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1
Veal, Andrew Richard. "Models of polymer adsorption and collapse." Thesis, University of Oxford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277107.
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Onugha, Leonard C. "Kinetic models for protein adsorption on porous cylindrical particles." Thesis, Swansea University, 2002. https://cronfa.swan.ac.uk/Record/cronfa42788.
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Most chromatographic purification techniques for macromolecuies (biopolymers) operate on the principles of adsorption. The rate of the adsorption process depends on mass transfer kinetics. Previous models of the adsorption kinetics have assumed that the adsorbent/packing particles used are spherical. Adsorbents which are fibrous or consist of rod-like particles offer potential advantages over the spherical particles. Whatman UK Ltd. market a semi-rigid cellulosic range of chromatographic adsorbents for macromolecule separation (Express-Ion) which are of this type, i.e. may be likened in shape to cylinders. The major aim of this study is to develop detailed kinetic models for the pore diffusion and mass transfer processes governing the adsorption kinetics of proteins that will predict the concentration-time profiles for the adsorption in both stirred tank and packed column modes of operation using semi-rigid cylindrical adsorbents. 1 he models have been developed to allow for particle size distribution within adsorbent samples, and for the delay and mixing that occurs in the flow line of the equipment. The stirred cell model constructed has been validated by fitting theoretical data to experimental curves obtained for the adsorption of bovine serum albumin on the anion exchanger Express-Ion D. This system was characterised by determining adsorption isotherms and the physical parameters of the adsorbent. The effects of varying the protein concentration, effective pore diffusivity, liquid film mass transfer coefficient, particle dispersity, number of particle size groups, stirrer speed, and the equilibrium isotherm parameters on the adsorption profiles has been studied. A packed bed variant model has also been constructed and used to predict the effect of process parameters on the breakthrough curve in a packed bed (chromatographic) mode, and to study the effects of particle geometry on the adsorption process.
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Seitsonen, Ari Paavo. "Theoretical investigations into adsorption and co-adsorption on transition metal surfaces as models to heterogeneous catalysis." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=963831291.
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Johnson, William H. "Sorption models for U, Cs, and Cd on upper Atlantic Coastal Plain soils." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/16609.
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Huggahalli, Madhusudhan. "Steam regeneration of activated carbon beds : mechanisms and models /." Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Bhattacharya, Supriyo. "Molecular Models for Templated Mesoporous materials: Mimetic Simulation and Gas Adsorption." NCSU, 2006. http://www.lib.ncsu.edu/theses/available/etd-01062006-163437/.
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The complex structures of the Templated Mesoporous Materials (TMMs) are difficult to capture using experiments. On the other hand, detailed structural information is required in order to study the confinement effects and predict material properties. We therefore present a methodology to prepare realistic molecular models of the TMMs using molecular simulations. Mimetic simulations are used to simulate the synthesis of the TMMs resulting in mesoscale models of the materials. Using this technique, we have developed models for SBA-15 and the Mesostructured Cellular Foams (MCF). The mimetic simulations also allow us to study the phase diagrams of the surfactants involved in the synthesis. We have investigated the ternary phase diagrams (surfactant-oil-water and surfactant-silica-water) of model triblock surfactants and have highlighted the effects of oil on the ordered structures. The simulation results for the effect of oil are in partial agreement with the experiments. Next, we devise a technique to convert the mesoscale TMM models into atomistic ones. The method has been demonstrated by preparing atomistic models for SBA-15. The physical properties of the models (pore size distribution, surface area, TEM and AFM images) are compared to the experimental ones. The porosities and the surface areas of the models are in quantitative agreement with those of the experimental SBA-15, whereas the pore size distribution and TEM results agree qualitatively with the experiments. We also present new methods for characterizing model structures including a fast technique for computing pore size distributions. The results from our new technique show speed increases of several orders of magnitude compared to the existing method. Finally we simulate the adsorption of Argon inside the model SBA-15 using Grand canonical Monte Carlo simulations. The adsorption isotherm from the model is in semi-quantitative agreement with that of an experimental SBA-15. The adsorption behavior of several different pore models are investigated, which provides new light on the roles of surface roughness and micropores in determining adsorption properties. We conclude by saying that the pore models developed in this work may be used in studying phase transitions, adsorption, diffusion and reactions inside nanopores, and in preparing new mesoporous material models such as the CMK carbons.
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Bell, Jon Grahame. "Adsorption characteristics of models for dioxins on modified nanoporous activated carbons." Thesis, University of Newcastle Upon Tyne, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516433.
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Liu, Xiu. "Fundamental Study of Gas Adsorption in Porous Materials using More Realistic Models." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/81777.
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This thesis presented a fundamental study on the gas adsorption in carbonaceous materials with more realistic models, including wedge pore and connected deformable pore. Monte Carlo simulation was used to evaluate the adsorbate potentials and investigate the mechanisms of various adsorption phenomena. A special effort was spent on developing a new mercury potential model to improve the understanding of mercury interaction with carbonaceous materials, which has important practical application in industry.
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Dye, Colin. "Phosphate adsorption by ferric oxide gel, the effect of organic anions and the usefulness of some models for interpreting the adsorption data." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304850.
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Todd, Richard Shannon. "A theoretical and experimental study of a rapid pressure swing adsorption system for air separation." Monash University, Dept. of Chemical Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/5533.
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Brown, Pauline Anne. "The application of peat and lignite to the removal of heavy metals from industrial wastewater." Thesis, Queen's University Belfast, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360482.
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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.<br>Ph. D.
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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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Hasan, Nazmul. "Adequacy of surface diffusion models to simulate nonequilibrium mass transfer in soils." Online access for everyone, 2008. http://www.dissertations.wsu.edu/Thesis/Summer2008/n_hasan_063008.pdf.
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Beh, Christopher Chun Keong. "Vacuum swing adsorption process for oxygen enrichment : a study into the dynamics, modelling and control." Monash University, Dept. of Chemical Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/9533.
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Lin, Tzu-Jen. "Force Field Parameters and Atomistic Surface Models forHydroxyapatite and Analysis of Biomolecular Adsorption at Aqueous Interfaces." University of Akron / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1365511604.
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Silvino, Pedro Felipe Gadelha. "Virtual models applied to activated carbon characterization." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13357.
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AgÃncia Nacional do PetrÃleo<br>Activated carbons are amorphous materials represented by a pore size distribution (PSD) which usually reproduce the experimental isotherm of N2 at 77 K. Presently, we obtain this distribution using the activated carbon slit-pore model and isotherms calculated by molecular simulation. In this study, we have evaluated the extent to which the use of more realistic activated carbon models influences on the characterization, as well as the possibility of representing the activated carbon by a minimum three-pore PSD. Adsorption isotherms were calculated using the Grand Canonical ensemble within the Monte Carlo method, and compared with experimental isotherms of commercial activated carbons. The deconvolution method with non negative least squares was used to determine the PSDs. We observed that the models containing heterogeneity factors were more accurate than the simplified models, and that activated carbons could be well represented by a minimum three-pore distribution without significant loss of precision. Furthermore, we demonstrated that the minimum PSD could be applied to formulate virtual porous carbon models that are useful in the heterogeneity study. Finally, we propose the use of the minimum PSD to replace the classical calculations of average pore size.<br>Carbonos ativados sÃo materiais amorfos representados por uma distribuiÃÃo de tamanho de poros (PSD) que usualmente reproduz a isoterma experimental de N2 a 77 K. Presentemente esta distribuiÃÃo à obtida com o uso do modelo de carbono ativado de placas paralelas de grafeno e isotermas calculadas por simulaÃÃo molecular. Neste estudo avaliou-se a influÃncia do uso de modelos de poros de carbono ativado mais realistas sobre a caracterizaÃÃo, bem como a possibilidade de representar o carbono ativado por uma PSD mÃnima constituÃda de apenas trÃs poros. Isotermas de adsorÃÃo foram calculadas utilizando-se o algoritmo de Monte Carlo no ensemble grande canÃnico e comparadas com as isotermas experimentais de carbonos ativados comerciais. O mÃtodo de deconvoluÃÃo com mÃnimos quadrados nÃo negativos foi utilizado para determinaÃÃo das PSDs. Observou-se que modelos contendo fatores de heterogeneidade mostraram-se mais precisos que os modelos simplificados. Notou-se ainda que efetivamente o carbono ativado pode ser representado por uma PSD mÃnima de trÃs poros sem perda significativa de precisÃo. AlÃm disso, demonstrou-se que a distribuiÃÃo mÃnima pode ser usada para elaborar modelos virtuais de carbono que sÃo Ãteis no estudo de heterogeneidades. Finalmente propomos o uso da PSD mÃnima em substituiÃÃo ao cÃlculo clÃssico de tamanho mÃdio de poros.
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Esfandiari, Baiat Mansour, of Western Sydney Hawkesbury University, of Science Technology and Agriculture Faculty, and School of Agriculture and Rural Development. "Evaluation of furrow irrigation models for south-east Australia." THESIS_FSTA_ARD_EsfandiariBaiat_M.xml, 1997. http://handle.uws.edu.au:8081/1959.7/739.
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The overall objective of this study was to evaluate the performance of selected furrow irrigation models for field conditions in south-east Australia. The other important aspects which were examined during this study include: developing a methodology for estimating of infiltrating characteristics, assessing the applicability of the Manning and other similar equations for flows in furrow irrigation, investigating the variation of shape factor during irrigation developing methodology for estimation of recession time and exploring the sensitivity of the models to the input parameters. Field experiments were conducted at Walla Park in northern N.S.W. and on two selected paddocks at the University Farm, Richmond, in western Sydney,Australia, over a period of three years. The validity of the assumption that the shape factor of advancing water front during furrow irrigation varies between 0.7 and 0.8 was investigated using field data collected from irrigation events monitored in the study. It was found that the average values of the shape factor varied from 0.96 to 1.80 at Walla Park site, from 0.56 to 0.80 at Field Services unit paddock site and from 0.78 to 0.84 at Horticulture Farm paddock site. The value of shape factor was affected by uniformity of furrow cross section along the length, the value and uniformity of furrow slope, furrow length and infiltration characteristics of soil. This means it is difficult to recommend a typical value for the shape factor for a given field situation.The performance of the models for prediction of advance and recession characteristics and runoff were evaluated using different indices of performance. In general, it was found that the Walker-HD and ZI model was the most satisfactory for the field conditions encountered in this study. This finding can provide a basis for initiating work on developing design criteria and management strategies for furrow irrigation in south-east Australia.<br>Doctor of Philosophy (PhD)
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Chadik, Paul Arthur. "Modeling trihalomethane formation in drinking water after alum coagulation or activated carbon adsorption." Diss., The University of Arizona, 1985. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1985_293_sip1_w.pdf&type=application/pdf.
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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<br>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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Freeman, Diane Elizabeth. "Effect of DOPA on the adsorption of colour and Maillard browning kinetics in sugar beet diffusion models." Thesis, University of Leeds, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396682.
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Maharaj, Bikash Chandra. "Based mathematical models for assessing the effect of trace elements dynamics on solid waste anaerobic digestion." Thesis, Paris Est, 2019. http://www.theses.fr/2019PESC2039.
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La digestion anaérobie (MA) est l’un des processus métaboliques les plus riches en oligoéléments (TE) en biologie. En effet, les TE sont des composants structuraux importants de diverses enzymes dans le processus AD. Le rôle et le devenir des TE (Fe, Ni et Co) dans l’AD est mal compris en raison de leur biogéochimie complexe. La faible limite de détection des instruments d’analyse et le temps et la nature exigeante des procédures expérimentales sont des obstacles majeurs à la quantification des TE dans la MA. Dans cette thèse, trois modèles mathématiques distincts basés sur l’ADM1 ont été développés pour simuler la dynamique des TE et le profil de spéciation dans un réacteur AD. En particulier, un modèle de précipitation/dissolution TE, un modèle de complexation TE et un modèle d’adsorption TE ont été développés progressivement pour prédire l’effet, le rôle et le devenir (...)<br>Anaerobic digestion (AD) is one of the most trace element (TE) rich metabolic processes in biology. Indeed, TEs are important structural components of various enzymes in the AD process. The role and fate of TEs (Fe, Ni and Co) in AD is poorly understood due to their complex biogeochemistry. The low detection limit of analytical instruments and the time consuming and challenging nature of the experimental procedures are major obstacles to the quantification of TEs in AD. In this thesis, three separate mathematical models based ADM1 have been developed to simulate the TEs dynamics and speciation pattern in an AD reactor. In particular, a TE precipitation/dissolution model, a TE complexation model and a TE adsorption model have been progressively developed to predict the effect, role and fate of TEs in an AD batch system. In all the models the extent of microbial activity in the AD process is a function of the free TE concentration in the liquid phase, which is in equilibrium with the physicochemistry of the AD reactor. The precipitation/dissolution model considers the interactions of TEs with inorganic carbon (e.g. HCO3- and CO32-), phosphorous (e.g. PO43-, HPO42-, H2PO4-) and sulfur (e.g. HS- and S2-) components. New chemical equilibrium acid-base and precipitation reactions have been implemented to study the interactions of Fe, Ni, Co with carbonate, phosphate and sulfide components. The effects of deficiency, stimulation, inhibition and toxicity of TEs on microbial activity have been modelled based on a hormesis type TE dose-response inhibition function. The microbial uptake of TE and the TE inhibition on special microbial activities have been defined as well. Release of TEs as a disintegration product has been also considered to account for the TE content of the organic substrate. Model scenarios have been simulated to analyze the dynamics of TEs, starvation of TEs and the effect of initial sulfur-phosphorus ratio. In the complexation model, the interactions of TEs with organic chelators have been predicted. TE complexation reactions with VFAs and EDTA have been incorporated in the extended ADM1 model in addition to TE precipitation/dissolution processes. New acid-base chemical equilibrium reactions have been incorporated to model the dynamics of EDTA species. Complexation process rates have been defined as well. The model is able to quantify the effect of EDTA/VFA -TE complexation on methane production. Further, effect of initial Ca and Mg concentration on TE complexation has been predicted in a separate modeling scenario. Finally, a general framework able to take into account the precipitation/dissolution and complexation reactions, as well as the interaction of TEs with various surfaces available in the AD system has been developed. The model tracks the TEs dynamics in a batch anaerobic digester and as an extension of the previous contributions, incorporates the adsorption reactions of TEs with biomass, inert and precipitate (FeS). The concepts of free and occupied binding sites, and binding site density for the various surfaces have been incorporated into the model. Simulation scenarios were able to predict the effect of various organic matter concentrations, initial TE concentrations, initial Ca-Mg concentrations, initial EDTA concentrations and change in TE binding site density for biomass, inert and precipitate on cumulative methane production and TE speciation
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Ferreiro, Rangel Carlos Augusto. "Molecular simulation studies in periodic mesoporous silicas SBA-2 and STAC-1 : model development and adsorption applications." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5272.
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Adsorption is a low-energy separation process especially advantageous when the components to be separated are similar in nature or have a low molar concentration. The choice of the adsorbent is the key factor for a successful separation, and among them periodic mesoporous silicas (PMS) are of importance because of their pore sizes, shapes and connectivity. Furthermore, they can be modified by post-synthesis functionalisation, which provides a tool for tailoring them to specific applications. SBA-2 and STAC-1 are two types of PMS characterised by a three-dimensional pore system of spherical cages interconnected by a network of channels whose formation process was until now obscure. In this work the kinetic Monte Carlo (kMC) technique has been extended to simulate the synthesis of these complex materials, presenting evidence that the interconnecting network originates from spherical micelles touching during their close-packing aggregation in the synthesis. Moreover, for the first time atomistic models for these materials were obtained with realistic pore-surface roughness and details of the possible location of its interaction sites. Grand Canonical Monte Carlo (GCMC) simulations of nitrogen, methane and ethane adsorption in the materials pore models show excellent agreement with experimental results. In addition, their potential as design tools is explored by introducing surface groups for enhancing CO2 capture; and finally, application examples are presented for carbon dioxide capture from flue gases and for natural gas purification, as well as in the separation of n-butane / iso-butane isomers.
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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.<br>Ph. D.
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Tran, Van Nam. "Adsorption statique de PCB et de DDT sur charbons actifs en milieux aqueux." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10301.
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L’adsorption solide-liquide des PCB et des DDT constitue un moyen efficace pour leur récupération des eaux polluées à condition d’avoir une meilleure connaissance du mécanisme impliqué. Les cinétiques d’adsorption statique ont été principalement réalisées à 25 °C avec le2-PCB, un mélange de tétra-, penta- et hexa-CB et le 4,4’-DDT sur 3 charbons actifs (CA) en poudre différents par le précurseur (houille, bois) et le mode d’activation (H2O, H3PO4) dans l’eau, en présence ou non d’éthanol. Les résultats marquants ont été les suivants : L’adsorption du polluant sur le CA est d’autant plus favorisée que sa solubilité dans la phase liquide est plus faible. Ainsi, l’adsorption du polluant hydrophobe est très augmentée dans l’eau pure. L’adsorption des polluants favorisée par la microporosité développée est essentiellement un phénomène de surface où interviennent les forces de Van der Waals. Une bonne adéquation entre la taille des molécules et la largeur moyenne des pores en forme de fentes montre un confinement maximum des molécules dans la microporosité. L’interaction π−π entre adsorbat et adsorbant, favorisée par le nombre de Cl n’est pas à exclure. Enfin, nous avons montré par la cinétique dans les conditions initiales que l’adsorption y est limitée par le transfert de masse externe. Les modélisations par diffusion superficielle homogène (HSDM), conduisant aux coefficients de diffusion superficielle interne, ont montré que la cinétiqued’adsorption est presque complètement gouvernée par la diffusion intraparticulaire<br>The solid-liquid adsorption of PCBs and DDT is an effective process for the recuperation of wastewaters but a better understanding of the involved mechanism is required. In this study, the static adsorption kinetics were mainly carried out at 25 ° C for 2-PCB, a mixture of tetra-, penta-and hexa-CB, and 4,4 '-DDT onto three different powdered activated carbons (AC) of the precursor (coal, wood) and the activation mode (H2O, H3PO4) in water, with or without ethanol. The prominent results were as follows: The adsorption of the pollutant on the AC is favored if its solubility in the liquid phase is lower. As a result, the adsorption of the hydrophobic pollutant is significantly increased in pure water. Moreover, the adsorption of pollutants favored by the developed microporosity is a surface phenomenon which involved the Van der Waals forces. A good fit between the size of molecules and the average width of the slit-shape pores gave a maximum confinement of molecules in the micropores. The π−π interaction between adsorbate and adsorbent, favored by the number of Cl, is not excluded. Finally, by studying the kinetics of the initial conditions, we found that the adsorption is limited by the external mass transfer. The internal surface diffusion coefficients estimated from applying the homogeneous surface diffusion models (HSDM) showed that the adsorption kinetics are almost completely governed by the intra-particle diffusion
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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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Previous issue date: 2013-08-01<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>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<br>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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Odem, Wilbert Irwin. "COMPETITIVE ADSORPTION OF VOLATILE ORGANIC COMPOUNDS ONTO NATURAL AND SYNTHETIC ADSORBENTS (TRICHLOROETHYLENE, 1,4-DICHLOROBENZENE, TETRACHLOROETHYLENE, CARBON TETRACHLORIDE, PREDICTIVE MODELS)." Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275458.
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Mukherjee, Moumita. "Instrumented permeable blankets for estimating subsurface hydraulic conductivity and confirming numerical models used for subsurface liquid injection." Diss., Connect to online resource - MSU authorized users, 2008.
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Msaky, John Joseph. "Adsorption et desorption du cuivre et du zinc dans les sols." Paris 6, 1987. http://www.theses.fr/1987PA066094.
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Conditions experimentales: effet du rapport masse de terre-volume de solution sur la charge electrique de surface solide. Quand il augmente les quantites adsorbees diminuent. La nature et la concentration des ligands mineraux et organiques ainsi que la forme ionique du milieu influencent l'adsorption du metal. L'adsorption du cu et du zn est differente selon le type du sol, le ph du systeme et la nature du cation competiteur. L'etude de la desorption montre que les metaux, une fois adsorbes, ne sont pas facilement desorbes
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Dombek, Priscilla Emily 1961. "IMPROVING THE CONVERSION OF THE SULFUR DIOXIDE - LIME REACTION BY USING ADDITIVES." Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/291523.
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Branko, Kordić. "Ispitivanje uticaja odabranih amida na adsorpciju nitro derivata fenola iz vodene sredine na aktivnom uglju." Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2019. https://www.cris.uns.ac.rs/record.jsf?recordId=110733&source=NDLTD&language=en.
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U radu je ispitan uticaj amida kao modela AOM-a (Algalne organske materije) na adsorpciju nitrofenola iz vodene sredine na aktivnom uglju. Istraţivanje se sastojalo iz tri faze: ispitivanje uticaja karateristika amida na adsorpciju nitrofenola, ispitivanje uticaja granulacije na adsorpciju nitrofenola u prisustvu amida i ispitvanje karakterisitka samih nitrofenola na adsorpciju u prisustvu amida. Pre ispitivanja adsorpcije u dvokomponentnim sistemima ispitana je adsorpcija jednokomponentnih sistema 4-nitrofenola, 2,4-dinitrofenola i 2,4,6-trinitrofenola, kao i amida Nmetilbenzamid, nikotinamida i N-benzilbenzamida na komercijalnim aktivnim ugljevima NORIT SA2 i dve granulacije aktivnog uglja DARCO. Aktivni ugljevi su ispitani metodom FTIR spektroskopije, SEM analizom, analizom površine adsorpcijom azota na niskoj temperaturi i određivanjem taĉke nultog naelektrisanja. Urađena je geometrijska optimizacija modela molekula ispitivanih nitrofenola i amida i izraĉunati su molekulski parametri. Uticaj amida kao modela AOM-a je ispitan korišćenjem razliĉitih ravnotežnih i difuzionih adsorpcionih modela. Kao kriterijum za određivanje najsporije adsorpcione faze korišćen je Biotov broj.Adsorpcioni parametri dobijeni u eksperimentima sa dvokomponentnim sistemima su upoređivani sa parametrima dobijenim za adsorpciju samih nitrofenola.<br>In this research influence of selected amides, as a model of AOM (Algal organic matter), on adsorption of nitrophenols from water on activated carbon has beeninvestigated. Research is divided in three phases: investigation of influence of amide molecule characteristics on the adsorption of nitrophenols, investigation of granulation influence on nitrophenol adsorption in the presence of amide and investigation of nitrophenol characteristics that can influence adsorption in the presence of amides. Adsorption of nitrophenols and amides in single- component systems has also been carried out. Adsorption kinetics of 4-nitrophenol, 2,4-dinitrophenol, 2,4,6-trinitrophenol, N-methylbenzamide,nicotinamide and N-benzylbenzamide has also been investigated. Commercial activated carbons NORIT SA2 and two granulations of DARCO were used. Activated carbons were characterized using FTIR spectroscopy, SEM analysis, internal surface analysis using nitrogen adsorption on low temperature and determination of point of zero charge. Geometry optimization of nitrophenol and amide molecules has been carried out and different molecular parameters have been calculated. Influence of amides as AOM model has been investigated by using diffusion and equilibrium models. Biot number has been obtained in order to establish the limiting step in adsorption process. Adsorption parameters obtained in two-component adsorption systems were compared to parameters obtained for adsorption of nitrophenols alone.
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Kangas, J. (Jani). "Separation process modelling:highlighting the predictive capabilities of the models and the robustness of the solving strategies." Doctoral thesis, Oulun yliopisto, 2014. http://urn.fi/urn:isbn:9789526203768.
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Abstract The aim of this work was to formulate separation process models with both predictive capabilities and robust solution strategies. Although all separation process models should have predictive capabilities, the current literature still has multiple applications in which predictive models having the combination of a clear phenomenon base and robust solving strategy are not available. The separation process models investigated in this work were liquid-liquid phase separation and membrane separation models. The robust solving of a liquid-liquid phase separation model typically demands the solution of a phase stability analysis problem. In addition, predicting the liquid-liquid phase compositions reliably depends on robust phase stability analysis. A phase stability analysis problem has multiple feasible solutions, all of which have to be sought to ensure both the robust solving of the model and predictive process model. Finding all the solutions with a local solving method is difficult and generally inexact. Therefore, the modified bounded homotopy methods, a global solving method, were further developed to solve the problem robustly. Robust solving demanded the application of both variables and homotopy parameter bounding features and the usage of the trivial solution in the solving strategy. This was shown in multiple liquid-liquid equilibrium cases. In the context of membrane separation models, predictive capabilities are achieved with the application of a Maxwell-Stefan based model. With the Maxwell-Stefan approach, multicomponent separation can be predicted based on pure component permeation data alone. On the other hand, the solving of the model demands a robust solving strategy with application-dependent knowledge. These issues were illustrated in the separation of a H2/CO2 mixture with a high-silica MFI zeolite membrane at high pressure and low temperature. Similarly, the prediction of mixture adsorption based on pure component adsorption data alone was successfully demonstrated. In the context of membrane separation models, predictive capabilities are achieved with the application of a Maxwell-Stefan based model. With the Maxwell-Stefan approach, multicomponent separation can be predicted based on pure component permeation data alone. On the other hand, the solving of the model demands a robust solving strategy with application-dependent knowledge. These issues were illustrated in the separation of a H2/CO2 mixture with a high-silica MFI zeolite membrane at high pressure and low temperature. Similarly, the prediction of mixture adsorption based on pure component adsorption data alone was successfully demonstrated<br>Tiivistelmä Työn tavoitteena oli muotoilla prosessin käyttäytymisen ennustamiseen kykeneviä erotusprosessimalleja ja niiden ratkaisuun käytettäviä luotettavia strategioita. Vaikka kaikkien erotusprosessimallien tulisi olla ennustavia, on tällä hetkellä useita kohteita, joissa prosessin käyttäytymistä ei voida ennustaa siten, että käytettävissä olisi sekä ilmiöpohjainen malli että ratkaisuun soveltuva luotettava strategia. Tässä työssä erotusprosessimalleista kohteina tarkasteltiin neste-neste-erotuksen ja membraanierotuksen kuvaukseen käytettäviä malleja. Neste-neste-erotusmallien luotettava ratkaisu vaatii yleensä faasistabiilisuusongelman ratkaisua. Lisäksi faasien koostumusten luotettava ennustaminen pohjautuu faasistabiilisuusanalyysiin. Faasistabiilisuusongelmalla on useita mahdollisia ratkaisuja, jotka kaikki tulee löytää, jotta voitaisiin varmistaa luotettava mallin ratkaisu sekä prosessimallin ennustuskyvyn säilyminen. Kaikkien ratkaisujen löytäminen on sekä vaikeaa että epätarkkaa paikallisesti konvergoituvilla ratkaisumenetelmillä. Tämän vuoksi globaaleihin ratkaisumenetelmiin kuuluvia modifioituja rajoitettuja homotopiamenetelmiä kehitettiin edelleen, jotta faasistabiilisuusongelma saataisiin ratkaistua luotettavasti. Ratkaisun luotettavuus vaati sekä muuttujien että homotopiaparametrin rajoittamista ja ongelman triviaalin ratkaisun käyttöä ratkaisustrategiassa. Tämä käyttäytyminen todennettiin useissa neste-nestetasa-painoa kuvaavissa esimerkeissä. Membraanierotusta tarkasteltaessa ennustava malli voidaan muotoilla käyttämällä Maxwell-Stefan pohjaista mallia. Maxwell-Stefan lähestymistavalla voidaan ennustaa monikomponenttiseosten erotusta perustuen puhtaiden komponenttien membraanin läpäisystä saatuun mittausaineistoon. Toisaalta mallin ratkaisu vaatii luotettavan ratkaisustrategian, jossa hyötykäytetään kohteesta riippuvaa tietoa. Näitä kysymyksiä havainnollistettiin H2/CO2 seoksen erotuksessa MFI-zeoliitti-membraanilla korkeassa paineessa. Samoin seosten adsorboitumiskäyttäytymistä ennustettiin onnistuneesti pelkästään puhtaiden komponenttien adsorptiodatan pohjalta. Kokonaisuutena voidaan todeta, että tarkasteltujen erotusprosessimallien ennustavuutta voidaan parantaa yhdistämällä malli, jolla on selkeä ilmiöpohja ja luotettava ratkaisustrategia. Lisäksi mallien käytettävyys erotusprosessien suunnittelussa on parantunut työn tulosten pohjalta
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Schreiber, Heike Verfasser], André [Akademischer Betreuer] [Bardow, and Gerhard [Akademischer Betreuer] Schmitz. "Experiments and Validated Models for Adsorption Thermal Energy Storage in Industrial and Residential Applications / Heike Schreiber ; André Bardow, Gerhard Schmitz." Aachen : Universitätsbibliothek der RWTH Aachen, 2017. http://d-nb.info/1162450770/34.
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Betancourt, Angel E. "First principles calculations of the interaction of rare-gas atoms with transition metal surfaces." Thesis, University of Bath, 2000. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341150.
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Palli, Amar D. "Heteroatom removal from nonaqueous systems by sorption processes a comparative study of kinetic models." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179950186.
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Raymond, Alexander William. "Investigation of microparticle to system level phenomena in thermally activated adsorption heat pumps." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34682.
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Heat actuated adsorption heat pumps offer the opportunity to improve overall energy efficiency in waste heat applications by eliminating shaft work requirements accompanying vapor compression cycles. The coefficient of performance (COP) in adsorption heat pumps is generally low. The objective of this thesis is to model the adsorption system to gain critical insight into how its performance can be improved. Because adsorption heat pumps are intermittent devices, which induce cooling by adsorbing refrigerant in a sorption bed heat/mass exchanger, transient models must be used to predict performance. In this thesis, such models are developed at the adsorbent particle level, heat/mass exchanger component level and system level.
Adsorption heat pump modeling is a coupled heat and mass transfer problem. Intra-particle mass transfer resistance and sorption bed heat transfer resistance are shown to be significant, but for very fine particle sizes, inter-particle resistance may also be important. The diameter of the adsorbent particle in a packed bed is optimized to balance inter- and intra-particle resistances and improve sorption rate. In the literature, the linear driving force (LDF) approximation for intra-particle mass transfer is commonly used in place of the Fickian diffusion equation to reduce computation time; however, it is shown that the error in uptake prediction associated with the LDF depends on the working pair, half-cycle time, adsorbent particle radius, and operating temperatures at hand.
Different methods for enhancing sorption bed heat/mass transfer have been proposed in the literature including the use of binders, adsorbent compacting, and complex extended surface geometries. To maintain high reliability, the simple, robust annular-finned-tube geometry with packed adsorbent is specified in this work. The effects of tube diameter, fin pitch and fin height on thermal conductance, metal/adsorbent mass ratio and COP are studied. As one might expect, many closely spaced fins, or high fin density, yields high thermal conductance; however, it is found that the increased inert metal mass associated with the high fin density diminishes COP. It is also found that thin adsorbent layers with low effective conduction resistance lead to high thermal conductance. As adsorbent layer thickness decreases, the relative importance of tube-side convective resistance rises, so mini-channel sized tubes are used. After selecting the proper tube geometry, an overall thermal conductance is calculated for use in a lumped-parameter sorption bed simulation. To evaluate the accuracy of the lumped-parameter approach, a distributed parameter sorption bed simulation is developed for comparison. Using the finite difference method, the distributed parameter model is used to track temperature and refrigerant distributions in the finned tube and adsorbent layer. The distributed-parameter tube model is shown to be in agreement with the lumped-parameter model, thus independently verifying the overall UA calculation and the lumped-parameter sorption bed model.
After evaluating the accuracy of the lumped-parameter model, it is used to develop a system-level heat pump simulation. This simulation is used to investigate a non-recuperative two-bed heat pump containing activated carbon fiber-ethanol and silica gel-water working pairs. The two-bed configuration is investigated because it yields a desirable compromise between the number of components (heat exchangers, pumps, valves, etc.) and steady cooling rate. For non-recuperative two-bed adsorption heat pumps, the average COP prediction in the literature is 0.39 for experiments and 0.44 for models. It is important to improve the COP in mobile waste heat applications because without high COP, the available waste heat during startup or idle may be insufficient to deliver the desired cooling duty. In this thesis, a COP of 0.53 is predicted for the non-recuperative, silica gel-water chiller. If thermal energy recovery is incorporated into the cycle, a COP as high as 0.64 is predicted for a 90, 35 and 7.0°C source, ambient and average evaporator temperature, respectively. The improvement in COP over heat pumps appearing in the literature is attributed to the adsorbent particle size optimization and careful selection of sorption bed heat exchanger geometry.
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Silva, Flávio de Matos. "Estudo dos fenômenos de transporte em cromatografia através da aplicação de modelos de rede e estocásticos." Universidade do Estado do Rio de Janeiro, 2011. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=2753.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico<br>O estudo dos diferentes fenômenos de separação tem sido cada vez mais importante para os diferentes ramos da indústria e ciência. Devido à grande capacidade computacional atual, é possível modelar e analisar os fenômenos cromatográficos a nível microscópico. Os modelos de rede vêm sendo cada vez mais utilizados, para representar processos de separação por cromatografia, pois através destes pode-se representar os aspectos topológicos e morfológicos dos diferentes materiais adsorventes disponíveis no mercado. Neste trabalho visamos o desenvolvimento de um modelo de rede tridimensional para representação de uma coluna cromatográfica, a nível microscópico, onde serão modelados os fenômenos de adsorção, dessorção e dispersão axial através de um método estocástico. Também foram utilizadas diferentes abordagens com relação ao impedimento estérico Os resultados obtidos foram comparados a resultados experimentais. Depois é utilizado um modelo de rede bidimensional para representar um sistema de adsorção do tipo batelada, mantendo-se a modelagem dos fenômenos de adsorção e dessorção, e comparados a sistemas reais posteriormente. Em ambos os sistemas modelados foram analisada as constantes de equilíbrio, parâmetro fundamental nos sistemas de adsorção, e por fim foram obtidas e analisadas isotermas de adsorção. Foi possível concluir que, para os modelos de rede, os fenômenos de adsorção e dessorção bastam para obter perfis de saída similares aos vistos experimentalmente, e que o fenômeno da dispersão axial influência menos que os fenômenos cinéticos em questão<br>The study of different phenomena of separation has been most important for the different areas of industry and science. Due to the large computational available, we can model and analyze the chromatographic phenomena at the microscopic level. The network model has been most used to represent processes of separation by chromatography, because through them we are able represent the topological and morphological aspects of different adsorbent materials available on the market. In this work we aim at studying the dynamics of percolation chromatography through the phenomenology of adsorption, desorption and axial dispersion. In this work we aim to develop a three-dimensional network model representation of a chromatographic column, microscopic level, which will model the phenomena of adsorption, desorption and axial dispersion through a stochastic method. After that, a two-dimensional network model is used to represent a system of adsorption in batch, keeping the modeling of the adsorption / desorption, and then compare to real systems. In both systems modeled are analyzed the equilibrium constant, the basic parameter in the adsorption systems, and at the end are obtained and analyzed adsorption isotherms. We concluded for the network models the phenomena of adsorption and desorption were sufficient to obtain output profiles similar to those seen experimentally, the phenomenon of axial dispersion effect unless the kinetic phenomena in question.
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Bergkvist, Petra. "Long-term fate of sewage-sludge derived cadmium in arable soils : laboratory and field experiments, and modelling with SLAM and WHAM /." Uppsala : Dept. of Soil Sciences, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/a410.pdf.
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Biasse, Anselmo Domingos. "Modelos estocásticos e de rede no estudo de mecanismos de adsorção e difusão em adsorventes porosos." Universidade do Estado do Rio de Janeiro, 2009. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=1239.
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A compreensão dos fenômenos de adsorção e difusão em superfícies é fundamental no desenvolvimento de materiais de alto rendimento utilizados em uma série de processos de
grande relevância industrial. A modelagem de materiais adsorventes porosos através de modelos de rede tem seu potencial uma vez que se pode estudar os fenômenos a nível
microscópico incorporando uma série de parâmetros estatísticos importantes na compreensão dos mecanismos nessa escala. Neste trabalho de dissertação de mestrado, em um primeiro
momento, foram utilizadas redes bidimensionais quadradas com abordagem de percolação de sítio-sítio para modelar superfícies sujeitas às condições de adsorção em tempo infinito, com
o intuito de se estudar as isotermas de adsorção em processos batelada. Numa primeira parte foi observada uma relação estatística na determinação das isotermas de adsorção, em que a probabilidade de adsorção estava condicionada ao número de moléculas na fase líquida. Na segunda parte foram incorporados diferentes tipos e tamanhos de moléculas, sendo observados diferentes comportamentos das isotermas de adsorção de acordo com a variação dessas moléculas adsorvidas. Outro fenômeno de interesse foi o estudo do Limiar de Percolação utilizando diferentes tipos e tamanhos de moléculas, sendo observados comportamentos específicos para cada caso. Desta forma, pode-se obter parâmetros das isotermas relacionados com os tipos e tamanhos moleculares estudados, sendo observado uma forte dependência daqueles com o tamanho da molécula, uma vez que a seletividade à adsorção aumenta com o tamanho da molécula. Ainda nesta primeira parte foram calculados também a probabilidade de ocupação relacionada com a entropia, observando comportamentos na probabilidade de ocupação a cada etapa de tempo. Em um segundo
momento, foi estudado a dinâmica de difusão, mediante random walk ou passeadores aleatórios, em redes quadradas e cúbicas, em que foram obtidas leis de potência para cada
dimensão. Aspectos como dispersão axial e porosidade foram incorporadas nas simulações, sendo abservados comportamentos específicos para cada caso.
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Di, Biase Emanuela. "Systematic development of predictive molecular models of high surface area activated carbons for the simulation of multi-component adsorption processes related to carbon capture." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/16155.
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Adsorption in porous materials is a promising technology for CO2 capture and storage. Particularly important applications are adsorption separation of streams associated with the fossil fuel power plants operation, as well as natural gas sweetening. High surface area activated carbons are a promising family of materials for these applications, especially in the high pressure regimes. As the streams under consideration are generally multi-component mixtures, development and optimization of adsorption processes for their separation would substantially benefit from predictive simulation models. In this project we combine experimental data and molecular simulations to systematically develop a model for a high surface area carbon material, taking activated carbon Maxsorb MSC-30 as a reference. Our study starts from the application of the well-established slit pore model, and then evolves through the development of a more realistic model, based on a random packing of small graphitic fragments. In the construction of the model, we introduce a number of constraints, such as the value of the accessible surface area, concentration of the surface groups and pore volume, to bring the properties of the model structure close to the reference porous material. Once a plausible model is developed, its properties are further tuned through comparison between simulated and experimental results for carbon dioxide and methane. The model is then validated by predictions for the same species at different conditions and by prediction of other species involved in the carbon capture processes. The model is applied to simulate the separations involved in pre and post combustion capture processes and sweetening of sour natural gas, using realistic conditions and compositions for the multicomponent mixtures. Finally, it is used to explore the effect of water in pre and post combustion separations.
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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.<br>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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Manzi, Berardo Mario. "Computer simulations of Red Blood Cells and proteins interacting with nanostructured surfaces." Doctoral thesis, Universitat Rovira i Virgili, 2018. http://hdl.handle.net/10803/665072.
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Les propietats físiques de les superfícies antimicrobianes s'han estudiat mitjançant dos models teòrics diferents. El primer enfocament, Random Sequential Adsorption (RSA), descriu el primer pas de qualsevol entitat estrangera que entri al cos humà: adsorció de proteïnes. Demostrem que les propietats bactericides de les superfícies nanoestructurades no es veuen compromeses amb la colonització de la proteïna més abundant en sang, l'Albúmina de sèrum humà. A aquest efecte, desenvolupem una extensió a RSA per fer front a geometries complexes, i utilitzar-les per provar diferents superfícies de models.
El segon enfocament estudia la interacció real de les cel·les amb aquestes superfícies. Utilitzem dinàmiques moleculars de gra gruixut per investigar les cèl·lules vermelles de la sang, que representen un compromís òptim entre simplicitat computacional i modelització realista, a més de ser motiu de preocupació per l'aplicabilitat de les superfícies antimicrobianes en la medicina, a causa de la ruptura de la membrana observada en experiments. Demostrem que la ruptura no és causada per la perforació dels cims de les superfícies, sinó per les importants deformacions que condueixen a l'excés d'extensió. Aquest efecte es pot disminuir variant el disseny de les superfícies, en particular les seves dimensions.<br>Las propiedades físicas de las superficies antimicrobianas se han estudiado utilizando dos modelos teóricos diferentes. El primer enfoque, la Adsorción Secuencial Aleatoria (RSA), describe el primer paso de cualquier entidad extraña que ingrese al cuerpo humano: la adsorción de proteínas. Demostramos que las propiedades bactericidas de las superficies nanoestructuradas no se ven comprometidas tras la colonización de la proteína más abundante en la sangre, la albúmina sérica humana. Para este propósito, desarrollamos una extensión a RSA para tratar geometrías complejas, y lo usamos para probar varias superficies de modelos diferentes.
El segundo enfoque estudia la interacción real de las células con dichas superficies. Utilizamos la dinámica molecular de grano grueso para investigar los glóbulos rojos, que representan un compromiso óptimo entre simplicidad computacional y modelado realista, además de ser motivo de preocupación por la aplicabilidad de las superficies antimicrobianas en medicina, debido a la rotura de la membrana observada en los experimentos. Demostramos que la ruptura no es causada por la perforación de los picos en las superficies, sino más bien por las importantes deformaciones que conducen a la sobreextensión. Este efecto puede disminuirse variando el diseño de las superficies, en particular sus dimensiones.<br>Physical properties of antimicrobial surfaces have studied using two different theoretical models. The first approach, Random Sequential Adsorption (RSA), describes the first step of any foreign entity entering the human body: protein adsorption. We demonstrate that the bactericidal properties of nanostructured surfaces are not compromised upon colonisation of the most abundant protein in blood, Human Serum Albumin. For this purpose, we develop an extension to RSA to deal with complex geometries, and use it to test several different model surfaces.
The second approach studies the actual interaction of cells with said surfaces. We use Coarse-grained Molecular Dynamics to investigate Red Blood Cells, which represent an optimal compromise between computational simplicity and realistic modelling, in addition to be cause of concern for the applicability of antimicrobial surfaces in medicine, due to the membrane rupture observed in experiments. We demonstrate that the rupture is not caused by the piercing of the peaks on the surfaces, but rather by the important deformations leading to over-extension. This effect can be diminished by varying the design of the surfaces, in particular their dimensions.
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Stachiw, Rosalvo. "Modelagem e simulação do processo de adsorção de compostos orgânicos em xisto, catalisador exaurido de FCC e carvão ativado em pó." Universidade Tecnológica Federal do Paraná, 2008. http://repositorio.utfpr.edu.br/jspui/handle/1/135.
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O alto custo do carvão ativado tem motivado a busca por materiais adsorvedores de baixo custo, como os subprodutos industriais. Neste sentido, o uso dos subprodutos industriais de xisto: finos de xisto (XC), xisto retortado (XR) e xisto retortado com pneus (XRP), proveniente do processo PETROSIX/PETROBRAS, e o catalisador exaurido (CAT), da unidade de FCC (Craqueamento Catalítico em Leito Fluidizado), foram caracterizados e utilizados neste trabalho na adsorção de compostos orgânicos de efluente líquido industrial. O objetivo geral deste estudo é modelar matematicamente o processo de adsorção de compostos orgânicos em xisto, catalisador exaurido de FCC e carvão ativado em pó, utilizando o modelo HSDM (Modelo de Difusão por Superfície Homogênea), e o comportamento hidráulico do sistema adsorvedor. A caracterização estrutural e química de várias amostras de xisto (finos de xisto, xisto retortado e xisto retortado com pneus) e do catalisador exaurido de FCC, além do desenvolvimento de um modelo computacional para a simulação do processo de adsorção são contribuições adicionais ao trabalho. Os resultados de caracterização dos adsorventes de xisto mostram que estes materiais são basicamente macroporosos e com área superficial em torno de 0,51 a 3,36 2 . 1 m g , além de apresentarem as mesmas estruturas cristalinas, e micrografias características dos argilominerais. Já o adsorvente CAT mostrou-se formado basicamente por faujasita, sílica e alumina, apresentando-se na forma de grânulos esféricos, irregulares e microporosos, com área superficial característica de materiais zeolíticos (148 e 155 2 . 1 m g ). Os ensaios de adsorção realizados nos efluentes sintéticos e industriais (Fenólico e Petroquímico) mostraram que existe potencial de aplicação dos subprodutos industriais de xisto e CAT na remoção de compostos orgânicos (corantes, fenóis e COT) destes efluentes. Os resultados das simulações obtidos do modelo proposto mostraram que o tratamento unicamente por adsorção em xisto ou CAT, tendo em vista os padrões ambientais de descarte de efluente (resolução CONAMA 357), é inviável. Isto por que a quantidade de adsorvente requerida é muito elevada. Entretanto, tais adsorventes podem ser utilizados na redução da carga orgânica de ambos os efluentes. Por questões de transporte, é indicado que cada subproduto industrial seja utilizado na própria indústria que lhe deu origem. Ou seja, o CAT é indicado para o tratamento do efluente Petroquímico e os adsorventes de xisto para o Fenólico.<br>The high cost of the activated carbon has motivated the search of low cost adsorbents such as industrial by-products. In this sense, the use of industrial by-products of oil shale: Oil Shale (XC), Pirolized Oil Shale (XR) and Pirolized Oil Shale with Tires (XRP), from PETROSIX/PETROBRAS, and the spent catalyst (CAT), from FCC (Fluid Catalytic Cracking) unit were characterized and used in this work in the adsorption of organics compounds of industrial liquid effluent. The main contribution of this thesis is to propose a mathematical model to the adsorption process of organic compounds in oil shale, spent catalyst of FCC and powdered activated carbon. This model is based on HSDM (Homogeneous Surface Diffusion Model) model and on the hydraulic behavior of the adsorbent system. Other contribution is the structural and chemical characterization of several samples of oil shale (oil shale, Pirolized oil shale and Pirolized oil shale with Tires) and of the spent catalyst of FCC. A computational model to simulate the adsorption process of these materials is also developed and can be considered an additional contribution of this work. Experimental and simulated results allow characterization of the oil shale adsorbent as basically macroporous and with superficial area about 0.51 to 3.36 m2.g-1. In addition, they present the same crystal structures and clay micrografies characteristics. The adsorbent CAT is composed basically by Faujasite, silica and alumina. They present spherical beads, irregular forms and micropores, with superficial area characteristics of zeolitic materials (148 and 155 m2.g-1). The adsorption tests realized in the synthetic and industrial effluents (Phenolic and Petrochemical) showed the potential of application of the industrial by-products of oil shale and CAT in the removal of organics compounds (dyes, Phenol and COT) of these effluents. In respect of environmental standards to effluents disposal (CONAMA resolution 357), simulations results, obtained with the proposed model, has demonstrated that the use of only oil shale or CAT is not viable, because the high quantity of adsorbents required. However, such adsorbents can be used in the reduction of organic loads in both effluents, when combined with other processes. Each adsorbent showed be used where it is produced because of transportation cost. The CAT is indicated for the treatment of Petrochemical effluent while the others adsorbents may be applied in the phenolic effluent treatment.
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Taillon, Kate. "Modeling surface complexation relationships in forest and agricultural soil." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82435.
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The adsorption behaviour of trace metals in soil may provide us with a way to more accurately predict and assess the toxicity of metals in the environment. This thesis reports efforts to apply surface complexation modeling to agricultural and forest soil and to relate model parameters to common soil properties. This study considered Ca, Cd, Cu, Pb and Zn but the methods here could be applied to other metals. In Chapter 2, the surface charge and adsorption behaviour of a set of Ap horizons was characterised using back-titration and batch adsorption techniques. With the objective of simplifying the application of the NICCA model to surface charge and cation adsorption in whole soils the parameters of the NICCA model were related to soil properties (Chapter 3). Four of the six surface charge parameters could be predicted from soil properties and this enabled me to reasonably predict the surface charge of a second group of soils from soil properties. These results suggest that it is possible to make reasonable predictions about the surface charge and adsorption behaviour of a given type of soil using some easily measurable soil properties and a set of generic NICCA adsorption parameters for that soil type. In Chapter 4 this idea is applied to the determination of lime requirement for the agricultural soils.
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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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Dureckova, Hana. "Robust Machine Learning QSPR Models for Recognizing High Performing MOFs for Pre-Combustion Carbon Capture and Using Molecular Simulation to Study Adsorption of Water and Gases in Novel MOFs." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37288.
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Metal organic frameworks (MOFs) are a class of nanoporous materials composed through self-assembly of inorganic and organic structural building units (SBUs). MOFs show great promise for many applications due to their record-breaking internal surface areas and tunable pore chemistry. This thesis work focuses on gas separation applications of MOFs in the context of carbon capture and storage (CCS) technologies. CCS technologies are expected to play a key role in the mitigation of anthropogenic CO2 emissions in the near future. In the first part of the thesis, robust machine learning quantitative structure-property relationship (QSPR) models are developed to predict CO2 working capacity and CO2/H2 selectivity for pre-combustion carbon capture using the most topologically diverse database of hypothetical MOF structures constructed to date (358,400 MOFs, 1166 network topologies). The support vector regression (SVR) models are developed on a training set of 35,840 MOFs (10% of the database) and validated on the remaining 322,560 MOFs. The most accurate models for CO2 working capacities (R2 = 0.944) and CO2/H2 selectivities (R2 = 0.876) are built from a combination of six geometric descriptors and three novel y-range normalized atomic-property-weighted radial distribution function (AP-RDF) descriptors. 309 common MOFs are identified between the grand canonical Monte Carlo (GCMC) calculated and SVR-predicted top-1000 high-performing MOFs ranked according to a normalized adsorbent performance score. This work shows that SVR models can indeed account for the topological diversity exhibited by MOFs.
In the second project of this thesis, computational simulations are performed on a MOF, CALF-20, to examine its chemical and physical properties which are linked to its exceptional water-resisting ability. We predict the atomic positions in the crystal structure of the bulk phase of CALF-20, for which only a powder X-ray diffraction pattern is available, from a single crystal X-ray diffraction pattern of a metastable phase of CALF-20. Using the predicted CALF-20 structure, we simulate adsorption isotherms of CO2 and N2 under dry and humid conditions which are in excellent agreement with experiment. Snapshots of the CALF-20 undergoing water sorption simulations reveal that water molecules in a given pore adsorb and desorb together due to hydrogen bonding. Binding sites and binding energies of CO2 and water in CALF-20 show that the preferential CO2 uptake at low relative humidities is driven by the stronger binding energy of CO2 in the MOF, and the sharp increase in water uptake at higher relative humidities is driven by the strong intermolecular interactions between water.
In the third project of this thesis, we use computational simulations to investigate the effects of residual solvent on Ni-BPM’s CH4 and N2 adsorption properties. Single crystal X-ray diffraction data shows that there are two sets of positions (Set 1 and 2) that can be occupied by the 10 residual DMSO molecules in the Ni-BPM framework. GCMC simulations of CH4 and N2 uptake in Ni-BPM reveal that CH4 uptake is in closest agreement with experiment when the 10 DMSO’s are placed among the two sets of positions in equal ratio (Mixed Set). Severe under-prediction and over-prediction of CH4 uptake are observed when the DMSO’s are placed in Set1 and Set 2 positions, respectively. Through binding site analysis, the CH4 binding sites within the Ni-BPM framework are found to overlap with the Set 1 DMSO positions but not with the Set 2 DMSO positions which explains the deviations in CH4 uptake observed for these cases. Binding energy calculations reveal that CH4 molecules are most stabilized when the DMSO’s are in the Mixed Set of positions.
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Keskin, Seda. "Accelerating development of metal organic framework membranes using atomically detailed simulations." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31679.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010.<br>Committee Chair: Sholl, David S.; Committee Member: Chance, Ronald R.; Committee Member: Jang, Seung Soon; Committee Member: Koros, William J.; Committee Member: Nair, Sankar. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Undin, Torgny. "Development and improvement of methods for characterization of HPLC stationary phases." Licentiate thesis, Uppsala universitet, Analytisk kemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-166978.
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High Performance Liquid Chromatography (HPLC) is a widely used tech-nique both for detecting and purifying substances in academy and in the industry. In order to facilitate the use of, and knowledge in HPLC, character-ization of stationary phases is of utmost importance. Tailor made characteri-zation methods and workflows are steadily increasing the speed and accura-cy in which new separation systems and methods are developed. In the field fundamental separation science and of preparative chromatography there is always the need for faster and more accurate methods of adsorption isotherm determination. Some of that demand are met with the steadily increase of computational power, but the practical aspects on models and methods must also be further developed. These nonlinear characterization methods will not only give models capable of describing the adsorption isotherm but also actual values of local adsorption energies and monolayer saturation capacity of an individual interaction sites etc.The studies presented in this thesis use modern alkali stable stationary phas-es as a model phase, which will give an insight in hybrid materials and their separation mechanism. This thesis will include an update and expansion in using the Elution by Characteristic Points (ECP) method for determination of adsorption isotherms. The precision is even further increased due to the ability to use slope data as well as an increase in usability by assigning a set of guidance rules to be applied when determine adsorption isotherms having inflection points. This thesis will further provide the reader with information about stationary phase characterization and the power of using existing tech-niques; combine them with each other, and also what the expansion of meth-ods can revile in terms of precision and increased usability. A more holistic view of what benefits that comes with combining a non-linear characteriza-tion of a stationary phase with more common linear characterization meth-ods are presented.
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Wissmann, Paul J. "Simultaneous approach to model building and process design using experimental design application to chemical vapor deposition /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26543.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009.<br>Committee Chair: Grover, Martha; Committee Member: Garmestani, Hamid; Committee Member: Hess, Dennis; Committee Member: McDowell, David; Committee Member: Nenes, Athanasios; Committee Member: Realff, Matthew. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Yao, Hong Mei. "Wavelet based dynamic modelling of simulated moving bed chromatographic processes." Thesis, Curtin University, 2009. http://hdl.handle.net/20.500.11937/1918.
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Simulated moving bed chromatography process (SMBCP) is the technical realisation of a countercurrent adsorption process through the cyclic port switching. SMB technology reduces the cost of packing material with high loading capacity and provides high purity and high recovery in a very short time. Major commodity applications have been found in the petroleum, food, biotechnology, pharmaceutical and fine chemical industries. The industrial applications bring an emergent demand to improve the SMBCP operation for higher product quality, productivity, efficiency and robustness. However, for this particular process, we encounter several challenges. Firstly, the interplay of the effects of strong nonlinearities, competition of solutes, mass transfer resistance and fluid dynamic dispersion produces steep concentration fronts. Mathematical model accounted for this particular property constitutes a serious difficulty for the solution procedure. Secondly, a dynamic SMB model consists of a set of partial differential, ordinary differential and algebraic equations, which are highly coupled. The large size is a problem due to its intensive computation when on-line optimisation and real-time control are necessary. Thirdly, the SMB unit operation exhibits complex dynamics. Process metrics for design and operation can be determined only when a cyclic steady state is reached after a certain number of switching. Achieving this steady state by solving the PDE models cycle after cycle involves expensive calculation. Studies have been carried out to solve these problems through process analysis, investigation on spatial discretisation techniques, and development of an accelerated integration scheme.Through a systematic study on the advances of SMB modelling, design and control, a set of functionally equivalent models for SMBCP are identified and summarized for their practical applications. The limitations of the existing modelling techniques in industrial applications are also identified. Furthermore, structural analysis of the existing models is conducted for a better understanding of the functionality and suitability of each model. Suggestions are given on how to choose an appropriate model with sufficient accuracy while keeping the computational demand reasonably low for real time control.Effort is made on to the systematic investigation of different numerical methods for the solution of PDEs to circumvent the steep gradients encountered in chromatographic separation. Comprehensive studies are conducted on a single column chromatographic process represented by a transport-dispersive-equilibrium linear model. Numerical solutions from the upwind-1 finite difference, wavelet-collocation, and high resolution methods are evaluated by quantitative comparisons with the analytical solution for a range of Peclet numbers. It reveals that for a PDE system with a low Peclet number, all existing numerical methods work well, but the upwind finite difference method consumes the most time for the same degree of accuracy of the numerical solution. The high resolution method provides an accurate numerical solution for a PDE system with a medium Peclet number. The wavelet collocation method is capable of catching up steep changes in the solution, and thus can be used for solving PDE models with high singularity.The advantages and disadvantages of the wavelet based approaches are further investigated through several case studies on real SMBCP system. A glucose-fructose separation process is firstly chosen with its relatively simple isotherm representations. Simulations are conducted using both wavelet collocation and upwind finite difference methods. For more complicated applications, an enantiomers separation process is selected. As the PDEs model exhibit a certain degree of singularity, wavelet collocation and high resolution methods are adopted for spatial discretisation. It is revealed that both the wavelet based approaches and high resolution methods are good candidates in terms of computation demand and prediction accuracy on the steep front. This is the first time that these two frontier numerical methods are used for such a complex SMB system models and our results are encouraging for the development of model-based online control scheme.In developing a new scheme to rapidly obtain the solution at steady state for any arbitrary initial condition, the concept of Quasi-Envelope (QE) is adopted under the consideration that a SMBCP can be treated as a pseudo-oscillatory process because of a large number of continuous switching. The scheme allows larger steps to be taken to predict the slow change of starting state within each switching. Combined with previously developed wavelet-based technique, this method is successfully applied to the simulation of a SMB sugar separation process. Investigations are also carried out on the location of proper starting point for the algorithm and on the effect of changing stepsize to the convergence of iteration method. It is found that if the starting state of Quasi-Envelope is chosen to be the same as the original function, the multivalue algorithm would require similar computational effort to achieve the steady state prediction, regardless of the integration stepsize. If using constant stepsize, launching QE later is helpful when quasi-envelope displays steep change at the start-up period. A changing stepsize produces slow convergence compared to the constant stepsize strategy, thus increasing the work load where the stepsize change is occurring. Other iteration method is required to be imposed to achieve faster convergence right from the beginning. Potential applications can be seen for other chemical engineering processes with inherent cyclic behaviour.