Dissertations / Theses: 'Isotherm model'

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Ho, Loi. "Determination of Ibuprofen Isotherm Using Supercritical Fluid Chromatography." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4075.

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Chromatography is widely used to determine physiochemical properties data including adsorption isotherm. In the separation of enantiomers through sorptive processes, supercritical fluids allow efficient and green alternatives to liquid solvent based systems. The isotherm information is vital in the development of operating policies and design of preparative chromatographic or moving bed separation schemes. Determination of sorption isotherms from experimental chromatographic elution data is automated and compared with different chromatogram model. Procedures were developed and validated for separation of R- and S- ibuprofen with supercritical 〖CO〗_2 and ethanol mixture as the mobile phase over a chiral stationary phase. The isotherms for the Langmuir, Freundlich, and Toth gave the similar results with a small residual for S-Ibuprofen at 150 bars and 40℃. Relative small amount of sample can be use from experiments to determine isotherms data that later be use for scale-up of the sorptive processes in industry to reduce time and cost.

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Yu, Lin. "Modeling the Longevity of Infiltration System for Phosphorus Removal." Thesis, KTH, Miljögeokemi och ekoteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96097.

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A new modeling method for estimation of the longevity of infiltration system was suggested in this study. The model was one-dimensional, based on results from long-term infiltration sites in Sweden, taking some physical and chemical parameters as controlling factors. It defines the longevity of infiltration systems as the time during which the P solution in effulent is under national criteria (1 mg/L in this study), and it aims at providing the longevity for any given point of the infiltration system. The soil in the model was assumed to be totally homogenous and isotropic and water flow was assumed to be unsaturated flow and constant continuous inflow. The flow rate was calculated from the Swedish criteria for infiltration systems. The dominant process in the model would be the solute transport process; however, retardation controlled by sorption would play a more important role than advection and dispersion in determining the longevity in the model. By using the definition of longevity in this study, the longevity of the three soil columns at 1 m depth (Knivingaryd, Ringamåla and Luvehult) were 1703 days, 1674 days and 2575 days. The exhaustion time of the three soil columns under inflow of 5 mg/L were 2531 days, 2709 days and 3673 days. The calculated sorbed phosphorus quantity for soil from sites Kn, Lu and Ri when they reach estimated longevity were 0.177, 0.288 and 0.168 mg/g, while the maximum sorption of Kn, Lu and Ri were 0.182, 0.293 and 0.176 mg/g separately. From the result of sensitivity study of the model, the sorption capacity and flow velocity were most important to the longevity of the infiltration system. Lower flow velocity and higher P sorption capacity extend the longevity of an infiltration bed. Due to the sorption isotherm selected in this study and the assumption of instant equilibrium, the sorption rate of the soil column was quite linear, although the estimated longevity was much shorter than the real exhaustion time of the soil column. In fact the soil has almost reached its sorption maximum when the system reaches its longevity.

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Sbizzaro, Mariana. "Adsorção de atrazina em biocarvões obtidos a partir de colmo de bambu." Universidade Estadual do Oeste do Parana, 2016. http://tede.unioeste.br:8080/tede/handle/tede/272.

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The agricultural sector has great influence in Brazilian economy. Furthermore, agricultural yield has been associated with pesticides application during crop cycle, which atrazine is applied for example, since it can cause environmental contamination when it does not reach its target. Thus, there are some essential and imperative options that can minimize contamination and negative impacts during agricultural practices. So, present study aimed at evaluating the ability of three biochars in atrazine adsorption. Therefore, three biochars produced from bamboo culm were used, whose species is Phyllostachys aurea, and temperature ranged at 350 ºC, 450 ºC and 550 ºC. The three studied biochars were named as BE350, BE450 and BE550. They were characterized based on their physical and chemical properties by elemental analysis, characterization of functional groups (Infrared Spectroscopy Fourier Transform - FTIR), surfaces morphology evaluation (Scanning Electron Microscopy - SEM) as well as specific surface area (ASEBET) and porosity. A kinetic study was carried out to determine the equilibrium period of adsorption process and the kinetic mechanism that controls such process. Langmuir and Freundlich isotherms were also modeled during this trial. Atrazine determination, after the adsorption test, was carried out by High Performance Liquid Chromatography (HPLC). The obtained analyses showed that the adsorption capacity of biochars decreased in the following order: BE 450> BE 350 > BE 550, and such capacity has been associated with the physical and chemical characteristics of biochars. The three studied biochars are well represented by the kinetic model of pseudo-second order. At last, all biochars have shown high affinity to adsorb atrazine; however, the biochar that was produced at 450 ºC has shown the highest adsorption capacity.
O setor agrícola possui grande destaque na economia brasileira, a produção agrícola está associada ao uso de pesticidas durante o ciclo das culturas, como é o caso da atrazina, que pode causar a contaminação do ambiente, quando não atinge seu alvo. Sendo assim, alternativas que minimizem as contaminações e impactos negativos da prática agrícola são essenciais e urgentes. Desta forma, o presente estudo teve por objetivo avaliar a capacidade de três biocarvões, em adsorver o herbicida atrazina. Para tanto, foram utilizados três biocarvões, produzidos a partir do colmo de bambu, da espécie Phyllostachys aurea à 350ºC, 450ºC e 550ºC, nomeados BE350, BE450 e BE550. Os biocarvões foram caracterizados quanto as propriedades físicas e químicas, por meio de análise elementar, caracterização de grupos funcionais (Espectroscopia de Infravermelho com Transformada de Fourier - FTIR), avaliação da morfologia das superfícies (Microscopia Eletrônica de Varredura - MEV), bem como, área superficial específica (ASEBET) e porosidade. Estudo cinético foi realizado, visando determinar o tempo de equilíbrio do processo de adsorção, bem como, o mecanismo cinético que controla o processo. Também foram modeladas isotermas de Langmuir e Freundlich. A determinação da atrazina, após os ensaios de adsorção, foi realizada por Cromatografia Líquida de Alta Performance (CLAE). As análises realizadas apontaram que a capacidade de adsorção dos biocarvões diminuiu na ordem de BE 450 > BE 350 > BE 550, e tal capacidade está associada às características físicas e químicas dos biocarvões. Os três biocarvões são bem representados pelo modelo cinético de pseudo-segunda ordem. Todos biocarvões exibiram elevada afinidade para a adsorção do herbicida atrazina, contudo, o biocarvão produzido à 450 ºC demonstra maior capacidade de adsorção

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Liu, Jia. "Development of a Design-Based Computational Model of Bioretention Systems." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/52703.

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Multiple problems caused by urban runoff have emerged as a consequence to the continuing development of urban areas in recent decades. The increase of impervious land areas can significantly alter watershed hydrology and water quality. Typical impacts to downstream hydrologic regimes include higher peak flows and runoff volumes, shorter concentration times, and reduced infiltration. Urban runoff increases the transport of pollutants and nutrients and thus degrades water bodies adjacent to urban areas. One of the most frequently used practices to restore the hydrology and water quality of urban watersheds is bioretention (also known as a rain garden). Despite its wide applicability, an understanding of its multiple physiochemical and biological treatment processes remains an active research area. To provide a wide ability to evaluate the hydrologic input to bioretention systems, spatial and temporal distribution of storm events in Virginia were studied. Results generated from long-term frequency analysis of 60-year precipitation data demonstrate that the 90 percentile, or 10-year return period rainfall depth and dry duration in Virginia are between 22.9 – 35.6 mm and 15.3 – 25.8 days, respectively. Monte-Carlo simulations demonstrated that sampling programs applied in different regions would likely encounter more than 30% of precipitation events less than 2.54 mm, and 10% over 25.4 mm. Further experimental research was conducted to evaluate bioretention recipes for retaining stormwater nitrogen (N) and phosphorus (P). A mesocosm experiment was performed to simulate bioretention facilities with 3 different bioretention blends as media layers with underdrain pipes for leachate collection. A control group with 3 duplicates for each media was compared with a replicated vegetated group. Field measurement of dissolved oxygen (DO), oxidation-reduction potential (ORP), pH, and total dissolved solids (TDS) was combined with laboratory analyses of total suspended solids (TSS), nitrate (NO3), ammonium (NH4), phosphate (PO4), total Kjeldahl nitrogen (TKN) and total phosphorus (TP) to evaluate the nutrient removal efficacies of these blends. Physicochemical measurements for property parameters were performed to determine characteristics of blends. Isotherm experiments to examine P adsorption were also conducted to provide supplementary data for evaluation of bioretention media blends. The results show that the blend with water treatment residuals (WTR) removed >90% P from influent, and its effluent had the least TDS / TSS. Another blend with mulch-free compost retained the most (50 – 75%) total nitrogen (TN), and had the smallest DO / ORP values, which appears to promote denitrification under anaerobic conditions. Increase of hydraulic retention time (HRT) to 6 h could influence DO, ORP, TKN, and TN positively. Plant health should also be considered as part of a compromise mix that sustains vegetation. Two-way analysis of variance (ANOVA) found that single and interaction effects of HRT and plants existed, and could affect water quality parameters of mesocosm leachate. Based upon the understanding of the physiochemical and hydrologic conditions mentioned previously, a design model of a bioretention system became the next logical step. The computational model was developed within the Matlab® programming environment to describe the hydraulic performance and nutrient removal of a bioretention system. The model comprises a main function and multiple subroutines for hydraulics and treatment computations. Evapotranspiration (ET), inflow, infiltration, and outflow were calculated for hydrologic quantitation. Biomass accumulation, nitrogen cycle and phosphorus fate within bioretention systems were also computed on basis of the hydrologic outputs. The model was calibrated with the observed flow and water quality data from a field-scale bioretention in Blacksburg, VA. The calibrated model is capable of providing quantitative estimates on flow pattern and nutrient removal that agree with the observed data. Sensitivity analyses determined the major factors affecting discharge were: watershed width and roughness for inflow; pipe head and diameter for outflow. Nutrient concentrations in inflow are very influential to outflow quality. A long-term simulation demonstrates that the model can be used to estimate bioretention performance and evaluate its impact on the surrounding environment. This research advances the current understanding of bioretention systems in a systematic way, from hydrologic behavior, monitoring, design criteria, physiochemical performance, and computational modeling. The computational model, combined with the results from precipitation frequency analysis and evaluation of bioretention blends, can be used to improve the operation, maintenance, and design of bioretention facilities in practical applications.
Ph. D.

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Telesford, Dana-Marie Leslie-Ann. "Langmuir Trough and Brewster Angle Microscopy Study of Model Lung Surfactant Monolayers at the Air/Aqueous Interface." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1353516892.

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Delgado, Cano Beatriz. "Caractérisation des matériaux commerciaux et synthétisés destinés à adsorber le méthane et l’oxyde nitreux présents dans des émissions gazeuses et modélisation de l’adsorption." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1073.

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Les activités humaines ont généré une augmentation importante de la concentration de gaz à effet de serre (GES) au cours des 150 dernières années, ce qui est relié à plusieurs problèmes environnementaux, tels que le réchauffement planétaire et les changements climatiques. Le secteur agricole contribue de 8 à 10% aux émissions totales de GES dans l'atmosphère, et les principaux GES émis sont le dioxyde de carbone (CO2), le méthane (CH4) et l'oxyde nitreux (N2O). Le contrôle et la quantification de ces émissions requièrent des technologies qui permettent de les capturer et ou les dégrader, par exemple par adsorption. L'objectif du présent projet est de caractériser des matériaux qui puissent Ãªtre utilisés comme adsorbants des GES et de décrire leurs cinétiques d'adsorption afin d'avoir l'information qui permet de sélectionner des adsorbants pour capturer le CH4 et le N2O à des basses concentrations et à température et pression ambiantes. Pour adsorber le CH4, des adsorbants commerciaux et synthétiques ont été utilisés. Les adsorbants choisis ont été des zéolithes, un biocharbon conditionné au laboratoire et un ZIF (« Zeolitic imidazolate framework », ZIF-8) synthétisé au laboratoire. Ce dernier a été employé aussi pour adsorber du N2O. La capacité d'adsorption de CH4 et de N2O a été évaluée pour chaque adsorbant par de tests dynamiques d'adsorption du gaz sous conditions ambiantes. Ces matériaux ont été caractérisés physiquement et chimiquement afin de corréler leurs propriétés avec la capacité d'adsorption de CH4 et/ou de N2O. Des isothermes d'équilibre ont été utilises pour modéliser les donnés expérimentales. Parmi les différents matériaux utilisés lors de l'adsorption du CH4 à 30 ÂºC et à pressions partielles de CH4 inférieures à 0,40 kPa, les biocharbons présentent la capacité d'adsorption la plus élevée, suivis par le ZIF-8 et les zéolithes commerciales
Human activities contributed with a significant increase in GHG concentrations over the past 150 years and they are related to environmental issues, such as global warming and climate change. The agricultural sector contributes 8 to 10% of total GHG emissions to the atmosphere, being carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) the main GHGs emitted. The control and quantification of these emissions requires technologies which can capture and or degrade these GHG, for example by adsorption. The objective of this project is to characterize adsorbents and to describe their adsorption kinetics in order to select the most suitable for the adsorption of CH4 and N2O at low concentration and at ambient temperature. For CH4 adsorption, commercial and synthesized adsorbents were tested. The selected adsorbents were commercial zeolites, laboratory conditioned biochar and synthesized ZIF ("Zeolitic imidazolate framework"). ZIF was also used for N2O adsorption. The adsorption capacity of CH4 and N2O for each adsorbent was evaluated by dynamic adsorption tests of the gas under atmospheric conditions. These materials were physically and chemically characterized in order to correlate its properties with its CH4 and/or N2O adsorption capacity. The experimental data of gas adsorption were fitted by equilibrium isotherms. Among the different materials used for CH4 adsorption at 30 ÂºC and partial pressures lower than 0.40 kPa, biocharbons presented the highest adsorption capacity, followed by ZIF- 8 and commercial zeolites

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Castada, Hardy Zingalaoa. "Brewster Angle Microscopy Study of Model Lung Surfactant Systems at the Air-Water and Air-Physiological Buffer Interfaces." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1281642097.

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Ferreira, Mário Nogueira. "Estudo da secagem de jabuticaba (polpa e casca) pelo método de camada de espuma." Universidade Federal de Goiás, 2017. http://repositorio.bc.ufg.br/tede/handle/tede/7962.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The objective of this work was to characterize the pulp + jabuticaba shell, the foams of the formulations (F1, F2, F3, F4) and the pulp + jabuticaba shell powder by the foam layer method. It was used jabuticaba of the variety M. cauliflora sp (jabuticaba sabará), harvest 2016. The pulp + jabuticaba bark were characterized as centesimal composition, hydrogenation potential, total titratable acidity, total soluble solids, energy value, water activity and color (a*, b *, L *, h * and C *). The foam was characterized regarding density, the percentage of expansion, stability, and fraction of drained volume, drying curves and mathematical modeling. The pulp + bark of jabuticaba powder was also characterized for the adsorption isotherm, scanning electron microscopy (SEM), antioxidant potential by the DPPH method, ABTS and FRAP, total phenolics, condensed and hydrolyzed tannins, absorption indexes and solubility in water (AI/SW) and milk (IAL / ISL) and oil absorption index (OAI). It was observed that the moisture content, SST, pH, acidity, water activity and color did not change, while all other analyzes were influenced. Formulation F3 was the one that best fit the foam evaluation criteria. The model of Wang and Singh presented the lowest reduced chi-square (χ²) and the highest coefficients of determination (R²), whereas the Page model obtained higher values for the drying rate and lower values for the internal resistance to the formulation F3. It was verified that the formulation F3 presented greater reduction of the moisture ratio as a function of time compared to the other formulations during processing. Therefore, a model can be adjusted in certain bands and not in others, which limits the application of empirical models. The results obtained in this study demonstrate that the pulp foam drying + jabuticaba bark can make a promising alternative in the post harvest of this important fruit since it allows the retention of nutritional components of interest in this product and thus increases the consumption Of this product in powder form.
Objetivou-se com este trabalho caracterizar a polpa+casca de jabuticaba, as espumas das formulações (F1, F2, F3, F4) e da polpa+casca de jabuticaba em pó pelo método de camada em espuma. Utilizou-se jabuticaba da variedade M. cauliflora sp (jabuticaba sabará), safra 2016. A polpa+casca de jabuticaba foram caracterizadas quanto à composição centesimal, pH, acidez total titulável, sólidos solúveis totais, valor energético, atividade de água e cor (a*, b*, L*, h* e C*). A espuma foi caracterizada quanto à densidade, percentual de expansão, estabilidade e fração do volume drenado, curvas de secagem e modelagem matemática. A polpa+casca de jabuticaba em pó foi caracterizada também quanto à isoterma de adsorção, microscopia eletrônica de varredura (MEV), capacidade antioxidante pelo método de DPPH, ABTS e FRAP, fenólicos totais, taninos condensados e hidrolisáveis, índices de absorção e solubilidade em água (IAA/ISA) e em leite (IAL/ISL) e índice de absorção em óleo (IAO). Observou-se que os teores de umidade, SST, pH, acidez, atividade de água e cor não sofreram alterações, enquanto que todas as demais análises foram influenciadas. A formulação F3 foi a que se enquadrou melhor nos critérios de avaliação das espumas. O Wang e Singh foi o que apresentou os menores qui-quadrado reduzido (χ²) e os maiores coeficientes de determinação (R²), já o modelo de Page obteve maiores valores para a taxa de secagem e menores valores para a resistência interna para a formulação F3. Verificou-se que a formulação F3 apresentou maior redução da razão de umidade em função do tempo comparado com as demais formulações durante o processamento. Portanto, um modelo pode-se ajustar em determinadas faixas e não em outras, o que limita a aplicação de modelos empíricos. Os resultados obtidos neste estudo demonstram que a secagem em camada de espuma de polpa+casca de jabuticaba pode tornar uma alternativa promissora na pós-colheita dessa importante fruta, uma vez que, possibilita a retenção de componentes nutricionais de interesse neste produto e assim aumenta o consumo deste produto na forma de pó.

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Gabos, Mariana Bassetto. "Background concentrations and adsorption of selenium in tropical soils." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/11/11140/tde-20092012-164703/.

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Selenium (Se) is a trace element essential to the nutrition of animals. On the other hand, in a narrow concentration range, Se can cause toxicity. The presence of Se in food is related to the concentration of the element in soil. Thus, the knowledge of the Se amount and its behavior in soil are very important to the better manage the environment and to prevent toxicological problems and human deficiency. The objectives of this study were: (i) to quantify the natural content of Se in some Brazilian soils and correlates them with soil attributes; (ii) to evaluate the adsorption of selenite and selenate as a function of pH and Se concentration in tropical soils; (iii) to adjust the constant capacitance model to describe the Se adsorption in tropical soil as compared to empiric models. Se concentrations ranged from <0.08 to 1.61 mg kg-1, with a mean of 0.19 mg kg-1. Concentrations of Se in the samples collected in the superficial layers were positively correlated to cationic exchange capacity, as well as to clay, organic matter and oxide contents of the soils. In the subsurface samples, only pH and aluminum oxide content were correlated with Se concentrations. Most samples with the highest Se concentrations were derived from sedimentary parent material. Se(IV) adsorption was high for all soils, decreased with increasing pH and was strongly correlated to organic matter and Fe and Al oxides contents. On the other hand, Se(VI) adsorption was very low at pH values commonly found in agricultural soils, except for the highly weathered Rhodic Acrudox which was positively correlated with the gibbsite content. The constant capacitance model fit the Se(IV) and Se(VI) adsorption data well, and was similar to Langmuir and Freundlich empirical models. Optimizations of mono and bidentate complexation and surface protonation constant were used for the Se(IV) adsorption data. For Se(VI), optimizations for the two monodentate species were employed.
O selênio (Se) é um elemento traço essencial a nutrição animal. Por outro lado, o limiar de concentração entre suficiente e tóxico é estreito. A presença de Se nos alimentos está relacionada à sua concentração no solo. Deste modo, conhecer a quantidade e o comportamento do Se no solo é muito importante para um correto manejo ambiental, previnindo problemas toxicológicos e deficiência em humanos. Os objetivos deste estudo foram: (i) quantificar os conteúdos naturais de Se em solos brasileiros e correlacioná-los com seus atributos; (ii) avaliar a adsorção de selenito e selenato em função da variação do pH e da concentração de Se em solos tropicais; (iii) ajustar o modelo de capacitancia constante para descrever a adsorção de Se em solos tropicais comparado a modelos empíricos. As concentrações de Se variaram de <0,08 - 1,61 mg kg-1, com média de 0,19 mg kg-1. As concentrações de Se nas amostras coletadas nas camadas superficiais do solo foram positivamente correlacionadas com a capacidade de troca catiônica, bem como os teores de argila, matéria orgânica e óxidos de Fe e Al do solos. Nas amostras subsuperficiais, apenas pH e teor de óxido de alumínio foram correlacionadas com as concentrações de Se. A maioria das amostras com maiores concentrações de selênio foram provenientes de material de origem sedimentar. A adsorção de Se(IV) foi elevada para todos os solos, diminuiu com o aumento do pH e foi fortemente correlacionada com teores de matéria orgânica e de óxidos de Fe e de Al. Por outro lado, a adsorção de Se(VI) foi muito baixa em valores de pH normalmente encontrados em solos agrícolas, excepto para o Latossolo Vermelho acriférrico, que foi positivamente correlacionada com o teor de gibbsita dos solos. O modelo de capacitância constante ajustou-se bem aos resultados de adsorção Se(IV) e Se(VI), com ajuste similar aos modelos empíricos de Langmuir e de Freundlich. Para os resultados de adsorção de Se(IV) foram utilizadas otimizações das constantes de complexação mono e bidentadas e da constante de protonação de superfície. Para Se(VI), foram empregadas otimizações para as duas espécies de monodentadas.

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Garcia, Edder. "CO2 adsorption from synthesis gas mixtures : understanding selectivity and capacity of new adsorbents." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10195.

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Le développement de nouveaux adsorbants écologiques et efficaces pour la séparation du CO2 nécessite un lien quantitatif entre les propriétés des adsorbants et ses propriétés d'adsorption. Dans ce travail, nous développons une méthodologie qui prend en compte explicitement les propriétés des adsorbants, tels que le diamètre de pore, la densité, la forme de pore et la composition chimique. L'objectif est d'établir des corrélations quantitatives entre les paramètres mentionnés ci-dessus et les forces qui gouvernent la physisorption dans les milieux poreux, c'est à dire les interactions van der Waals et les interactions électrostatiques. Ainsi, les propriétés optimales des adsorbants pour la séparation du CO2 sont identifiées. En parallèle à ces études théoriques, une série d'adsorbants potentiellement intéressants pour la séparation du CO2 par PSA ont été testées expérimentalement. Une étude systématique de l'influence du centre métallique sur les séparations de mélanges CO2/CH4 et CO2/CH4/CO a été réalisée sur MOFs présentant sites coordinativement insaturés. Dans le cas des zéolithes, l'effet de la composition chimie (rapport Si / Al) sur les propriétés de séparation a été étudiés. Les capacités cycliques et des sélectivités ont été déterminées par des expériences de perçage. Les matériaux présentant un bon compromis entre la sélectivité et la capacité de travailler dans les conditions typiques de PSA ont été identifiés. Finalement, une comparaison entre la prédiction du modèle d'adsorption et les expériences a été faite
The design of new environmentally friendly and efficient adsorbents for CO2 separation requires a quantitative link between the adsorbent properties and adsorption capabilities. In this work we develop a methodology, which explicitly takes into account the adsorbent properties, such as the pore diameter, density, pore shape and chemical composition. The objective is to establish quantitative correlations between the above-mentioned parameters and the forces that govern physisorption in porous media, i.e. van der Waals forces and electrostatic interactions. Thus, the optimal properties of the adsorbent for CO2 separation are identified. In parallel to these theoretical studies, a series of potentially interesting adsorbents for CO2 separation by PSA were tested experimentally. A systematic study of the influence of the metal center on the separations of CO2/CH4 and CO2/CH4/CO mixtures was carried out on MOFs presenting coordinatively unsaturated sites. In the case of zeolites, the effect of the framework composition (Si/Al ratio) on the separation properties was studied. The cyclic capacities and selectivities were determined by breakthrough experiments. Materials presenting a good compromise between selectivity and working capacity under typical PSA conditions were identified. Finally, a comparison between the prediction of the adsorption model and the breakthrough experiments is carried out

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Annaduzzaman, Md. "Chitosan biopolymer as an adsorbent for drinking water treatment : Investigation on Arsenic and Uranium." Licentiate thesis, KTH, Mark- och vattenteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-167973.

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In many countries over the world (including Sweden), metal toxicity in freshwater resources causes a severe drinking water quality problem and poses a threat to the environment and human health. Among the different toxic metals in the water resources of Sweden, arsenic and uranium are the biggest threats to health. These elements, over long time consumption, may even lead to cancer and/or neurological disorder. Most of the wells are installed in crystalline and sedimentary bedrock and the received water comes from water bearing fractures in the bedrock. The handling of such water is an issue and there is a need to reduce the arsenic and uranium exposure by improving processes and technologies. It is a very serious problem demanding a safe, sustainable and eco-friendly arsenic and uranium removal technology prior to drinking water supply. Different treatment systems are available, but many of them are not suitable due to their high cost, operation complexity and waste management issues. Through this study, chitosan biopolymer the second largest abundant polysaccharide on earth after cellulose, was verified as a potential adsorbent for arsenic(V) and uranium(VI) removal from water solution. Adsorbent characterizations were also conducted by XRD, FTIR, SEM, UV-visible spectrum and TGA/DTA investigations. Bench-scale batch experiments were conducted using chitosan biopolymer (DDA-85%) as an adsorbent to determine the arsenic(V) and uranium(VI) removal efficiency, by allowing four important effective parameters e.g. chitosan dosages, pH, contact time and contaminant concentration. The adsorption data at optimum conditions were fitted with Langmuir, Freundlich and Dubinin-Radushkhevic (D-R) isotherm and Lagergren pseudo-first-order and pseudo-second-order kinetic model to investigate the adsorption process. The characterization of materials assured the presence of effective amino, hydroxyl, and carboxyl groups of chitosan. Another advanntage is that the materials are bio-degradable. The results show that the arsenic(V) and uranium(VI) removal efficiency was 100% and 97.45% after 300 minutes with optimum pH of 6.0 and 7.0 respectively. The optimum adsorbent dosages and initial concentration were 60 and 80g/L and 100 and 250 µg/L respectively. The adsorption process was suitably described by Freundlich isotherm (R2 = 0.9933) and Langmuir isotherm (R2 = 0.9858) correspondingly for arsenic(V) uranium(VI) compared to other isotherms. This is an important indicator of homogeneous monolayer adsorption of metals. For both of arsenic(V) and uranium(VI), pseudo-second-order explained the adsorption kinetics better than pseudo-first-order and the second-order kinetic regression coefficient (R2) were 0.9959 and 0.9672 correspondingly. Connecting to the above mentioned results, it can be summed up that the chitosan biopolymer (DDA 85%) can be used as an inexpensive, sustainable and environment-friendly treatment option for arsenic(V) and uranium(VI) contaminated drinking water.
I många länder världen runt (även i Sverige) orsakar metallers toxicitet besvärliga vattenkvalitetsproblem och utgör ett hot mot människors hälsa. Bland de toxiska metaller som finns i svenska vatten utgör arsenik och uran i dricksvatten allvarliga hälsorisker vid långvarig exposition då de kan orsaka cancer och neurologiska problem. Flertalet brunnar är installerade i kristallint berg och sedimentära bergarter och vattnet kommer vanligen från sprickor i berggrunden. Hanteringen av sådant vatten kan kräva reduktion av expositionen för arsenik- och uraninnehåll genom förbättrade processer och teknologier. Detta är ett angeläget problem som kräver en säker, pålitlig och ekovänlig teknologi att tillämpas innan vattnet distribueras. En rad olika behandlingssystem är tillgängliga men många av dem är inte lämpliga beroende på deras höga kostnad, den komplicerade tillämpningen och problem med hanteringen av restprodukter. I denna studie has biopolymeren chitosan, den näst vanligaste polymeren efter cellulosa, konstaterats vara en möjlig adsorbent för att avlägsna arsenik(V) och uran(VI) från vatten. Karakterisering av adsorbenten har också genomförts genom XRD, FTIR, SEM, UV och strålning i synligt ljus samt TGA/DTA undersökningar. Batch-tester i bänkskala har genomförts med användning av chitosan (DDA-85%) som adsorbent för att bestämma dess förmåga att avlägsna arsenik(V) och uran(VI)genom att variera fyra parametrar, nämligen kontakttid, pH, dos av chitosan och halt av föroreningen. Adsorptionsdata vid optimala förhållanden bestämdes genom tillämpning av Langmuir, Freundlich och Dubinin-Radushkhevic (D-R) isotermerna. Vidare tillämpades Lagergrens pseudo-first-order och pseudo-second-order kinetiska modell för att undersöka adsorptionsprocessen. Karakteriseringen av materialet visade förefintligheten av effektiva amino- (N-H), hydroxyl- (O-H) samt karboxylgrupper (C=O) i chitosan-polysackariden och att det är lätt nedbrytbart. Preliminära resultat visar att reduktionen av arsenik(V) och uran(VI) var 100 respektive 97,45 % efter 300 minuters kontakttid med optimalt pH på 6,0 respektive 7,0. De optimala doserna av adsorbent och den initiala koncentrationen var 60 och 80 g/L och 100 och 250 µg/L. Adsorptions process beskrevs bäst av Freundlich-isotermen för arsenik(V) (R2 = 0.9933) och med Langmuir-isotermen för uran(VI) (R2 = 0,9858) jämfört med andra isotermer vilket var en viktig indikation på en homogen monolager-adsorption. För både arsenik(V) och uran(VI) beskrev pseudo-second order adsorptionen bättre än pseudo-first-order. Second-order kinetiska regressionskoefficienten (R2) var 0.9959 och 0.9872 respektive. De ovanstående resultaten visar sammanfattningsvis att chitosan (DDA-85%) kan användas som en billig, pålitlig och miljövänlig behandlingsmetod av vatten för arsenik(V) och uran(VI).

QC 20150526

ChitoClean

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12

Tetteh, Emmanuel. "Adsorption of Pharmaceuticals and Endocrine Disrupting Compounds using Unmodified and Surfactant Modified Palygorskite-Montmorillonite Clay Particles in Batch and Fixed Bed Column Modes." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1543583842195458.

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13

Bonneau, Olivier. "Étude des effets physico-chimiques des superplastifiants en vue d'optimiser le comportement rhéologique des bétons à ultra-hautes performances." Cachan, Ecole normale supérieure, 1997. http://www.theses.fr/1997DENS0027.

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Les bétons de poudres réactives (BPR) forment une nouvelle génération de BUHP. Les bpr sont composes de poudres fines et sont caractérises par un faible rapport eau/ciment et une forte concentration en superplastifiant. Pour étudier l'interaction (ciment, fumée de silice, adjuvant), nous avons développé une méthode basée sur le découplage des effets de l'eau et de l'adjuvant sur la rhéologie. Dans le cas des bpr, il existe un optimum rhéologique en superplastifiant qui dépend fortement de la formulation. Un modèle de prédiction permet de calculer cet optimum avec seulement 4 paramètres définissant la composition du bpr. Des essais d'isothermes d'adsorption confirment le rôle de ces paramètres. Ainsi, la quantité d'adjuvant pour saturer les surfaces est proportionnelle au dosage conduisant au comportement rhéologique optimal. Les effets du superplastifiant sur la cinétique d'hydratation sont étudiés par l'intermédiaire de la conductivité électrique et de la puissance dissipée lors d'essais en mode isotherme. Nous avons mis en évidence une relation linéaire entre la conductivité électrique (#e#l#e#c) et le degré d'hydratation () : #e#l#e#c = av + bvx. Le terme BV est une caractéristique de l'empilement granulaire des bpr étudiés. Le seuil de percolation électrique peut être observé sur cette courbe, #e#l#e#c

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14

Jones, Jamie. "Chemophysical Characteristics and Application of Biosorption Activated Media (BAM) for Copper and Nutrient Removal in Stormwater Management." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5954.

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For high groundwater table areas, stormwater wet detention ponds are utilized as the preferred stormwater management throughout the state of Florida. Previous research has found that accumulations of nutrients, algae, heavy metals, pesticides, chlorophyll a, fecal coliform bacteria and low concentrations of dissolved oxygen (DO) are common characteristics of stormwater wet detention ponds. Although these pollutant levels are not regulated within the ponds, states are required to compute the pollutant load reductions through total maximum daily load (TMDL) programs to meet the water quality requirements addressed by the Clean Water Act (CWA). In this study, field sampling data of stormwater ponds throughout Florida are presented to identify concentration levels of the main contaminants of concern in the discharge of wet detention ponds. Sampling was done to identify possible sources, in addition to possible removal mechanisms via the use of specific sorption media. Nutrients were found as a main problematic pollutant, of which orthophosphate, total phosphorus, ammonia, nitrate, and total nitrogen were targeted whereas heavy metals exhibited minor concerns. Accumulation of high nutrient concentrations may be mitigated by the adoption of best management practices (BMPs) utilizing biosorption activated media (BAM) to remove phosphorus and nitrogen species through physical, chemical, and biological processes. This study aims to increase overall scientific understanding of phosphorus removal dynamics in sorption media systems via Langmuir and Freundlich isotherms and column studies. The removal of phosphorus (P) was proven effective primarily through chemophysical processes. The maximum orthophosphate adsorption capacities were determined under varying conditions of the media within the columns, which were found up to 0.000534 mg-P adsorbed per gram BAM with influent concentrations of 1 mg?L-1 orthophosphate in distilled water and 1 hour hydraulic residence time (HRT). When using spiked pond water under the same conditions, the adsorption capacity was increased about 30 times to 0.01507 mg-P?g-1 BAM presumably due to the properties and concentrations of ions affecting the diffusion rate regulating the surface orthophosphate reactions. These equilibrium media uptake values (q) were used to calculate the life expectancies of the media under varying HRT and influent concentrations of treatment. Chemophysical and biological removal capabilities of the media for total nitrogen, ammonia, and nitrate were effective in columns using 1100 g of BAM. In flow-through column conditions, ammonia had a consistent ~95% removal while effluent nitrate concentrations were highly variable due to the simultaneous nitrification-denitrification processes once an aerobic-anaerobic environment was established. Batch column experiments simulating no-flow conditions within a media bed reactor resulted in orthophosphate removals comparable with the continuous flow conditions, increased total phosphorus effluents indicative of chemical precipitation of orthophosphate, decreased ammonia removal, and increased nitrate removal. Due to a biofilm's sensitivity to even low copper concentrations and accumulation in ponds, a copper sorption media mix of “green” materials was generated. Freundlich and Langmuir isotherm tests concluded a successful mix resulting in copper removal efficiencies up to 96%.
M.S.
Masters
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Environmental Engineering; Environmental Engineering Sciences

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15

Lima, Camila Renata Machado de. "Estudos de adsor??o de tetraciclina e cromoglicato em part?culas de quitosana." Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17693.

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Made available in DSpace on 2014-12-17T15:42:04Z (GMT). No. of bitstreams: 1 CamilaRML_DISSERT.pdf: 3932876 bytes, checksum: 4cacf8f7fc64136e2ecb15a917a88b97 (MD5) Previous issue date: 2013-01-25
Universidade Federal do Rio Grande do Norte
Among the polymers that stand out most in recent decades, chitosan, a biopolymer with physico-chemical and biological promising properties has been the subject of a broad field of research. Chitosan comes as a great choice in the field of adsorption, due to their adsorbents properties, low cost and abundance. The presence of amino groups in its chain govern the majority of their properties and define which application a sample of chitosan may be used, so it is essential to determine their average degree of deacetylation. In this work we developed kinetic and equilibrium studies to monitor and characterize the adsorption process of two drugs, tetracycline hydrochloride and sodium cromoglycate, in chitosan particles. Kinetic models and the adsorption isotherms were applied to the experimental data. For both studies, the zeta potential analyzes were also performed. The adsorption of each drug showed distinct aspects. Through the studies developed in this work was possible to describe a kinetic model for the adsorption of tetracycline on chitosan particles, thus demonstrating that it can be described by two kinetics of adsorption, one for protonated tetracycline and another one for unprotonated tetracycline. In the adsorption of sodium cromoglycate on chitosan particles, equilibrium studies were developed at different temperatures, allowing the determination of thermodynamic parameters
Dentre os pol?meros que mais se destacam nas ?ltimas d?cadas, a quitosana, um biopol?mero com propriedades f?sico-qu?micas e biol?gicas promissoras, tem sido alvo de um campo amplo de pesquisa. A quitosana se apresenta como uma ?tima escolha no campo de adsor??o, devido a suas propriedades adsorventes, baixo custo e abund?ncia. A presen?a de grupos aminos em sua cadeia governam a maioria das suas propriedades e definem em qual aplica??o dada amostra de quitosana poder? ser utilizada, assim torna-se imprescind?vel a determina??o do seu grau de desacetila??o m?dio. Neste trabalho foram desenvolvidos estudos cin?ticos e de equil?brio a fim de monitorar e caracterizar o processo de adsor??o de dois f?rmacos, o cloridrato de tetraciclina e o cromoglicato de s?dio, em part?culas de quitosana. Modelos cin?ticos e de isotermas de adsor??o foram aplicados nos dados experimentais. Para ambos os estudos, an?lises no potencial zeta tamb?m foram realizadas. A adsor??o de cada f?rmaco apresentou aspectos distintos. Atrav?s dos estudos desenvolvidos neste trabalho foi poss?vel descrever um modelo cin?tico para a adsor??o de tetraciclina em part?culas de quitosana, demonstrando que o mesmo pode ser descrito por duas cin?ticas de adsor??o, uma para a tetraciclina protonada e outra para a tetraciclina n?o protonada. Na adsor??o de cromoglicato de s?dio em part?culas de quitosana, estudos de equil?brio foram desenvolvidos a diferentes temperaturas, permitindo a determina??o de par?metros termodin?micos

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Okon, Edidiong. "Preparation, characterization and carrier gas transport characteristics of inorganic and organic membranes for application in lactic acid esterification with ethanol." Thesis, Robert Gordon University, 2018. http://hdl.handle.net/10059/3123.

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Ethyl lactate (EL) plays a major role as green solvent and also a replacement for most petrochemical solvents. The esterification process of lactic acid and ethanol to produce EL is an equilibrium-limiting reaction and the selective removal of one of the reaction products can be improved using a membrane reactor and when coupled with a heterogeneous catalyst offers an opportunity for process intensification. This thesis investigates the batch process esterification reaction involving lactic acid (LA) and ethanol (EL) in the presence of a water selective membrane using different cation-exchange resin catalysts. The product was analysed using gas chromatograph coupled with mass spectrometry detector (GC-MS). The analytical methods used for the characterisation of the cation-exchange resins and membrane include Fourier transform infrared coupled with attenuated total reflectance (FTIR-ATR), scanning electron microscopy attached to energy dispersive analyser (SEM/EDAX), Liquid nitrogen physisorption and nuclear magnetic resonance (NMR) respectively. A novel method was developed for carrying out esterification reaction in a gaseous phase system using a flat sheet polymeric membrane. Prior to the esterification reaction, different carrier gases were tested with ceramic membrane to determine the suitable carrier gases for the analysis of esterification product. The four carrier gases used for the permeation test were argon (Ar), helium (He), carbon dioxide (CO2) and nitrogen (N2). A 15nm pore size commercially available tubular ceramic support, consisting of 77%Al2O3 and 23%TiO2 with the porosity of 45% was used for the carrier gas investigation. The support was modified with silica based on the sol-gel dip-coating techniques. The dip-coated membrane exhibited a higher molar flux with He (0.046mol m-2s-1) and Ar (0.037mol m-2s-1) with a much lower flux for N2 (0.037mol m-2s-1) and CO2 (0.035 mol m-2s-1) at 0.30 bar. Helium gas with the highest permeation rate were identified as the suitable carrier gas for the analysis of esterification product with GC-MS. The esterification reaction in the presence of four cation-exchange resins to produce ethyl lactate was carried out between 60-160 oC in a batch and membrane processes to determine the effectiveness resin catalysts for LA esterification. The effect of external mass transfer diffusion limitation between the liquid components and the resin catalysts was avoided by increasing the agitation time of the esterification reaction. The percentage conversion rate of the lactic acid feed from the batch process esterification was found to be in the range of 98.6 to 99.8%. The reaction kinetics of the esterification reaction was described based on two simplified mechanisms of Langmuir Hinshelwood model to describe the adsorption components on the surface of the catalysts. The lactic acid feed gave a conversion rate of up to 100 % confirming the effectiveness of the acetate membrane impregnated resin catalysts in the selective removal of water for the separation of ethyl lactate. The significance of producing ethyl lactate through batch process intensified by a water-selective membrane processes can be recommended for industrial LA production.

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17

Surasani, Vikranth Kumar. "A non-isothermal pore network drying model." Magdeburg Docupoint-Verl, 2008. http://d-nb.info/992455790/04.

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18

Caroni, Ana Luiza Porpino Fernandes. "Estudos de adsor??o de tetraciclina em part?culas de quitosana." Universidade Federal do Rio Grande do Norte, 2009. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17701.

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Due to its physico-chemical and biological properties, related to the abundance and low cost of raw material, chitosan has been recognized as a material of wide application in various fields, such as in drug delivery systems. Many of these properties are associated with the presence of amino groups in its polymer chain. A proper determination of these amino groups is very important, in order to properly specify if a given chitosan sample can be used in a particular application. Thus, in this work, initially, a comparison between the determination of the deacetylation degree by conductometry and elemental analysis was carried out using a detailed analysis of error propagation. It was shown that the conductometric analysis resulted in a simple and safe method for the determining the degree of deacetylation of chitosan. Subsequently, experiments were performed to monitor and characterize the adsorption of tetracycline on chitosan particles through kinetic and equilibrium studies. The main models of kinetics and adsorption isotherms, widely used to describe the adsorption on wastewater treatment systems and the drug loading, were used to treat the experimental data. Firstly, it was shown that an apparent linear t/q(t) ? t relationship did not imply in a pseudo-second-order adsorption kinetics, differently of what has been repeatedly reported in the literature. It was found that this misinterpretation can be avoided by using non-linear regression. Finally, the adsorption of tetracycline on chitosan particles was analyzed using insights obtained from theoretical analysis, and the parameters generated were used to analyze the kinetics of adsorption, the isotherm of adsorption and to ropose a mechanism of adsorption
Devido ?s suas propriedades f?sico-qu?micas e biol?gicas, associadas ? abund?ncia e ao baixo custo da mat?ria-prima, a quitosana tem sido considerada um material de ampla aplica??o em diversos campos, tais como em sistemas de libera??o de f?rmacos. Muitas dessas propriedades est?o associadas ? presen?a de grupos amino em sua cadeia polim?rica. Uma determina??o apropriada desses grupos amino ? muito importante, com o objetivo de especificar adequadamente se uma dada amostra de quitosana pode ser usada em uma particular aplica??o. Dessa forma, neste trabalho, inicialmente, foi realizada uma compara??o entre a determina??o do grau m?dio de desacetila??o atrav?s de an?lises condutim?trica e elementar usando uma minuciosa an?lise de propaga??o erro. Foi mostrado que a an?lise condutim?trica resultou em um m?todo simples e seguro para determina??o do grau m?dio de desacetila??o da quitosana. Posteriormente, foram realizados experimentos a fim de monitorar e caracterizar o processo de adsor??o de tetraciclina em part?culas de quitosana, atrav?s de estudos cin?ticos e de equil?brio. Os principais modelos cin?ticos e de isotermas de adsor??o, amplamente usados para descrever a adsor??o em sistemas de tratamento de efluentes e de incorpora??o de f?rmacos, foram utilizados nos dados experimentais. Primeiramente, foi mostrado que uma aparente rela??o linear t/q(t) ? t n?o implica em um mecanismo de adsor??o de pseudo-segunda-ordem, diferentemente do que tem sido repetitivamente relatado na literatura. Foi encontrado que esta interpreta??o err?nea pode ser evitada atrav?s do uso de uma regress?o n?o-linear. Finalmente, a adsor??o de tetraciclina em part?culas de quitosana foi analisada, utilizando os conhecimentos obtidos de uma an?lise te?rica, e os par?metros gerados foram usados para analisar a cin?tica de adsor??o, a isoterma de adsor??o e para propor um mecanismo de adsor??o

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19

Galloway, Conner Daniel (Conner Daniel Cross). "Isothermal model of ICF burn with finite alpha range treatment." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53296.

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Thesis (S.M. and S.B.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2009.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 67).
A simple model for simulating deuterium tritium burn in inertial confinement fusion capsules is developed. The model, called the Isothermal Rarefaction Model, is zero dimensional (represented as ordinary differential equations) and treats disassembly in the isothermal limit. Two substantive theoretical developments are contained in this model; one is an improved treatment of fast alpha slowing down, and the other is a calculation of the fusion product source distributions and their energy moment. The fast alpha stopping treatment contains a derivation of the Fraley fractional energy splitting functional form, fe = 1/(1 + xTe), resulting in an expression for the numerical factor x which will be defined as the Fraley parameter. The average thermal energy which is lost from the thermal ion distribution when two particles fuse is found from the energy moment of the fusion product source distribution. This energy contributes to the energy of the fusion products. A third theoretical development that is discussed for completeness and future use, but not yet incorporated in the Isothermal Rarefaction Model, is the 4T theory of matter-radiation energy exchange in homogenous optically thick media. The isothermal rarefaction model assumes an optically thin to marginally thick plasma, and only Bremsstrahlung emission and absorption are treated in this thesis. The 4T theory for optically thick media has been published. A sampling of results using the Isothermal Rarefaction Model is presented.
by Conner Daniel Galloway.
S.M.and S.B.

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Herrán, Fernando. "Validation, improvement and implementation of sorption mathematical models using a quartz crystal microbalance (QCM)." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10063.

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Ce travail de thèse a été réalisé, dans le cadre de la convention CIFRE 1538/2010, au sein d'adixen Vacuum Products (aVP) à Annecy (France). Il a été en partie financé par le projet S.P.A.M. (Surface Physics for Advanced Manufacturing). Il s'agit d'un projet ITN financé par le programme Pierre et Marie Curie de la Communauté Européenne rassemblant des partenaires universitaires et industriels dont aVP. L'objectif de ce programme était de contribuer à l'étude et au développement de la lithographie et en particulier la lithographie à ultraviolet extrême (EUVL). Ce travail porte sur la problématique de la contamination moléculaire dans l'industrie des semi-conducteurs ainsi que les besoins de maitrise de contamination pour la photolithographie EUVL. Pour ce faire, des modèles mathématiques de sorption ont été recherchés, testés et validés à l'aide d'une microbalance à quartz (QCM). Cette technique, possédant une très haute sensibilité (au niveau du ng), permet d'étudier les phénomènes de sorption relatifs à tout matériau déposable sur un cristal de quartz mis au contact de différents gaz dont la pression partielle est maitrisée. Par conséquent, le protocole détaillé dans cette thèse peut être utilisé pour d'autres types d'expériences dans toute discipline nécessitant une telle précision. Le déroulement de notre plan d'expérience comprend deux types de matériaux naturellement différents : un polymère (PCBA) d'une part et deux substrats métalliques (SS AISI 304 et CuC1) d'autre part pour lesquels le transfert de masse n'intervient pas de la même manière. Les gaz d'étude ont été sélectionnés pour leur intérêt dans l'industrie des semi-conducteurs (vapeur d'eau, HF). Le résultat de l'interaction des gaz d'étude avec les substrats ciblés est suivi en direct par la QCM, ce qui permet non seulement de valider et/ou améliorer les modèles mathématiques déjà disponibles dans la bibliographie mais aussi de les ajuster aux données obtenues expérimentalement. Nous pouvons ainsi non seulement prévoir le comportement des contaminants à l'équilibre (isothermes) et à l'état transitoire mais aussi réaliser des estimations de sorption à des températures autres que celles retenues pour notre plan d'expérience
This thesis was carried out within the framework of the CIFRE 1538/2010 convention at adixen Vacuum Products (aVP) in Annecy (France). It is has been partly funded by the ITN project SPAM (Surface Physics for Advanced Manufacturing). SPAM is an ITN project funded by the Pierre and Marie Curie program of the European Community bringing together academic institutions and industrial partners including aVP. The objective of this program was to contribute to the study and development of lithography and extreme ultraviolet lithography (EUVL). This work deals with the issues caused by the airborne molecular contamination (AMC) in the semiconductor industry and their control needs in EUVL and the current photolithography. In order to tackle the problem, sorption mathematical models have been investigated and validated using a quartz crystal microbalance (QCM). This technique, which confers a high sensitivity (ng level), allows the study of the sorption phenomena related to any deposable material onto a quartz crystal in contact with different gases whose concentrations are accurately controlled. Consequently, the protocol detailed in this thesis may be used for other types of experiments in any discipline requiring such precision. The conduct of our experimental plan includes two types of naturally different materials: a polymer (PCBA) on the one hand and two metallic substrates (stainless steel AISI 304 and CuC1) on the other hand, for which the matter transfer does not occur in the same manner. Studied gases were selected for their interest in the semiconductor industry (water vapor, HF). The resulting interaction between the studied gases and the targeted substrates is continuously followed by the QCM, which allows not only to validate the mathematical models already proposed by the literature but also to fit the experimentally obtained data. This enables us not only to predict the behavior of the AMC at equilibrium (isotherms) and the transient state but also to provide sorption estimations at temperatures other than those specified in our experimental plan

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21

He, Liming. "Adsorption of sulfate and phosphate at the mineral-water interface: isotherm, stoichiometry, and models." Diss., Virginia Tech, 1995. http://hdl.handle.net/10919/40310.

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Processes occurring at mineral-water interfaces play critical roles for regulating the composition of surface and groundwater, for soil development, and for the availability of plant nutrients. Sulfate adsorption at three pH levels was conducted on y-AI203 and kaolinite. The adsorption isotherms were described well by the simple Langmuir, two-site Langmuir, Freundlich, and Temkin equations. The capacity of SO42-adsorption for y-AI203 was five times greater than for kaolinite, indicating the difference in reactive site density between y-Ab03 and kaolinite. Mathematical analyses for the adsorption isothenns demonstrated that S042- may not be adsorbed on the d-plane, i.e., in the diffuse layer, whereas both outer- and inner-sphere complexation mechanisms predicted S042- adsorption equally well.
Ph. D.

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22

Carabin, Pierre. "A numerical investigation of the isothermal and nonisothermal shrinking core model /." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56786.

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The shrinking core model, including the effect of transient diffusion, non-linear kinetics and non-isothermal effects was solved using finite elements in space and finite differences in time. The method of solution proposed by Murray and Carey was used with some modification to include an adjustable time step.
The solution for the first order isothermal case agreed well with the well-known pseudo steady state solution, within the conditions defined by Bischoff. At high dimensionless bulk concentration, the solution differed from the pseudo steady state especially at high Damkohler number (Da $>$ 10) where diffusion was dominating.
In the non-linear kinetics case, the effect of reaction order was minimal at high values of the Damkohler number, where diffusion limitations minimized the effect of reaction order. The critical parameters such as the dimensionless heat of reaction above which non-isothermal kinetics effects dominate were also determined.

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23

Steele, Benjamin (Benjamin Craig). "A computational model for the isothermal assembly of tiled DNA nanostructures." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/87467.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Biology, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 47-49).
Complex DNA nanostructures have proven difficult to assemble from starting materials. Inefficient nanostructure assembly constitutes a barrier to the widespread use of DNA nanotechnology and is difficult to investigate experimentally due to the complicated nature of the assembly. This work introduces a type of tile assembly model, the isothermal tile assembly model (iTAM). The iTAM seeks to capture the behavior of assembling DNA tile nanostructures to identify design factors and reaction conditions which improve assembly yields. Simulations using the iTAM model explain the experimental observation that only a narrow range of temperatures permit optimal isothermal assembly of tile-based DNA nanostructures. This narrow temperature range reflects a balance between the stabilization of non-designed interactions at low temperatures and the destabilization of the overall designed structure at high temperature. Simulations based on the iTAM are effective at estimating the temperature of optimal assembly unique to 25 two-dimensional tile designs, with an mean error of estimation of 4.6 degrees C. Results from the iTAM indicate that optimal assembly temperatures are determined largely by the strength of tile-tile domain interactions. For a given tile design, tile concentration and the length of time represent convenient axes of control over tile assembly. Kinetic trapping that blocks complete assembly of a tile design is likely to be overcome by increasing the both temperature and tile concentration in the assembly reaction. Such a change also substantially decreases the computationally predicted time required for complete assembly.
by Benjamin Steele.
S.M.

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Fike, Wonae Bong. "Sorption of Cadmium, Copper, Lead, and Zinc as influenced by pH, ionic strength and selected soil components." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/29430.

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Metals sorption in soils is influenced by several factors, including pH, ionic strength, the presence of ionic composition or organic ligands, total amount of metals, and adsorbent loading. These conditions should be considered when evaluating metal sorption capacity of soil material or when applying laboratory results to field conditions. Metal sorption experiments were conducted on Bertie sandy and Starr-Dyke clay loam soils from long-term field studies in which soils received annual applications of copper-rich pig manure for 16 years. Adsorption of Cd, Cu, Pb, and Zn as affected by different background electrolytes at various concentrations was investigated. Electrolytes were Na+, Ca2+, or Al3+ in perchlorate solution, and their concentrations ranged from 0.001 to 0.5 molc L-1. Increasing ionic strength decreased metal adsorption capacity. Electrolyte cation composition had a greater effect on adsorption than did electrolyte concentration. The order of sensitivity to cation composition of the electrolyte was Zn > Cd > Cu > Pb, and this effect was greater in Bertie sandy loam than Starr-Dyke clay loam soils. Little difference in Cu and Pb adsorption was observed between Na+ and Ca2+ in background solution. Most added Cu was adsorbed at low concentrations regardless of pH, but at high concentrations Cu sorption was strongly related to solution pH. Increases in pH resulted in greater Cu sorption due to pH-dependent negative charges and precipitation. The USEPA recommends that soil systems receiving high metal loading rates be maintained at pH 6.5 or above because of the increased metal adsorption. However, pig manure applications to the Bertie soil resulted in greater Cu in soil solution than in control (no manure) soil at pH > 6.5 due to soluble organic matter. Using the Langmuir equation to determine adsorption maxima for soil systems does not always give adequate estimates of adsorption and values from the equations are highly dependent upon soil environmental parameters. Given the limitations in prediction of adsorption maxima, and given that the amount of nonsorbed metal is as important as the adsorbed amount, the isolines of metal remaining in soil solution were provided with a given set of soil environmental factors.
Ph. D.

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Jindra, Daniel. "Stanovení požární odolnosti konstrukcí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392030.

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Possibilities of modeling non-linear behavior of concrete within standard room temperatures and increased fire-load values using FEM software ANSYS are studied. Temperature dependences of material models are considered. Fire resistance of reinforced concrete and concrete-steel composite construction is analyzed. Fire loads are defined in accordance with relevant standards. Non-linear structural transient analyses are calculated after temperatures were determined by transient thermal analyses. Results obtained from analyses of simple reinforced concrete structure are compared with approach of isotherm 500 °C method.

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Fechtner, Marcus Verfasser], and Achim [Gutachter] [Kienle. "Model-based analysis of chromatographic processes with implicit sorption isotherms / Marcus Fechtner ; Gutachter: Achim Kienle." Magdeburg : Universitätsbibliothek Otto-von-Guericke-Universität, 2020. http://d-nb.info/1225863333/34.

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Fechtner, Marcus [Verfasser], and Achim [Gutachter] Kienle. "Model-based analysis of chromatographic processes with implicit sorption isotherms / Marcus Fechtner ; Gutachter: Achim Kienle." Magdeburg : Universitätsbibliothek Otto-von-Guericke-Universität, 2020. http://d-nb.info/1225863333/34.

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28

Schmittbiel, Jean-Marc. "Modes de recristallisation après forgeage isotherme d'un superalliage élaboré par métallurgie des poudres." ENSMP, 1996. http://www.theses.fr/1996ENMP1006.

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Soma, Shu. "Experimental and Theoretical Study on Enhancing Effect of Capillary Evaporation." Kyoto University, 2020. http://hdl.handle.net/2433/253276.

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30

Vorhauer, Nicole. "Experiment based development of a non-isothermal pore network model with secondary capillary invasion." Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0082/document.

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Dans cette thèse, des simulations PN de séchage sont comparées à des données expérimentales obtenues dans le séchage d´un réseau de micro-fluidique 2D représentatif dans du SiO2 soumis à des conditions thermiques variables dans le but d’identifier les phénomènes physiques à l´échelle des pores qui sont les plus influents. A partir de cette étude, un PN efficace non-isotherme est développé. Ce modèle incorpore i) les phénomènes associés à la dépendendence en température de l´invasion à l´échelle des pores, c´est à dire l´invasion capillaire sous effet thermique et le flux de vapeur ainsi que ii) le transport secondaire induit par d´épais films liquides observé dans les expériences de microfluidique. Cette étude prouve clairement que le comportement macroscopique du séchage est fondamentalement dirigé par le gradient de température imposé sur le PN ainsi que par le transport capillaire secondaire. En accord avec la littérature, les schémas d´invasion que l´on trouve dans l´invasion percolatrice avec l´évaporation progressive d´amas individuels sont observés dans le séchage à variation de température locale négligeable;des gradients où la température diminue à partir de la surface (gradient de température négatif)peut stabiliser le front de séchage, qui évolue entre la phase gazeuse invasive et la phase liquide qui recule, alors qu´une température qui augmente à partir de la surface (gradient de température positif) amène à la déstabilisation de la phase liquide avec une percée prématurée de la branche gazeuse et l’initiation d´un deuxième front de séchage qui migre dans la direction opposé de celle du front de séchage original. Une attention particulière est prêtée aux régimes distincts que l´on trouve dans le second cas (gradient positif) parce qu´ils sont associés à différents procédés d´invasion à l´échelle des pores. Plus précisément, la dépendance en température de la tension de surface établit l´ordre d´invasion tant que la phase liquide est connectée au groupe liquide principal (que l´on trouve généralement pendant la première période de séchage). En revanche,l´étude détaillée des mécanismes de transfert de la vapeur met l´accent sur le fait que la diffusion de la vapeur à travers la région partiellement saturée peut contrôler les distributions des phases gazeuses et liquides à l´échelle des pores pendant la période de séchage lorsque la phase liquide est déconnectée en petits groupes. Cela est aussi lié à la croissance des amas induite par la condensation partielle de la vapeur. Cette thèse montre et discute en détail que cet effet ne dépend pas seulement de la direction et magnitude du gradient de température pour une distribution de tailles de pores donnée mais qu’en plus le taux d´évaporation influence le mécanisme de croissances des amas. Cela indique que la migration du liquide pendant la phase de séchage de milieux poreux peut être contrôlé par l’interaction des gradients thermiques et du taux de séchage. En somme, l´étude du séchage sous effet thermique des réseaux de pores 2D révèle des phénomènes complexes à l´échelle des pores, généralement aussi anticipés dans le séchage des milieux poreux réels. Cela mène au développement d´un modèle mathématique efficace au niveau des pores basés sur des découvertes expérimentales. Cette thèse démontre la manière dont ce modèle peut être appliqué afin de comprendre et développer des procédés de séchage modernes basés sur la simulation du transfert de masse sous effet thermique à l´échelle des pores
In this thesis, PN simulations of drying are compared with experimentally obtained data fromdrying of a representative 2D microfluidic network in SiO2 under varying thermal conditions withthe aim to identify governing physical pore scale effects. Gravity and viscous effects aredisregarded in this thesis. Instead drying with slight local temperature variation and drying withimposed thermal gradients are studied. Based on this investigation, a powerful non-isothermalPNM is developed. This model incorporates i) the phenomena associated with the temperaturedependency of pore scale invasion, namely thermally affected capillary invasion and vapor flow aswell as ii) the secondary effects induced by wetting liquid films of different morphology. This studyclearly evidences that the macroscopic drying behavior is fundamentally dictated by thetemperature gradient imposed on the PN and moreover by the secondary capillary invasion aswell. In agreement with literature, invasion patterns as in invasion percolation with progressiveevaporation of single clusters are observed in drying with negligible local temperature variation;gradients with temperature decreasing from the surface (negative temperature gradient) canstabilize the drying front, evolving between the invading gas phase and the receding liquid phase,whereas temperature increasing from the surface (positive temperature gradient) leads todestabilization of the liquid phase with early breakthrough of a gas branch and initiation of asecond invasion front migrating in opposite direction to the evaporation front receding from theopen surface of the PN. Special attention is paid on the distinct drying regimes found in thesituation of a positive gradient because they are associated with different pore scale invasionprocesses. More precisely, temperature dependency of surface tension dictates the order ofinvasion as long as the liquid phase is connected in a main liquid cluster (usually found during thefirst period of drying). In contrast to this, detailed study of the vapor transfer mechanismsemphasizes that vapor diffusion through the partially saturated region can control the pore leveldistributions of liquid and gas phase during the period of drying when the liquid phase isdisconnected into small clusters. This is also related to the cluster growth induced by partialcondensation of vapor. It is shown and discussed in detail in this thesis that this effect not onlydepends on direction and height of the temperature gradient for a given pore size distribution butthat moreover the overall evaporation rate influences the cluster growth mechanism. This indicatesthat liquid migration during drying of porous media might be controlled by the interplay of thermalgradients and drying rate. In summary, the study of thermally affected drying of the 2-dimensionalPN reveals complex pore scale mechanisms, usually also expected in drying of real porous media.This leads to the development of a strong mathematical pore scale model based on experimentalfindings. It is demonstrated how this model might be applied to understand and develop moderndrying processes based on the simulation of thermally affected pore scale mass transfer

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31

Carroni, Richard. "Investigation and validation of a cubic turbulence model in isothermal and combusting flows." Thesis, Loughborough University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311063.

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Schaffer, Joseph F. "Verification and Adaptation of an Infiltration Model for Water at Various Isothermal Temperature Conditions." Digital WPI, 1999. https://digitalcommons.wpi.edu/etd-theses/1061.

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"A series of one dimensional horizontal infiltration experiments were performed to investigate the predictive capabilities of the Kao and Hunt model. By modifying pristine laboratory apparatus, a reasonable range of soil temperatures was achieved. Experiments were run at approximately 5Â°C, 20Â°C, and 35Â°C. Distilled water was used as an infiltrating liquid and silica powder was used as soil. The infiltrating liquid was dispensed into the column at zero pressure head. The results of the experiments show that the model is adaptable to a range of temperature conditions by modifying terms for the liquid effects of the model, viscosity and surface tension. Experimental data and model predictions differed by 30 percent at most. Although the change in the rate of infiltration across the range of temperatures is perceivable, it is small in comparison to the effects caused by heterogeneity encountered in nature. "

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33

Quinn, Ruth. "Evaluation of flow models and pollutant retention isotherms for their application to rain garden bioretention." Thesis, University of Greenwich, 2015. http://gala.gre.ac.uk/14319/.

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The primary aims of this research was firstly to develop a computer modelling tool which could predict pollution retention in a rain garden and secondly to use the model and additional experiments to examine various aspects of rain garden design with respect to pollutant retention. Initially, the behaviour of all contaminants in urban runoff was examined including their retention and possible modelling methods. Heavy metals were then identified as the main focus of this project as this choice was the most beneficial addition to current research. The main factors affecting their retention were found to be macropore flow, pore water velocity, soil moisture content and soil characteristics and the primary method of modelling capture was identified as a sorption isotherm. Thus a dual-permeability heavy metal sorption model was developed; this was based on an intensive literature review of current best practice in both hydrological modelling and pollutant retention fields with respect to rain garden devices. The kinematic wave equation was chosen to model water movement in both the matrix and macropore regions as this provided a simpler alternative to more complex equations while still maintaining good accuracy. With regards to the modelling of heavy metal retention three isotherms were chosen: the linear, Langmuir and Freundlich equations as these were found from previous research to be the most accurate. These isotherms were incorporated into a one dimensional advection-dispersion-adsorption equation in order to model both transport and retention together. This model was tested against the appropriate literature and accurate comparisons were obtained thus validating it. Column experiments were designed to both provide a unique contribution to rain garden research and further validate the model. This was achieved by analysing past experiments and identifying an area where research is lacking; this area was the effect of macropore flow on heavy metal retention in rain garden systems under typical English climatic conditions. The findings of these experiments indicated that although macropore flow did not impact the hydraulic performance of the columns, retention of the most mobile of heavy metals, copper, was decreased slightly in one case. The overall retention of the columns was still high however at a value in excess of 99% for copper, lead and zinc. The results of the experiments were also used to further validate the model. The model was then applied to the development of a rain garden device for a planned roundabout in Kent, U.K. Preliminary design considered an upper root zone layer with organic soil and a sandy storage sublayer each 30 cm thick, for a rain garden area of 5 and 10% the size of the contributing impervious surface. Two scenarios were examined; the accumulation and movement of metals without macropores and the possibility of groundwater contamination due to preferential flow. It was shown that levels of lead can build up in the upper layers of the system, but only constituted a health hazard after 10 years. Simulations showed that copper was successfully retained (no significant concentrations below 50 cm of rain garden soil depth). Finally given concerns of preferential flow bypassing sustainable drainage systems, macropore flow was examined; results indicated that due to site conditions it was not a threat to groundwater at this location for the time frame considered. These actions successfully completed the objectives of this project and it was deemed successful.

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34

Esmele, Myles. "A model for deformation of continuous fiber composites under isothermal creep and thermal cycling conditions." Monterey, Calif. : Naval Postgraduate School, 1997. http://handle.dtic.mil/100.2/ADA363934.

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Richardson, Brian Ross. "A reduced-order model based on proper orthogonal decomposition for non-isothermal two-phase flows." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2623.

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Perchanok, Mathias Samson. "Isothermal scale model study of the gas flow field in a hog fuel boiler furnace." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28510.

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Good combustion is required to maximize steam generation and avoid emissions in the wood waste fired boilers found frequently in the pulp and paper industry. The combustion process is assisted if velocities above the grate are minimized, if gases in the combustion zone are mixed intimately, and if gaseous combustion is concentrated above the grate. A 1/15 scale replica of a power boiler was constructed for isothermal flow modelling of the flow field above the grate, the overfire air jets and the furnace up to the generating banks. The flow was made visible with smoke, and velocities were measured with a pulsed wire anemometer. It was found that a very non uniform velocity profile occurred above the fuel grate because the under grate plenum did not adequately diffuse the under grate air flow. Also, non perforated areas of the fuel grate near the furnace walls caused recirculation zones to occur above the grate near the front wall. The recirculation zones of the overfire air jets caused high velocities to occur above the grate as well. A large space between the front wall and the front overfire air nozzles on the side walls, caused vertical stratification of the flow, in which gases rising from the grate, near the front wall did not mix with the overfire air. At part load, reduced velocity in the overfire air jets caused vertical stratification of the flow as well, in which mixture of gases rising from the grate and overfire air occurred well above the fuel grate. At high nozzle velocities, gases were well mixed, throughout the cross section, large recirculations occurred and mixing was concentrated near the fuel grate. Established models for jets for free turbulent jets do not accurately represent opposing banks of jets. Centerline velocity is overpredicted by a factor of two or more, and deflection of the jet are greatly underpredicted by the models. Throw and penetration, calculated with the models do not give reasonable predictions, indicating the need for more sophisticated models. At high overfire air flow rates, oscillation of the overfire air jets was observed, with a period in the order of one second.
Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate

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37

Boughanim, Fouad. "Etude des écoulements isothermes et non isothermes des fluides non newtoniens : loi de carreau, loi de puissance." Saint-Etienne, 1996. http://www.theses.fr/1996STET4006.

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Dans ce travail, nous nous sommes intéressés au comportement asymptotique des écoulements tridimensionnels isothermes et non-isothermes des fluides non-newtoniens dans des domaines de faible épaisseur. Nous considérons d'abord un écoulement isotherme dont la viscosité suit le modèle de carreau ; on établit un théorème de convergence pour la vitesse et la pression quand l'épaisseur du domaine tend vers zéro. On fait apparaitre des valeurs critiques pour le nombre de Reynolds et nous donnons une condition faisant intervenir celui-ci et l'épaisseur du domaine pour que les approximations d'Hele-Shaw soient valables. Nous avons également étudié le comportement asymptotique d'un problème tridimensionnel où l'équation du mouvement est couplée avec une équation de type convection-diffusion et où la viscosité est donnée comme produit de la loi de puissance et de la loi d'Arrhenius. Nous obtenons dans ce cas un modèle limite découplé donné par une loi de type Poiseuille bidimensionnelle non-linéaire. La partie numérique de ce travail consiste à valider la loi limite obtenue dans le cas d'un écoulement non-isotherme. Nous utilisons pour cela une méthode d'éléments finis

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Kay, E. D. "A depth-averaged model for non-isothermal rimming flow driven at the surface by droplet impact." Thesis, University of Nottingham, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.664268.

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Driven by an application to the combined cooling and lubrication by oil of an aero-engine bearing chamber the research in this thesis studies non-isothermal thin liquid film flow on the inside of a circular cylinder driven at its surface by an air-shear and interfacial flux of liquid droplets. Flow conditions inside the bearing chamber preclude using classical lubrication theory models since these neglect some of the physical effects, specifically inertia and heat convection, which are important to this problem. To this end a depth-averaged approach, based on hydraulics modelling within a lubrication theory framework, is adopted which ensures all the relevant physical mechanisms are retained in the model for the film. In limiting cases the model is shown to be consistent with published models for thin film rimming flow. Leading-order inertial effects were found to extend the range of possible thin-film solutions beyond those predicted by lubrication theory alone. This can allow a smooth progression in solution from low-inertia cases, where the film may feature recirculations and steep-fronts, to high-inertia cases of uniform film flow as the film Reynolds number is increased. The accuracy of the depth-averaged model for film temperature is examined for the case of uniform film flow over a heated flat plate. Here an analytical solution exists and the model is found to give very good agreement with this. Film dynamics and thermal characteristics of the film, in particular those relating to the interfacial mass flux of droplets, are analysed in detail. The depth-averaged model is used to provide insight into the motivating bearing chamber application through calculation of oil film temperature characteristics and a parameter space showing the dependence of film residence times on chamber operating conditions.

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Grauer, Diana Kathryn. "Simulation and optimization of non-isothermal compressible flow through large-bore two-stroke cycle natural gas transmission engines." Diss., Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4230.

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40

Peterson, Anthony D. "Nonlinear Spectroscopic Investigation of Adsorption to C-18 Model Stationary Phase." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3888.

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Reversed-phase liquid chromatography (RPLC) is a commonly used separation technique in chemistry. Nevertheless, the mechanistic interactions at the molecular level among the eluent, analyte, and the stationary phase are not fully understood. Because of this limited understanding, optimization of the separation must be done experimentally. Learning more about molecular interactions should aid in improving separations. We are currently using second-harmonic generation (SHG) spectroscopy to investigate how analytes adsorb to the surface. SHG is a spectroscopic technique that produces signal only at places of non-isotropic symmetry; this typically occurs at surfaces. SHG can be used to produce surface isotherms of test analytes adsorbed to a model C18 stationary phase surface. Fitting these isotherms with a Langmuir model produces an adsorption equilibrium constant. However, the equilibrium constant can only be accurately determined if the true bulk concentration is known; this thesis describes an approach to ensure this. The equilibrium constant relates to Gibbs free energy and is the start to obtaining other thermodynamic information. The long equilibration times of analytes with the stationary phase observed in this study emphasize the importance of both thermodynamic information and kinetic values for understanding retention. Once equilibrium constants and other parameters are accurately obtained, this information can be used to improve predictions and calculations from numerical models.

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41

Quadri, Mara Gabriela Novy. "Transferts de solutés dans les sols saturés et non saturés : application au pentachlorophénol." Grenoble 1, 1993. http://www.theses.fr/1993GRE10120.

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Les processus de transfert de pesticide dans les sols sont encore mal connus. Avec l'objectif de mieux comprendre les mécanismes impliqués, des essais dans des colonnes remplies avec différents types de sols ont été effectués sous les conditions de saturation et de saturation partielle en eau. Des expériences avec un traceur ont été utilisées pour la caractérisation hydrodynamique du milieu. Les mécanismes d'interaction physicochimiques d'une molécule pesticide modèle, le pentachlorophenol (pcp) avec la matrice solide, sont observés par la comparaison des courbes de restitution du pesticide avec celles du traceur. Les résultats expérimentaux ont montré que les interactions du pcp avec le solide sont dépendants de la succession chronologique des expériences, de la vitesse moyenne d'écoulement, du profil de la teneur en eau dans la colonne, de la concentration en pcp, du ph et de la présence de sel dans la solution injectée. L'isotherme d'adsorption du pcp sur le sable suit le modèle de freundlich, et la restitution partielle est probablement due à une fixation irréversible du pcp ionisé ou non. Un modèle numérique, résolu à l'aide de la méthode des différences finies a été développé. Les descriptions des courbes de restitution des solutes obtenues sur un sable en condition de saturation en eau se sont avérées satisfaisantes. En revanche, le modèle n'a pas permis de décrire complètement les courbes d'élution résultantes de créneaux injectés dans la colonne de sable saturé en semence avec des bactéries, dans le sable partiellement saturé et dans le sol saturé

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42

Benavente, Martha. "Adsorption of Metallic Ions onto Chitosan : Equilibrium and Kinetic Studies." Licentiate thesis, Stockholm : Kemiteknik, Chemical and Engineering and Technology, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4746.

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Alves, Suerda Bezerra. "Estudo teórico e experimental do processo de secagem do abacate (Persea americana Mill)." Universidade Federal da Paraíba, 2014. http://tede.biblioteca.ufpb.br:8080/handle/tede/7576.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
The avocado is a fruit known for its high fat contained in the pulp and like most agricultural products also features a high moisture content in your composition. Drying of the avocado is important since the use of the fruit is performed to obtain a product of greater value, for example, oil serving as a raw material for biodiesel production. This research was developed with the aim to contribute to the theoretical and experimental study of convection drying process of hot air to the avocado in nature, through experimental analysis, mathematical models in the literature and reported an increase of new equations. For the drying process a convective dryer was used, operating in the temperature range of temperature (40, 50, 60 and 70)°C. The geometry of the samples and the flow rate of the drying air were considered constant. For the isotherm Desorption was used a temperature range between was (40, 50, 60, 70, 80 and 90)°C. The validation of the models used in this research was performed by the method of least squares, in possession of the experimental data the kinetic and the desorption isotherms for the avocado in nature. The experimental results of drying kinetics were expressed by models that predict moisture loss through convective mass coefficient and the effective mass diffusivity. The loss of mass on the surface of avocado was expressed by Newton law of cooling, while the inside was expressed by the empirical models represented by Page and Modified. For desorption isotherms the experimental results were demonstrated using models that predict the equilibrium moisture content obtained experimentally in relation to the activity of pre-established water. The desorption isotherm avocado in nature was expressed by the empirical models and Copace amd Sigma-copace. We also developed new mathematical models to represent the kinetic and isotherm avocado in nature.
O abacate é um fruto conhecido pelo seu alto teor lipídico contido em sua polpa e como a maioria dos produtos agrícolas apresenta também um alto teor de umidade em sua composição. A secagem do abacate é importante, uma vez que é realizado o aproveitamento do fruto, para a obtenção de um produto de maior valor agregado como, por exemplo, o óleo que serve de matéria prima para a produção do biodiesel. Esta pesquisa foi desenvolvida com o objetivo de contribuir com o estudo teórico e experimental do processo de secagem por convecção a ar quente, para o abacate in natura, através de análises experimentais, modelos matemáticos reportados na literatura e incremento de novas equações. Para o processo de secagem foi utilizado um secador convectivo, operando na faixa de temperatura (40,50, 60 e 70)ºC. A geometria das amostras e a vazão do ar de secagem foram consideradas constantes. Para as isoterma de desorção foi utilizado uma faixa de temperatura entre (40, 50, 60, 70, 80 e 90)ºC. A validação dos modelos utilizados nesta pesquisa foi realizada através do Método dos Mínimos Quadrados, de posse dos dados experimentais das cinéticas e das isotermas de desorção do abacate in natura. Os resultados experimentais da cinética de secagem foram expressos por modelos que predizem a perda de umidade através do coeficiente convectivo de massa e a difusividade efetiva de massa. A perda de massa na superfície do abacate foi expressa pela Lei de resfriamento de Newton, enquanto que a interna foi expressa pelos modelos empíricos representados por Page e Page Modificado. Para as isotermas de dessorção os resultados experimentais foram demonstrados através de modelos que predizem a umidade de equilíbrio obtida experimentalmente em relação à atividade de água pré-estabelecida. A isoterma de desorção do abacate in natura foi expressa pelos modelos empíricos de Copace e Sigma-copace. Foram ainda desenvolvidos novos modelos matemáticos para representar à cinética e a isoterma do abacate in natura.

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Ha, Wonsook. "Non-isothermal fate and transport of drip-applied fumigants in plastic-mulched soil beds model development and verification /." [Gainesville, Fla.] : University of Florida, 2006. http://purl.fcla.edu/fcla/etd/UFE0012921.

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45

Vorhauer, Nicole [Verfasser], and Evangelos [Gutachter] Tsotsas. "Experiment based development of a non-isothermal pore network model with secondary capillary invasion / Nicole Vorhauer ; Gutachter: Evangelos Tsotsas." Magdeburg : Universitätsbibliothek Otto-von-Guericke-Universität, 2019. http://d-nb.info/1220034878/34.

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46

Ogunleye, Adetoro O. "Bacterial poly-gamma-glutamic acid (γ-PGA) : a promising biosorbent of heavy metals." Thesis, University of Wolverhampton, 2015. http://hdl.handle.net/2436/579925.

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Poly-γ-glutamic acid (γ-PGA) is a biopolymer made up of repeating units of L-glutamic acid, D-glutamic acid or both. γ-PGA is water soluble, non-toxic and biodegradable, and can be used safely in a variety of applications that are increasing rapidly. This study investigated the production of HMW γ-PGA by five Bacillus species (B. licheniformis 1525, B. licheniformis NCTC 6816, B. licheniformis ATCC 9945a, B. licheniformis ATCC 9945a and B. subtilis (natto) ATCC 15245) in GS, C and E media for the removal of heavy metals in wastewaters. The highest γ-PGA yields of 11.69 g/l and 11.59 g/l were produced by Bacillus subtilis (natto) ATCC 15245 in GS medium and medium C respectively. Upon characterization, γ- PGAs with different properties (crystallinity, acid/salt form and molecular weights ranging from 2.56 × 105 Da to 1.65 × 106 Da) were produced. The water soluble, non-toxic, HMW (Mw 1.65 × 106 Da) γ-PGA produced by B. subtilis (natto) ATCC 15245 in medium C was investigated as a sorbent for the removal of heavy metal ions including Cu2+, Zn2+, Ni2+, Cd2+ and Ag+. The results showed that the removal of metals by γ-PGA was more dependent on the concentration of γ-PGA than the solution pH. The highest metal ions removal of 93.50%, 88.13%, 90.21%, 90.56% and 86.34% by HMW γ-PGA were obtained for Cu2+, Zn2+, Ni2+, Cd2+ and Ag+ respectively. The presence of interfering metal ions could hinder the adsorption of individual metal ions by γ-PGA. The affinities of heavy metal ions for γ-PGA followed the order: Cu2+ > Zn2+ > Ni2+ > Cd2+. The effect of molecular weight of γ-PGA on metal removal was also investigated, and it was found that metal ion adsorption capacity of γ-PGA strongly depended on its molecular weight. The maximum amount (93.50%) of Cu2+ sorbed by HMW γ-PGA was higher compared to that (59.48%) sorbed by LMW γ-PGA. Isotherm models showed that the Redlich-Peterson best described the metal adsorption capacity of γ-PGA. It was also found that a multisite adsorption mechanism occurred via the complexation of metal ions with the free α-carboxyl and possibly the amide functional groups in γ-PGA.

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47

Vaghetti, Júlio César Pacheco. "Utilização de biossorventes para remediação de efluentes aquosos contaminados com íons metálicos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/17482.

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Esta tese apresenta a aplicação de biossorventes alternativos obtidos a partir da casca da noz pecã (Carya illinoensis) e da casca do pinhão (Araucaria angustifólia) na remoção de íons metálicos tóxicos presentes em soluções aquosas. O biossorvente de casca de nozes foi aplicado com sucesso na remoção dos íons metálicos: Cu(II), Mn(II), Pb(II), Cr(III), Fe(III) e Zn(II), enquanto que o biossorvente obtido a partir da casca de pinhão apresentou, também, excelente capacidade de adsorção de íons de Cr(VI) em soluções contaminadas pelo mesmo. Os biossorventes casca de nozes PNS (do inglês: pecan nutshell) e casca de pinhão PW (do inglês: Piñon Waste) foram caracterizados química e fisicamente através de: isotermas de adsorção e dessorção de N2, espectroscopia no infravermelho com transformada de Fourier, microscopia de varredura eletrônica, análise elementar, determinação da composição mineral e quantificação de grupos funcionais. A capacidade de adsorção desses biossorventes foi investigada utilizando procedimentos de biossorção em batelada. Os efeitos causados pela modificação de parâmetros experimentais como pH, dosagem de biossorvente e concentração inicial dos íons nos sistemas de adsorção também foram pesquisados. Testou-se a adequação de cinco modelos de cinética de adsorção aos dados experimentais obtidos com o biossorvente PNS, constatou-se que os modelos de ordem-fracionária e o de difusão intrapartícula apresentaram os melhores resultados. Já para adsorções de Cr(VI) em PW o melhor modelo cinético foi o de quimiossorção de Elovich, apresentando taxas de biossorção de 284,9, 396,9 e 461,5 mg g-¹ h-¹ para os níveis de concentração inicial de Cr(VI) de 500,0, 700,0 e 1000,0 mg l-¹ respectivamente. O estudo do equilíbrio de adsorção envolveu a aplicação dos modelos de isotermas de: Langmuir, Freundlich, Redlich-Peterson e Sips aos dados experimentais no intuito de verificar o modelo mais apropriado para descrever os sistemas de adsorção quando em equilíbrio. Avaliou-se, utilizando a função estatística de erro, que o modelo de Sips foi o que mais se adequou aos dados experimentais obtidos nos diversos sistemas pesquisados (biossorvente - ion metálico). A capacidade máxima de adsorção para íons de Cr(III), Fe(III), Zn(II), Cu(II), Mn(II) e Pb(II) em PNS foi de 93,0, 76,6, 108,0, 85,9, 98,0 e 195,9 mg g-¹, respectivamente, enquanto que a de Cr(VI) em PW foi de 240,0 mg g-¹.
This thesis reports the possibility of applying the alternative biosorbent pecan nutshell (PNS- Carya illinoensis) used to remove the followed metallic ions: Cu(II), Mn(II), Pb(II), Cr(III), Fe(III), Zn(II) from aqueous solutions. This thesis also shows the application of Brazilian-pine fruit coat, named piñon wastes (PW; Araucaria angustifolia) as biosorbent to remove Cr(VI) from aqueous solutions. The PNS and PW biosorbents were characterized by N2 adsorption-desorption isotherms, FTIR spectroscopy, scanning electron microscopy, elemental analysis, mineral composition determination, and functional groups detection. The biosorbents ability to remove the metallic ions was investigated by using batch biosorption procedure. The effects of changing experimental parameters such as, pH, biosorbent dosage and initial ion concentration on the biosorbents adsorption capacities were studied. Five kinetic models were tested, being the adsorption kinetics better fitted to fractionary-order kinetic model. Besides that, the kinetic data were also fitted to intra-particle diffusion model, presenting three linear regions, indicating that the kinetics of adsorption should follow multiple sorption rates. The equilibrium data were fitted to Langmuir, Freundlich, Sips and Redlich-Peterson isotherm models. Taking into account a statistical error function, most of PNS biosorption equilibrium data were best fitted to Sips isotherm model. The maximum biosorption capacity of PNS were 93.0, 76.6, 108.0, 85.9, 98.0 and 195.9 mg g-¹ for Cr(III), Fe(III), Zn(II), Cu(II), Mn(II) and Pb(II), respectively. The adsorption kinetics followed the Elovich chemisorption kinetic model, obtaining the following the initial adsorption rate, 284.9, 396.9 and 461.5 mg g-¹ h-¹ using a 500.0, 700.0 and 1000.0 mg L-¹ initial concentration of Cr(VI), respectively. The maximum adsorption capacity of PW was 240.0 mg g-¹ for Cr(VI), using Sips isotherm model. This high adsorption capacity of PW places this biosorbent as one of the best adsorbents for removal of Cr(VI) from aqueous effluents.

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Bagnoli, Annalisa. "Diffuse interface models for tumour growth within a non-isothermal Cahn-Hilliard theory for phase separation: thermodynamics, chemotaxis and stability." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14120/.

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In this thesis we provide a scheme for phase separation by accounting for diffusion, dynamic equations and consistency with thermodynamics. The constituents are two compressible fluids and, for the non-simple character of the mixture, an extra energy flux is allowed to occur. Since also thermal effects are included, the result is a whole set of evolution equations for the concentration, the velocity and the temperature which describes a non-isothermal Navier-Stokes-Cahn-Hilliard model for phase separation in a binary mixture with extra fluxes and within the Fourier heat theory. Alternative heat theories may be proposed for this Navier-Stokes-Cahn-Hilliard theory. Meanwhile the mixing problem is described graphically. Moreover the model may be generalized including a source term, and this doesn't affect the thermodynamic scheme. Then we describe and then compare two mathematical models for chemotactic processes: the pioneeristic Keller-Segel model and the hydrodynamic model by Chavanis and Sire. The first one is able to describe clusters or peaks, the second one involves inertial effects together with a friction force and leads to network patterns or filaments that are in good agreement with the experimental results. We analyze the linear stability of an infinite, stationary and homogeneous distribution of cells for determining the critical thresholds above which chemotactic collapse is allowed and cellular aggregation is reproduced. Then we discuss the differences between the two models, moreover we show the analogy between the instability criterion for biological populations and the Jeans instability criterion in an astrophysical setting. Finally we propose a different approach for the derivation of new diffuse interface models for tumour growth (with chemotaxis and active transport) based on the Cahn-Hilliard theory, combined with the (stationary) Darcy momentum equation.

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Paul, Uchenna Prince. "Microkinetic Model of Fischer-Tropsch Synthesis on Iron Catalysts." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2535.pdf.

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Strey, Leonardo. "Biossorção de íons metálicos em águas utilizando casca de pinus como material adsorvente alternativo." Universidade Estadual do Oeste do Paraná, 2013. http://tede.unioeste.br:8080/tede/handle/tede/1253.

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This work proposes the use of the bark of Pinus elliottii, a residue of wood processing, as biosorbent in the removal of metal ions Cd2+, Pb2+ and Cr3+solutions fortified, as an alternative to conventional treatment methods, such as precipitation, ion exchange, electrochemical treatment, flocculation and filtration. The biosorbent was characterized by scanning electron microscopy (SEM), infrared spectroscopy (FT-IR) and point of zero charge (pHPCZ). Adsorption tests were performed aiming to determine the optimal conditions of pH, mass of adsorbent and contact time for the adsorption process. The adsorption kinetics was evaluated by pseudofirst and pseudosecond order models, Elovich and intraparticle diffusion. Adsorption isotherms for each metal were constructed, which were linearized according to mathematical models of Langmuir, Freundlich and Dubinin-Radusckevich. To compare this biosorbent with a commercial adsorbent, comparative studies with activated charcoal were performed . Furthermore, we evaluated the ability of desorption of materials and the influence of temperature on adsorption of metals studied by pine bark. The characterization of the biosorbent by SEM showed a rough and heterogeneous surface, important adsorption characteristics. From the FT-IR was identified compounds such as lignin, cellulose and hemicellulose, which favor the adsorption process. The pHPZC obtained was 3.5. The mass tests showed that 8 g L-1 biosorbent are sufficient for efficient removal of metal ions in solution. From the tests of pH, optimum conditions were obtained: 7.0 for Cd and 5.0 to Pb and Cr. The equilibrium time for adsorptive process were 40, 20 and 80 min for Cd, Pb and Cr, respectively. With the application of kinetic models is possible to suggest that the main limiting step for adsorption of these metal ions may be the chemisorption. The mathematical models that best fitted for the adsorption pine bark were Dubinin-Radushkevich for Cd, Freundlich for Pb, and Langmuir and Freundlich for Cr. The increase in temperature increased removal efficiency and, furthermore, with the thermodynamic parameters, it was found that the adsorption process is controlled by chemisorption. Desorption values were low, indicating a strong interaction of the metal with the surface of the adsorbent. In comparative studies with activated coal its possible to concluded that, despite the bark of Pinus elliottii present an adsorption efficiency less than this, the same satisfactory results of adsorption and removal of metal ions present in solutions fortified. Thus, it is concluded that the use of the bark of Pinus elliottii as biosorbents showed a promising alternative for the decontamination of contaminated water bodies by metal ions Cd, Pb and Cr
O presente trabalho propõe a utilização da casca de Pinus elliottii, um resíduo do beneficiamento da madeira, como biossorvente na remoção dos íons metálicos Cd2+, Pb2+ e Cr3+ de meio aquoso, como alternativa aos métodos convencionais de tratamento, como a precipitação, troca iônica, tratamento eletroquímico, floculação e filtração. O biossorvente foi caracterizado por meio de microscopia eletrônica de varredura (MEV), espectroscopia na região do infravermelho (FT-IR) e ponto de carga zero (pHPCZ). Após a caracterização foram realizados testes de adsorção objetivando determinar as condições ideais de pH, massa de adsorvente e tempo de contato para o processo de adsorção. A cinética de adsorção foi avaliada pelos modelos de pseudoprimeira ordem, pseudossegunda ordem, Elovich e difusão intrapartícula. Foram construídas as isotermas de adsorção para cada metal, as quais foram linearizadas conforme os modelos matemáticos de Langmuir, Freundlich e Dubinin-Radusckevich. Visando comparar este biossorvente com um adsorvente comercial, foram realizados estudos comparativos com o carvão ativado. Além disso, foram avaliados a capacidade de dessorção dos materiais e a influência da temperatura no processo de adsorção dos metais em estudo pela casca de pinus. A caracterização do biossorvente por meio da técnica de MEV mostrou uma superfície irregular e heterogênea, importantes características de adsorção. A partir da FT-IR foi possível identificar grupos funcionais comuns a estrutura da lignina, celulose e hemicelulose, os quais favorecem o processo de adsorção. O pHPCZ obtido foi de 3,5. Os testes de massa demonstraram que 8 g L-1 do biossorvente são suficientes para uma remoção eficiente dos íons metálicos em solução. A partir dos testes de pH, as condições ideais obtidas foram: 7,0 para Cd e, 5,0 para Pb e Cr. Os tempos de equilíbrio para o processo adsortivo foram 40, 20 e 80 min, para Cd, Pb e Cr, respectivamente. Com a aplicação dos modelos cinéticos sugere-se que a etapa limitante para a adsorção destes íons metálicos pode ser a quimiossorção. Os modelos matemáticos que melhor se ajustaram para a adsorção em casca de pinus foram Dubinin-Radushkevich para o Cd, Freundlich para Pb e, Langmuir e Freundlich para o Cr. O incremento na temperatura aumentou eficiência de remoção e, além disso, com os parâmetros termodinâmicos, concluiu-se que o processo de adsorção é controlado pela quimissorção. Os valores de dessorção foram baixos, indicando uma forte interação dos metais com a superfície do adsorvente. Com os estudos comparativos com o carvão ativado foi possível concluir que apesar da casca de Pinus elliottii apresentar uma eficiência de adsorção menor que este, a mesma apresentou resultados satisfatórios de adsorção e remoção dos íons metálicos presentes nas soluções fortificadas. Assim, conclui-se que a utilização da casca de Pinus elliottii como biossorvente mostrou-se uma alternativa promissora para descontaminação de corpos hídricos contaminados pelos íons metálicos Cd, Pb e Cr

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