC method is more suitable for multi-component analysis and that the SPR method is more suitable for stronger interactions.</p>
42

Development and Validation of Methods for Characterization of Multi-Component Systems in Preparative LC / Utveckling och Validering av Metoder för Karaktärisering av Flerkomponentsystem vid Preparativ Vätskekromatografi

Arnell, Robert January 2006 (has links)
This thesis concerns the development and validation of methods for characterization of multi-component preparative LC systems. Measurements of competitive adsorption isotherms are performed to gain detailed information about the interactions inside the chromatography column. This information increases our understanding of the separation process and makes it possible to perform computer simulations and numerical optimizations to find optimal operating conditions. The methods under focus are called “the tracer-pulse method”, “the inverse method”, and “the inverse method on plateaus”. They are extensions of existing methods, with new experimental and numerical procedures to enable rapid and accurate multi-component adsorption isotherm determination. In the validation it was shown that they can produce results agreeing with traditional methods and that the acquired adsorption isotherm parameters can be used in simulations to accurately predict the outcome of preparative LC separations. The methods were used to characterize several complex LC systems and two phenomena were discovered and theoretically treated: 1) The presence of invisible deformed peaks in single-component systems. 2) Peak deformations encountered with modern chiral stationary phases, caused by strongly adsorbed eluent additives. The latter type of deformation was highly tuneable and it was possible to adjust the enantiomer peak shapes so that the peaks tailed in opposite directions with the sharp sides in between, yielding baseline resolution at remarkably high sample loads. In a final applied study both the LC-based perturbation peak method and a biosensor method based on surface plasmon resonance (SPR) were used for the first time for detailed characterization of chiral drug-protein interactions. The fundamental properties of the two very different methods were compared and it was found that the LC method is more suitable for multi-component analysis and that the SPR method is more suitable for stronger interactions.
43

A comparison of the reactivity of different synthetic calcium carbonate minerals with arsenic oxyanions

Mandal, Abhishek 14 January 2009
This study was conducted to determine how the structure and surface chemistry of bulk CaCO3 differs from that of nanometer-sized CaCO3 and then to determine rate, extent and mechanisms of As adsorption on various synthetic CaCO3 materials. Additionally, we sought to devise a chemical CaCO3 precipitate that approximates biogenic CaCO3. The bulk CaCO3 precipitation was performed by using a solution that was highly oversaturated so that large CaCO3 precipitates rapidly form. Two different methods were employed for the synthesis of nanometer size CaCO3 i) an in situ deposition technique and ii) an interfacial reaction (water in oil emulsion). Mineral characterization of all CaCO3 precipitates was done with Nitrogen Porosimetry (Brunauer Emmett Teller method), particle size analysis, X-ray diffraction and Fourier Transform Infrared/ Fourier Transform Raman spectroscopy. The principal objective of the research was to assess the overall reactivity of As(III) and As(V) with different synthetic CaCO3 minerals. This was accomplished by i) running adsorption isotherms (varying As concentration), ii) measuring pH envelopes (varying pH at a fixed concentration) and iii) kinetic experiments (varying reaction time). Also, electrophoretic mobility experiments were performed in the presence of As(III) and As(V), and these studies revealed that As(III) forms stronger inner-sphere complexes with CaCO3 than As(V). Also, it was found that nanometer-sized CaCO3 prepared via deposition formed stronger inner-sphere complexes with As oxyanions (q = 5.26 µmol/m2) compared to either nano-sized CaCO3 from interfacial reactions (q = 4.51 µmol/m2) or bulk CaCO3 (q = 4.39 µmol/m2).<p> The PEG-based nano CaCO3 prepared by an in-situ deposition technique presents a novel and readily available synthesis route that can be used as proxy for the biogenic CaCO3 known to be present in many different environmental conditions. The results of this study suggest that CaCO3 can be used as a sorbent for As in groundwater.
44

A comparison of the reactivity of different synthetic calcium carbonate minerals with arsenic oxyanions

Mandal, Abhishek 14 January 2009 (has links)
This study was conducted to determine how the structure and surface chemistry of bulk CaCO3 differs from that of nanometer-sized CaCO3 and then to determine rate, extent and mechanisms of As adsorption on various synthetic CaCO3 materials. Additionally, we sought to devise a chemical CaCO3 precipitate that approximates biogenic CaCO3. The bulk CaCO3 precipitation was performed by using a solution that was highly oversaturated so that large CaCO3 precipitates rapidly form. Two different methods were employed for the synthesis of nanometer size CaCO3 i) an in situ deposition technique and ii) an interfacial reaction (water in oil emulsion). Mineral characterization of all CaCO3 precipitates was done with Nitrogen Porosimetry (Brunauer Emmett Teller method), particle size analysis, X-ray diffraction and Fourier Transform Infrared/ Fourier Transform Raman spectroscopy. The principal objective of the research was to assess the overall reactivity of As(III) and As(V) with different synthetic CaCO3 minerals. This was accomplished by i) running adsorption isotherms (varying As concentration), ii) measuring pH envelopes (varying pH at a fixed concentration) and iii) kinetic experiments (varying reaction time). Also, electrophoretic mobility experiments were performed in the presence of As(III) and As(V), and these studies revealed that As(III) forms stronger inner-sphere complexes with CaCO3 than As(V). Also, it was found that nanometer-sized CaCO3 prepared via deposition formed stronger inner-sphere complexes with As oxyanions (q = 5.26 µmol/m2) compared to either nano-sized CaCO3 from interfacial reactions (q = 4.51 µmol/m2) or bulk CaCO3 (q = 4.39 µmol/m2).<p> The PEG-based nano CaCO3 prepared by an in-situ deposition technique presents a novel and readily available synthesis route that can be used as proxy for the biogenic CaCO3 known to be present in many different environmental conditions. The results of this study suggest that CaCO3 can be used as a sorbent for As in groundwater.
45

Dessulfurização de butano líquido por adsorção mediante utilização de peneira molecular 13X. / Desulfurization of liqui-phase butane by adsorption using molecular sieves 13X.

Alyne Freitas da Silva Bordalo Rodrigues 11 October 2016 (has links)
Atualmente, o tipo de propelente para produtos em aerossol mais usado no mundo é uma mistura de hidrocarbonetos leves (butano e propano - sendo o primeiro em maior proporção). Parte de seu processo de produção é a dessulfurização do butano líquido, através de adsorção em leito fixo usando peneiras moleculares 13X. A literatura científica não apresenta muitas publicações sobre o tema e considerando que a técnica de adsorção é fortemente dependente de dados experimentais para seu maior entendimento, é objetivo deste trabalho estudar este processo através do equilíbrio de adsorção, das curvas de ruptura e do desenvolvimento de um modelo matemático que represente o funcionamento de uma coluna de adsorção de leito fixo a temperatura constante. Obtiveram-se dados sobre o equilíbrio de adsorção por meio de ensaios em banho finito comparando-se a interação de diferentes compostos de enxofre com a peneira molecular 13X e o efeito da temperatura. Utilizou-se a técnica de cromatografia gasosa como método analítico para obtenção dos teores de compostos sulfurados e de hidrocarbonetos. O modelo de Langmuir apresentou bom ajuste aos dados experimentais. Avaliando-se a interação dos componentes sulfurados com a zeólita 13X, identificou-se diferenças significativas, sendo a maior em ordem decrescente: etil-mercaptana, n-propil-mercaptana e terc-butil-mercaptana, respectivamente. A dinâmica do processo de adsorção foi estudada através da obtenção das curvas de ruptura em leitos em escala laboratorial e piloto. Avaliaram-se as influências da variação da concentração de entrada da n-propil-mercaptana e da velocidade do fluido em leito fixo recheado com zeólitas 13X, mantendo os demais parâmetros constantes. Conforme esperado o aumento da concentração inicial reduz o tempo de ruptura, aumenta a quantidade total adsorvida pelo leito e não altera o comportamento da zona de transferência de massa (ZTM). Analisando-se a elevação da velocidade, nota-se também uma diminuição no tempo de ruptura e um aumento da ZTM. O modelo matemático apresentado considera os balanços de massa microscópicos aplicados ao leito, os fenômenos de transporte de massa com modelo de dispersão axial e transporte por convecção da fase líquida para a superfície da partícula e as isotermas de adsorção. As equações diferenciais parciais resultantes foram adimensionalizadas e resolvidas empregando-se o método de diferenças finitas, implementado por código Matlab®. A partir da simulação matemática das condições experimentais obtiveram-se os parâmetros de dispersão axial e de transferência de massa que possibilitaram uma boa reprodução do tempo de ruptura quanto do perfil da zona de transferência de massa para os experimentos em escala laboratorial e piloto. / Currently, the kind of propellant for aerosol products most widely used in the world is a blend of light hydrocarbons (butane and propane - the first in greater proportion). Part of the production of propellant is the desulfurization of liquid-phase butane by molecular sieves 13X in a fixed bed. The scientific literature concerning the adsorption of the mercaptans using zeolite are scarce and considering that the adsorption technique is strongly dependent on experimental data for its better knowlegde, the aim of this work was to study this process by adsorption equilibrium, the breakthrough curves and the development of a mathematic model, simulation and comparison with the operation of a fixed-bed pilot and laboratory-scale column. Adsorption equilibrium parameters were obtained using finite bath experiment and comparing the interaction of different sulfur compounds with molecular sieve 13X and the temperature effect. It was used the gas chromatography as an analytical method in order to obtain the levels of hydrocarbons and sulfur compounds. The Langmuir model well fit the experimental data. Significant differences were identified in the interaction of the sulfur components with zeolite 13X. The major interactions of the sulfur components are in decreasing order: ethyl-mercaptan, n-propyl-mercaptan and terc-butyl-mercaptan. The dynamic of the adsorption process was studied by obtaining the breakthrough curves in laboratory and pilot scale. It was investigated the influence of the initial concentration of n-propyl mercaptan and the fluid velocity in a fixed bed packed with zeolite 13X keeping the other parameters constant. As it was expected, as the inlet sulfur concentration increases the break point time decrease, and enhances the total amount adsorbed by the bed. Analyzing the increase in velocity on the breakthroug profile, it was noted that also decreases the break point time and causes a greater decline of the curve resulting in greater ZTM and anticipating the bed saturation time. The model equations account the mass balance applied in the flowing liquid phase in the column, transport phenomena as the effect of axial dispersion and convection from liquid phase to the adsorbent surface and adsorption isotherm. Finite difference method was used to solve the dimensionless general partial differential equations and it was implemented by Matlab® software. From mathematical simulation of experimental conditions it were obtained the axial dispersion parameters and mass transfer coefficient which allowed a fair agreement in predicting break point time and the mass transfer zone profile.
46

LIGNOCELLULOSIC ACTIVATED WASTE USE ADSORBENTS IN TOXIC METALS IONS REMOVAL: BATCH AND COLUMN STUDIES USING DESING EXPERIMENTAL / Uso de ResÃduos LignocelulÃsicos Ativados como Adsorventes na RemoÃÃo de Ãons MetÃlicos TÃxicos: Estudos de Batelada e Coluna Utilizando Planejamento Experimental.

Diego de Quadros Melo 27 November 2015 (has links)
FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / The tururi and buriti fibers, and the castor bean stalks are extremely efficient to sorption of metal ions from aqueous solutions. In this study, the adsorbents were activated with different concentrations of alkali solutions (5, 7, 10 and 15% w/v). The materials were characterized by analytical techniques as infrared, X-ray Diffraction (XRD) and Thermogravimetry analysis. The infrared spectra revealed that associated groups to macromolecules of hemicellulose and lignin after alkaline activation have less intensity compared to the initial samples. The XRD revealed, that after castor bean stalks alkaline activation, the presence of the cellulose type II peaks, which did not occur with tururi and buriti fibers. The fluorescence X-ray data showed that the cations present in the initial adsorbents, K+ and Ca2 + are exchanged by Cu (II), Ni (II), Cd (II) and Pb (II) in the sorption process. Studies of the influences of variables: mass of adsorbent; agitation rate; the initial pH and concentration using a fractional factorial design 24-1 demonstrated that all variables affect the response (adsorption capacity mg g-1). As a result for a larger value of qtotal, conditions were observed while maintaining the pH at 5.5; mass of the adsorbent 50 mg; agitation at 200 rpm and the initial concentration: 500 mg L-1. The adsorption kinetics revealed fast adsorption process, about 30 minutes, and good fitting to pseudo-second-order theoretical model to all adsorption process studied. Intraparticle diffusion models as Weber-Morris and Boyd were testes in order to study the limiting steps of the process.The results showed that for tururi and buriti fibers (with the exception of nickel ions) the rate-limiting step is not the intraparticle diffusion, while for the castor bean stalks, it was found that the rate-limiting step of the process is the intraparticle diffusion. The study of monoelement and multielement systems were performed at pH 5.5, initial concentrations from 20-500 mg L-1, which the experimental data were fitted to the Langmuir, Freundlich and Sips theoretical models. The tururi fibers adsorption capacities (mg g-1) in monoelementar and multielement system follows the order Pb (188.79)> Cd (92.20)> Cu (32.82)> Ni (22.23) and Cd (77.53)> Pb (43.93)> Cu (24.99)> Ni (19.51), respectively. Buriti fibers adsorption capacities (g-1 mg) in monoelementar and multielement systems follows the order of Cu (143.1)> Pb (112.1)> Ni (103.7)> Cd (86.33) and Pb (69.12)> Cu (49.28)> Ni (45.10)> Cd (24.95), respectively. Castor bean stalks adsorption capacities (g-1 mg) in in monoelementar and multielement systems follows the order of Pb (175.1)> Cd (124.8)> Ni (111.1)> Cu (89.23) and Cu (56.78)> Pb (55.82)> Cd (44.72)> Ni (43.48), respectively. The results showed a better fit for the Sips model, relating to a heterogeneous adsorption. Fixed bed studies using castor bean stalks checking the influence of variables adsorbent flow (1, 2 and 3 mL min-1), the height of the column (5, 7 and 10 cm) and initial concentration (100 , 200, 300 mg L-1) by the Box-Behnken planning revealed that there were no influence between the variables in the studied. The breakthrough curves were well fitted to the Thomas model. The study in real effluent with Cu (II) (galvanoplastic sector) was carried out using the optimized condition: flow (1 ml min-1); bed height (10 cm) initial concentration: (245.5 mg L-1) and it was found adsorption capacity of 32.42 mg g-1. The mamoneira stalks adsorbent was used for five cycles to verify their potential reuse, and it was found no significant efficiency losses. / As fibras tururi, buriti e talos da mamoneira sÃo resÃduos lignocelulÃsicos extremamente eficientes na sorÃÃo de metais de soluÃÃes aquosas. Neste trabalho, eles foram ativados com diferentes concentraÃÃes de soluÃÃes alcalinas (5, 7, 10 e 15% m/v). Os materiais foram caracterizados pelas tÃcnicas analÃticas de Infravermelho, DifraÃÃo de Raios-X (DRX) e Termogravimetria. Os espectros de infravermelho revelaram que os grupos associados Ãs macromolÃculas de hemicelulose e lignina diminuem em intensidade ou desaparecem apÃs a ativaÃÃo alcalina. Os DRX revelaram que apÃs a ativaÃÃo alcalina, os talos da mamoneira apresentaram picos de celulose tipo II, o que nÃo ocorreu com as fibras de tururi e buriti. O dados de FluorescÃncia de Raios-X revelaram que os cÃtions presentes nos adsorventes como Na(I) e Ca(II) sÃo trocados pelos Ãons Cu(II), Ni(II), Cd(II) e Pb(II) no processo de sorÃÃo. Os estudos das influÃncias das variÃveis: massa do adsorvente; taxa de agitaÃÃo; pH e concentraÃÃo inicial utilizando planejamento experimental fracionÃrio 24-1 demostrou que todas as variÃveis afetaram a resposta (capacidade de adsorÃÃo mg g-1). Como resultado para um maior valor de qtotal, as condiÃÃes observadas foram mantendo o pH em 5,5; massa do adsorvente em 50 mg; taxa de agitaÃÃo em 200 rpm e concentraÃÃo inicial 500 mg L-1. A cinÃtica de adsorÃÃo revelou rÃpida adsorÃÃo, cerca de 30 minutos em geral, seguindo o modelo de pseudo-segunda ordem em todos os processos adsortivos. Modelos de difusÃo intrapartÃcula como de Webber-Morris e Boyd foram estudados a fim de determinar as etapas limitantes do processo. Os dados evidenciaram que para as fibras de tururi e buriti (com exceÃÃo dos Ãons nÃquel) a etapa limitante da velocidade nÃo à a difusÃo intraporo, enquanto para os talos de mamoneira foi verificado que a etapa limitante do processo à a difusÃo intrapartÃcula. O estudo com sistema monoelementar e multielementar foi realizado em pH 5,5, concentraÃÃes variando de 20-500 mg L-1, nos quais os dados foram aplicados aos modelos de Langmuir, Freundlich e Sips. As capacidades de adsorÃÃo (mg g-1) em sistema monoelementar e multielementar das fibras de tururi segue a ordem Pb(188,79)> Cd(92,20)> Cu(32,82)> Ni(22,23) e Cd(77,53)> Pb(43,93)> Cu(24,99)> Ni(19,51), respectivamente. As capacidades de adsorÃÃo (mg g-1) das fibras de buriti em sistema monoelementar e multielementar segue a ordem Cu(143,1)> Pb(112,1)> Ni(103,7) > Cd(86,33) e Pb(69,12)> Cu(49,28)> Ni(45,10)> Cd(24,95), respectivamente. As capacidades de adsorÃÃo (mg g-1) dos talos de mamoneira em sistema monoelementar e multielementar segue a ordem Pb(175,1)> Cd(124,8)> Ni(111,1)> Cu(89,23) e Cu(56,78)> Pb(55,82)> Cd(44,72)> Ni(43,48), respectivamente. Em geral, os resultados evidenciaram melhor aplicabilidade ao modelo de Sips, o qual prediz que os sÃtios disponÃveis para adsorÃÃo sÃo heterogÃneos. Em relaÃÃo ao estudo de adsorÃÃo em leito fixo utilizando talos de mamoneira, a verificaÃÃo da influÃncia das variÃveis: fluxo do adsorvente (1, 2 e 3mL min-1), altura da coluna (5, 7 e 10 cm) e concentraÃÃo inicial (100, 200, 300 mg L-1) pelo planejamento de Box-Behnken, revelou que nÃo hà influencia mutua entre as variÃveis no intervalo estudado. As curvas de ruptura experimentais foram bem aplicadas ao modelo teÃrico de Thomas. O estudo com efluente real de Ãons Cu (II) (setor galvanoplÃstico) utilizando a condiÃÃo otimizada: fluxo (1mL min-1); altura de leito (10 cm) e concentraÃÃo inicial: (245,5 mg L-1) obteve 32,42 mg g-1 de capacidade de adsorÃÃo O adsorvente talos de mamoneira foi utilizado por cinco ciclos para verificar seu potencial de uso, nÃo havendo perdas significativas de eficiÃncia.
47

Fluoration pour la synthèse de matériaux à base de carbone pour le stockage de l'énergie / Fluorination for the synthesis of carbon-based materials for energy storage

Batisse, Nicolas 06 December 2011 (has links)
Des carbones dérivés de carbures à porosité monodisperse et nanocentrée autour de 0,6 nm ont été préparés par fluoration de carbures via l’arrachement sélectif de l’élément métallique et le maintien de l’empreinte carbonée initiale. Les carbures précurseurs ont été choisis parmi deux des classes de carbures à savoir interstitiels pour le carbure de titane et de niobium et covalents pour le carbure de silicium. La fluoration directe procédant sous flux d’une atmosphère de fluor pur apparait comme étant la seule méthode de fluoration apte à déstabiliser les poudres cristallisées. Appliquée au carbure de titane, des matériaux à teneur variable en carbone et en trifluorure de titane ont été obtenus et caractérisés structuralement par Diffraction des Rayons X quantitative, spectroscopies IR et Raman et leur texture sondée par Microscopie Electronique à Balayage et à Transmission et isothermes d’adsorption à l’azote à 77K. Ils ont aussi été évalués comme matériau d’électrode de supercondensateurs. La fluoration du carbure de silicium pour la stabilisation d’une phase carbonée est plus difficile et seule l’abaissement de la cristallinité du carbure par l’utilisation d’une mise en forme de type couche mince combinée à une méthode de fluoration alternative par décomposition de l’agent fluorant XeF2 ont permis d’obtenir une couche mince de carbone nanostructurée valorisable comme lubrifiant solide et aux propriétés de mouillabilité modulables. / Carbide-derived Carbons (CDC) with monodisperse ultramicroporosity have been prepared by carbide fluorination thanks to selective etching of metallic element. The chosen carbides precursors were titanium and niobium carbides, and silicon carbides from interstitial and covalent carbide family, respectively. Direct fluorination proceeding by a pure flow of 1 atm. of molecular fluorine is the only fluorination way which leads to the transformation of the powdered and highly crystallized carbide into some carbons. Materials with different ratio of carbon and solid titanium trifluoride were successfully obtained by direct fluorination of titanium carbide, characterized by quantitative XRD, IR and Raman spectroscopies and Scanning and Transmission Electronic Microscopies and used in supercapacitors. The direct fluorination of silicon carbide in order to form carbon is more difficult because of the competition between carbon formation and its degradation into gaseous carbon fluorides. To success in our goal, thin film morphology was used as precursor. However, an accurate fluorination way is needed and decomposition of XeF2 fluorinating agent was chosen. Thin films with variable thickness of nanostructured carbon at the surface were obtained and used as solid lubricant with tunable wettability properties.
48

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 solution

Bentahar, 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
49

Konjugované porézní polymery odvozené od diethynylarenů řetězovou polymerizací a polycyklotrimerizací / Conjugated porous polymers derived from diethynylarenes by chain-growth polymerization and polycyclotrimerization

Slováková, Eva January 2015 (has links)
4 ABSTRACT The synthesis has been described yielding a new type of rigid conjugated polymer networks which possess a high content of permanent micropores and macropores and exhibit high surface areas up to 1469 m2/g. The networks have been prepared via chain-growth coordination polymerization catalysed with insertion catalysts based on Rh complexes. This polymerization has been newly applied to bifunctional acetylenic monomers of diethynylarene type (1,4-diethynylbenzene, 1,3-diethynylbenzene and 4,4'-diethynylbiphenyl). The covalent structure of the networks consists of the polyacetylene main chains densely connected by arylene struts. The W and Mo metathesis catalysts have been revealed as inefficient for the synthesis of these networks. The increase in the polymerization temperature and time has been shown to affect positively the content and the diameter (up to 22 nm) of the mesopores in the networks. A mechanism has been proposed that explains the mesopores formation as a result of mutual knitting of small particles of the microporous polymer. The application of emulsion polymerization technique allowed to prepare texturally hierarchical polyacetylene networks possessing interconnected open macropores (diameter up to 4,8 μm) the walls of which exhibited micro/mesoporous texture. It was demonstrated...

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