Tesis sobre el tema "Adsorption optimization"

Periodic Adsorption Processes (PAPs) have gained increasing commercial importance asan energy-efficient separation technique over the past two decades. Based on fluid-solidinteractions, these systems never reach steady state. Instead they operate at cyclic steadystate, where the bed conditions at the beginning of the cycle match with those at the endof the cycle. Nevertheless, optimization of these processes remains particularly challenging,because cyclic operation leads to dense Jacobians, whose computation dominatesthe overall cost of the optimization strategy. In order to efficiently handle these Jacobiansduring optimization and reduce the computation time, this work presents newcomposite step trust-region algorithms based on sequential quadratic programming andinterior point methods for the solution of minimization problems with both nonlinearequality and inequality constraints. Instead of forming and factoring the dense constraintJacobian, these algorithms approximate the Jacobian of equality constraints with a specializedquasi-Newton method. Hence, they are well suited to solve optimization problemsrelated to PAPs. In addition to allowing inexactness of the Jacobian and its null-spacerepresentation, the algorithm also provides exact second order information in the formof Hessian-vector products to improve the convergence rate. The resulting approachalso combines automatic differentiation and more sophisticated integration algorithms toevaluate the direct sensitivity and adjoint sensitivity equations. Numerical performance results on small scale PAP problems and CUTEr problems show significant reduction incomputation time. Furthermore, we propose a systematic methodology to design PSA cycles using asuperstructure based approach. The superstructure is rich enough to predict a numberof different PSA operating steps, and their optimal sequence is obtained by solving anoptimal control problem. PSA is a potential technology for pre-combustion CO2 capturebecause of low operating costs and high performance. We utilize the superstructureapproach to synthesize PSA cycles for this purpose which can separate both H2 andCO2 at high purity and operate with a low power consumption of 86 kWh/tonne of CO2captured.

[EN] This PhD study deals with the modelling of an adsorption system designed to provide air conditioning for vehicles, and is driven by the waste heat available from the water/glycol cooling circuit of the engine. The system is based on the sequential heating/cooling of two sorption beds containing a solid sorption material which desorbs or adsorbs water vapour. The condensation of the vapour is carried out by a cooling circuit while the subsequent evaporation of the condensed liquid is employed to produce the cooling effect, generating chilled water, which is then employed to cool down the air of the cabin. The developed model is fully dynamic and is based on zero-dimensional lumped parameter models for all the necessary components of the overall system including the engine, the beds, the heating circuit, the cooling circuit, the chilled water circuit and the vehicle cabin. The sorption bed model takes into account the non-equilibrium of the adsorption and desorption processes and is able to work with any kind of adsorbent materials, but the study has been restricted to silica gel and zeolite which are among the most appropriate materials for this application. The model is employed to simulate a standard driving cycle of a vehicle, evaluating the instantaneous available heat from the engine cooling system and the dynamic behaviour of the described sorption A/C system, resulting in the estimation of the evolution of the cabin temperature along the cycle. The model of the overall system has been developed under the MATLAB Simulink programming environment. The model of the adsorption system has been first validated against experimental results, showing its excellent capabilities to predict the dynamic behaviour of the system. The model was then used to analyse the influence of the main design parameters of the bed and the main operation parameters on the system's performance: cooling capacity and coefficient of performance (COP). This was done in order to provide rules for the optimal design and operation of this kind of systems. Finally, the model has been employed to analyse the overall system (engine, adsorption system, heating and cooling circuits, chilled water circuit and cabin) performance along a standard driving cycle, under various operation strategies with regards to the initial state of the adsorbent material in the beds, and operation conditions both for a car and a truck. The results show the difficulties of activating the system at the initial periods of the cycle, when the engine is warming up, and the difficulties to synchronise the operation of the system with the availability of waste energy. They also highlight the limitation in capacity of the designed system, showing that it would not able to fulfil the comfort requirements inside the cabin in hot days or after soaking conditions. Part of this PhD study was carried out in the frame of an R&D project called "Thermally Operated Mobile Air Conditioning Systems - TOPMACS", financially supported by the EU under the FP6 program, which was devoted to the evaluation of the feasibility and performance of potential sorption system solutions for the air conditioning of vehicles.
[ES] Esta tesis doctoral se centra en el modelado de un sistema de adsorción diseñado para proporcionar aire acondicionado de vehículos a partir del calor residual disponible en el circuito de refrigeración de agua/glicol del motor. El sistema se basa en el calentamiento/enfriamiento secuencial de dos reactores que contienen un material adsorbente sólido que desorbe o absorbe vapor de agua. La condensación del vapor se lleva a cabo mediante un circuito de refrigeración, mientras que la posterior evaporación del agua condensada se emplea para producir agua fría, que se emplea finalmente en enfriar el aire de la cabina. El modelo desarrollado es completamente dinámico y se basa en modelos cero dimensionales de parámetros concentrados, para todos y cada uno de los componentes del sistema global incluyendo el motor, los reactores, el circuito de calentamiento, el circuito de enfriamiento, el circuito de agua fría y la cabina del vehículo. El modelo del reactor contempla el no equilibrio de los procesos de adsorción o desorción y es capaz de trabajar con cualquier par de materiales adsorbentes. No obstante el estudio se ha restringido a gel de sílice y zeolita que se encuentran entre los materiales más adecuados para esta aplicación. El modelo se emplea para simular un ciclo de conducción estándar del vehículo, evaluando el calor disponible instantáneamente en el sistema de refrigeración del motor, y el comportamiento dinámico del sistema descrito adsorción-Aire Acondicionado, permitiendo como resultado principal la estimación de la evolución de la temperatura de la cabina a lo largo el ciclo. El modelo del sistema global se ha desarrollado en el marco del entorno de programación MATLAB Simulink. El modelo del sistema de adsorción se ha validado primero contra resultados experimentales demostrando las excelentes capacidades del modelo para predecir el comportamiento dinámico del sistema. A continuación, el modelo se ha aplicado para analizar la influencia de los principales parámetros de diseño del reactor, y de los principales parámetros de operación, sobre el rendimiento del sistema: la capacidad y coeficiente de operación (COP), con el fin de proporcionar directrices para el diseño y operación óptima de este tipo de sistemas. Por último, el modelo ha sido empleado para analizar el funcionamiento y prestaciones del sistema en su conjunto (motor, sistema de absorción, los circuitos de calefacción y refrigeración, circuito de agua fría, y la cabina) a lo largo de un ciclo de conducción estándar, bajo diferentes estrategias de operación en lo que se refiere al estado inicial del material adsorbente en los reactores, y las condiciones de operación, para el caso de un coche, y para el de un camión. Los resultados muestran las dificultades de la activación del sistema en los periodos iniciales del ciclo, cuando el motor se está calentando, y las dificultades para sincronizar el funcionamiento del sistema con la disponibilidad de energía térmica excedente del motor, así como la limitación en la capacidad de enfriamiento del sistema diseñado, que no resulta capaz de satisfacer los requerimientos mínimos de confort dentro de la cabina en los días calurosos o de enfriarlo con suficiente rapidez cuando el vehículo ha estado estacionado bajo el sol durante varias horas. Parte de este estudio de doctorado se ha llevado a cabo en el marco de un proyecto de I + D denominado " Thermally Operated Mobile Air Conditioning Systems - TOPMACS", financiado parcialmente por la UE en el marco del programa FP6, y que perseguía la evaluación de la viabilidad y el potencial de aplicación de soluciones de sistemas de adsorción activadas por el calor residual del motor para el aire acondicionado de vehículos.
[CAT] Aquesta tesi doctoral es centra en el model d'un sistema d'adsorció dissenyat per a proporcionar aire acondicionat a vehicles a partir de la calor residual disponible al circuit de refrigeració d'aigua / glicol del motor. El sistema es basa en l'escalfament / refredament seqüencial de dos reactors que contenen un material adsorbent sòlid que desorbeix o absorbeix vapor d'aigua. La condensació del vapor es porta a terme mitjançant un circuit de refrigeració, mentre que la posterior evaporació de l'aigua condensada s'utilitza per a produir aigua freda, que s'empra finalment en refredar l'aire de la cabina. El model desenvolupat és completament dinàmic i es basa en models zero dimensionals de paràmetres concentrats, per a tots i cada un dels components del sistema global incloent el motor, els reactors, el circuit d'escalfament, el circuit de refredament, el circuit d'aigua freda i la cabina del vehicle. El model del reactor contempla el no equilibri dels processos d'adsorció o desorció i és capaç de treballar amb qualsevol parell de materials adsorbents. No obstant això, l'estudi s'ha restringit a gel de sílice i zeolita que es troben entre els materials més adequats per a aquesta aplicació. El model s'utilitza per a simular un cicle de conducció estàndard del vehicle, avaluant la calor disponible instantàniament en el sistema de refrigeració del motor, i el comportament dinàmic del sistema descrit Adsorció-Aire Acondicionat, permetent com a resultat principal l'estimació de l'evolució de la temperatura de la cabina al llarg del cicle. El model del sistema global s'ha desenvolupat en l'entorn de programació MATLAB Simulink. El model del sistema d'adsorció s'ha validat primer amb resultats experimentals demostrant les excel¿lents capacitats del model per a predir el comportament dinàmic del sistema. A continuació, el model s'ha aplicat per analitzar la influència dels principals paràmetres de disseny del reactor, i dels principals paràmetres d'operació, sobre el rendiment del sistema: la capacitat i coeficient d'operació (COP), amb la finalitat de proporcionar directrius per al disseny i operació òptima d'aquest tipus de sistemes. Finalment, el model ha estat utilitzat per analitzar el funcionament i prestacions del sistema en el seu conjunt (motor, sistema d'absorció, els circuits de calefacció i refrigeració, circuit d'aigua freda, i la cabina) al llarg d'un cicle de conducció estàndard, sota diferents estratègies d'operació pel que fa a l'estat inicial del material adsorbent en els reactors, i les condicions d'operació, per al cas d'un cotxe, i per al d'un camió. Els resultats mostren les dificultats de l'activació del sistema en els períodes inicials del cicle, quan el motor s'està escalfant, i les dificultats per sincronitzar el funcionament del sistema amb la disponibilitat d'energia tèrmica excedent del motor, així com la limitació en la capacitat de refredament del sistema dissenyat, que no resulta capaç de satisfer els requeriments mínims de confort dins de la cabina en els dies calorosos o de refredar amb suficient rapidesa quan el vehicle ha estat estacionat sota el sol durant diverses hores. Part d'aquest estudi de doctorat s'ha dut a terme en el marc d'un projecte d'I + D denominat "Thermally Operated Mobile Air Conditioning Systems - TOPMACS", finançat parcialment per la UE en el marc del programa FP6, i que perseguia l'avaluació de la viabilitat i el potencial d'aplicació de solucions de sistemes d'adsorció activats per la calor residual del motor per a l'aire condicionat de vehicles.
Verde Trindade, M. (2015). MODELLING AND OPTIMIZATION OF AN ADSORPTION COOLING SYSTEM FOR AUTOMOTIVE APPLICATIONS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/54120
TESIS

This study examines the combined treatment processes of air stripping and activated carbon adsorption for removing carbon tetrachloride, trichloroethylene and 1,4 dichlorobenzene from groundwater. Air stripping was used as a pretreatment with activated carbon as a polishing step. Optimization is achieved by determining the minimum operating and amortization costs for the variables of packing media depth versus carbon usage rate. A simplified design example illustrates the method of determining the optimum combination of treatment processes for the compounds and concentrations examined. The study included laboratory experiments which examined the air stripping performance of two different packing media as well as developing activated carbon isotherms. The transfer unit model was utilized to estimate the overall liquid mass transfer coefficient (KLa) for all three compounds at all experimental points.

>Magister Scientiae - MSc
Membrane Capacitive Deionisation (MCDI) is a technology used to desalinate water where a potential is applied to an electrode made of carbonaceous materials resulting in ion adsorption. Processes and materials for the production of electrodes to be applied in Membrane Capacitive Deionisation processes were investigated. The optimal electrode composition and synthesis approached was determined through analysis of the salt removal capacity and the rate at which the electrodes absorb and desorb ions. To determine the conductivity of these electrodes, the four point probe method was used. Contact angle measurements were performed to determine the hydrophilic nature of the electrodes. N2 adsorption was done in order to determine the surface area of carbonaceous materials as well as electrodes fabricated in this study. Scanning electron microscopy was utilised to investigate the morphology. Electrodes were produced with a range of research variables; (i) three different methods; slurry infiltration by calendaring, infiltration ink dropwise and spray-coating, (ii) electrodes with two different active material/binder ratios and a constant conductive additive ratio were produced in order to find the optimum, (iii) two different commercially available activated carbon materials were used in this study (YP50F and YP80F), (iv) two different commercially available electrode substrates were utilised (JNT45 and SGDL), (v) different slurry mixing times were investigated showing the importance of mixing, and (vi) samples were treated at three different temperatures to establish the optimal drying conditions. Through optimization of the various parameters, the maximum adsorption capacity of the electrode was incrementally increased by 36 %, from 16 mg·g-1 at the start of the thesis to 25 mg·g-1 at the end of the study.

Adsorption separation processes are extremely important to the chemical industry, especially in the manufacturing of food, pharmaceutical, and fine chemical products. This work addresses three main topics: first, systematic decision-making between rival gas phase adsorption processes for the same separation problem; second, process development for liquid phase simulated moving bed chromatography (SMB); third, accelerated startup for SMB units. All of the work in this thesis uses model-based optimization to answer complicated questions about process selection, process development, and control of transient operation. It is shown in this thesis that there is a trade-off between productivity and product recovery in the gaseous separation of enantiomers using SMB and pressure swing adsorption (PSA). These processes are considered as rivals for the same separation problem and it is found that each process has a particular advantage that may be exploited depending on the production goals and economics. The processes are compared on a fair basis of equal capitol investment and the same multi-objective optimization problem is solved with equal constraints on the operating parameters. Secondly, this thesis demonstrates by experiment a systematic algorithm for SMB process development that utilizes dynamic optimization, transient experimental data, and parameter estimation to arrive at optimal operating conditions for a new separation problem in a matter of hours. Comparatively, the conventional process development for SMB relies on careful system characterization using single-column experiments, and manual tuning of operating parameters, that may take days and weeks. The optimal operating conditions that are found by this new method ensure both high purity constraints and optimal productivity are satisfied. The proposed algorithm proceeds until the SMB process is optimized without manual tuning. In some case studies, it is shown with both linear and nonlinear isotherm systems that the optimal performance can be reached in only two changes of operating conditions following the proposed algorithm. Finally, it is shown experimentally that the startup time for a real SMB unit is significantly reduced by solving model-based startup optimization problems using the SMB model developed from the proposed algorithm. The startup acceleration with purity constraints is shown to be successful at reducing the startup time by about 44%, and it is confirmed that the product purities are maintained during the operation. Significant cost savings in terms of decreased processing time and increased average product concentration can be attained using a relatively simple startup acceleration strategy.

Die vorliegende Arbeit behandelt die Entwicklung des genetischen Starrkörper-Algorithmus (rigid body genetic algorithm, RGBA), und seine Anwendung zur Untersuchung der Kohlenwasserstoff-Adsorption auf der MgO (001) Oberfläche. Die RBGA Methode ist ein modifizierter hybrid-genetischer Algorithmus mit Starrkörper-Optimierung im lokalen Optimierungsschritt. Diese Modifikation führt zu einer großen Vereinfachung des Optimierungsproblems und ermöglicht damit, eine große Anzahl von möglichen Konfigurationen zu analysieren. Die zentrale Annahme der Methode ist, dass die einzelnen Teile des Systems (starrer Körper) während der gesamten globalen Optimierung nicht ihre interne Konfiguration ändern. Daher ist diese Methode ein geeignetes Werkzeug, um Phänomene wie Adsorption zu studieren, in dem alle Teilsysteme - Oberfläche und einzelne Moleküle - ihre interne Struktur bewahren. Der Algorithmus ermöglicht das Auffinden der globalen Minima für die Starrkörper, die dann im nächsten Schritt vollständig optimiert („relaxiert“) werden, um Verformungen aufgrund der Entspannung der Oberfläche und des Adsorbats auszumachen.
The present work was concentrated on developing the Rigid Body Genetic Algorithm (RBGA), and applying it to investigate the hydrocarbon adsorption on the MgO(001) surface. The RBGA method is a modified hybrid genetic algorithm with rigid body optimization at the local optimization step. The modification allows for a vast simplification of the optimization problem, and, in turn, to search a large number of possible configuration. The key assumption of the method is that individual parts of the system (rigid bodies) do not change their internal configuration throughout the global optimization. Therefore, this method is a perfect tool to study phenomena like adsorption, where all the subsystems – surface and individual molecules – preserve their internal structure. The algorithm allows to obtain global minima, which then can be fully optimized and to account for deformations due to the relaxation of the surface and adsorbate molecules.

This dissertation presents an analysis of two aspects of the chromatographic separation process known as Simulated Moving Bed (SMB) chromatography. The first aspect is system design, and the second is improving computer simulations to generate heuristics for choosing operational modes. For the past 15-20 years, there has been a surge of interest in the use of Simulated Moving Bed systems for the chromatographic separation of chemicals¹. A wide variety of methods, nomenclatures, and conventions have been adopted over the years²⁻⁴, as teams from different backgrounds adopt and improve on the SMB technology. This work presents a unifying discussion of the two major design methods, Triangle Theory and Standing Wave Design, used in the SMB field. We provide the complete computer code required to execute both design methods. A sample problem is worked, which demonstrates the novelty and ease of use that such tools provide. Mathematica was chosen for the implementation of these design methods, because of its strong symbolic analysis capabilities, and simplicity of creating interfaces for new users. We present derivations of the classic Langmuir results in Mathematica, and proceed to extend those implementations. When analytic solutions are impossible, we use Mathematica's numerical methods. This work also develops a distributed computing tool known as ChromRunner which allows large numbers of detailed numerical simulations to be run simultaneously. The motivations and benefits of this approach are discussed alongside implementation details. We apply the distributed computing system to two separate SMB separations in order to optimize them, as well as determine heuristics governing their operational modes. We wrote ChromRunner in C#, and took advantage of Visual Studio's Entity Framework to create the database backend. The user interface for this software was created using Microsoft's "Windows Presentation Foundation" (WPF) technologies.
Ph. D.

This dissertation describes the simulation and optimization of adsorptive and chromatographic separation processes. The first part focus on the simulation and comparison of operational modes in simulated moving bed (SMB) chromatography for separation and purification in bioprocesses. The second part includes the simulation of gas-phase adsorptive processes by pressure swing adsorption and temperature swing adsorption technologies. The applications of SMB chromatography are popular in separating and purifying enantiomers, petrochemicals, pharmaceuticals and biochemicals with higher yield and lower solvent consumption. We simulate and compare several operational modes of simulated moving bed (SMB) for a binary and a ternary bioprocess using Aspen Chromatography. These operational modes are able to improve the separation efficiency of the basic SMB process by our simulation and optimization. We compare their separation performances and identify heuristics that will guide the selection of operational modes across a variety of systems. Pressure swing adsorption (PSA) and temperature swing adsorption (TSA) are two of the main technologies for gas-phase adsorption separation processes. We simulate and demonstrate a PSA model for air separation system and a TSA model for CO2 capture system in Aspen Adsorption. We present their separation performance plots to provide the physical insights of these two systems.
Ph. D.

Un’aria salubre è un requisito essenziale, insieme a cibo e acqua. Nonostante gli ultimi due siano stati maggiormente percepiti come prioritari da molte civiltà per diversi secoli, l’aria è un qualcosa di imposto, senza possibilità di scelta. Sin dalla rivoluzione industriale, quando la popolazione iniziò a spendere buona parte del tempo in ambienti confinati, l’aria indoor avrebbe meritato maggiore considerazione, poiché risulta quella a cui essere maggiormente esposti. Gli inquinanti più comuni possono essere classificati in base alla loro natura: particolata o gassosa. Le strategie convenzionali per rimuoverli sono: rimozione della sorgente, diluzione tramite ventilazione e purificazione dell’aria. Mentre le emissioni indoor sono diffuse e non è sempre possibile isolarle e per ottemperare alle direttive di efficienza energetica, le strategie attive di rimozione degli inquinanti risultano essere preferibili. Le tecnologie per il trattamento dell’aria indoor vengono classificate in base al tipo di inquinante rimosso: filtri, precipitatori elettrostatici, separatori inerziali e scrubbers vengono generalmente utilizzati per la rimozione di particolato, mentre materiali adsorbenti, (foto)catalizzatori e reattori con lo sviluppo di plasma vengono utilizzati per la rimozione di gas. In questo studio è stata accuratamente valutata l’applicazione in loco e simultanea di tre diversi processi (adsorbimento, fotocatalisi e precipitazione elettrostatica) per la rimozione aumentata di inquinanti indoor. Per evidenziare le singole sinergie emergenti, e le interazioni tra processi e materiali, sono stati studiati prima i singoli processi accoppiati e, successivamente, l’innovativo processo ibrido risultante dalla loro azione combinata.
Clean air is an essential requirement of life, together with food and water. Although the latter two have been a primary concern for many civilizations for multiple centuries, air is something imposed, with no possibility of choice. Since the industrial revolution, as people started to spend most of their time in confined environments, clean air should have been considered a prerogative, as indoor air had become a leading exposure for humans. The most common indoor pollutants can be classified by their form: particulate or gaseous. Conventional strategies to combat the formers are source removal, dilution through ventilation and air treatment. While indoor emissions are ubiquitous and it is not always possible to remove the source, dilution through mechanical and natural ventilation and air cleaners are the generally preferred. As sustainability and energy-efficiency are becoming prerogatives in many countries, ventilation may imply energy losses, and therefore it can not be the only applicable strategy. For these reasons, air cleaners constitute a solution for removing harmful indoor pollutants. Indoor air treatment technologies are classified according to the type of pollutant removed: filters, electrostatic precipitators, inertial collectors, scrubbers are generally used for the removal of particles, while adsorptive media, (photo)catalysts, and plasma-operated reactors are adopted for the removal of gases. In this study, a simultaneous and in situ combination of the three previously reported methods (adsorption, photocatalysis and electrostatic precipitation) was deeply studied for the enhanced removal of indoor pollutants. The synergistic effect between each coupled process was investigated, in order to highlight the novelty of operating photocatalysis, adsorption and electrostatic precipitation in the single hybrid reactor.

The adsorption of dyes on activated carbon has been extensively studied in the past three decades. However, much due to the difficult to implement numerical procedures, these studies have been carried out without the necessary statistical background to make reliable conclusions. The main objective of this work was to perform the early stages of modeling and parameter estimation applied to the process of dyes adsorption on activated carbon, collaborating to the systematization of a computer routines set for the study of such process. The methodology has focused especially on the evaluation of the experimental error influence and linearization of the equilibrium models influence in the values of parameters and its confidence regions. The main routines used are part of a package called ESTIMA (PEQ/COPPE/UFRJ) which uses, basically, a stochastic method (Particle Swarm) together with a Gauss-Newton method in order to minimize the objective function. The parametric uncertainties have been compared by the elliptical approximation, the evaluation of several points obtained during minimization procedure, which are smaller than a determined limit, and an adapted method (SBA) from the Bootstrap method to build the parameters confidence region. Also, a methodology for model discrimination has been used and the effects of model linearization and proper characterization of experimental error have been studied. The realization of several replicates and subsequent error characterization have been shown of extremely importance to the study as the search for an alternative to obtain a more accurate estimate of the error in experimental conditions that have not been performed yet. It has been possible to experimentally show that the error on the amount adsorbed is indeed dependent of the error in the equilibrium concentration of adsorbate solution, a fact that, despite being known a priori, had not been yet demonstrated in other works. The comparison between linear and nonlinear methods also demonstrated how the linearization process negatively influences the correct data analysis and parameter determination. Through de analysis of the probabilities distribution of the equilibrium concentrations of the adsorbate solution (Ce), it has been shown that confidence region methods present a better performance when the dependent variable is transformed to the Log-Normal distribution, using the operation Neperian logarithm of Ce.
A adsorção de corantes têm sido extensivamente estudada nas três décadas passadas. Entretanto, muito devido à dificuldade de se implementarem procedimentos numéricos, estes estudos têm sido realizados sem o respaldo estatístico necessário. O objetivo principal desse estudo foi aplicar técnicas avançadas para o planejamento de experimentos e estimação de parâmetros direcionadas para o estudo de adsorção. Como objetivos específicos, pretende-se demonstrar os efeitos causados na qualidade dos parâmetros obtidos e na avaliação da incerteza desses parâmetros, através da região de confiança dos parâmetros quando comparado com técnicas normalmente utilizadas e contribuir, através dos resultados, para desenvolvimento de ferramentas computacionais para o estudo da adsorção de corantes em sólidos. As principais rotinas utilizadas fazem parte do pacote Estima (PEQ/COPPE/UFRJ) que utiliza um método estocástico (Enxame de Partículas) combinado com um método de otimização do tipo Gauss-Newton para a minimização da função objetivo na estimação dos parâmetros. Foram comparadas as incertezas paramétricas obtidas pela aproximação elíptica, por avaliação de diversos pontos obtidos durante a minimização que possuem valor da função objetivo menor ou igual a um certo limite de corte e um método adaptado (SBA) a partir do método do Bootstrap para construção da região de confiança dos parâmetros. Ainda, foi utilizada uma metodologia para discriminação de modelos e estudado os efeitos da linearização de modelos de isotermas de equilíbrio e da correta caracterização do erro experimental. A realização de várias réplicas e a consequente caracterização do erro experimental mostraram-se de extrema importância para o estudo bem como buscar alternativas para obter uma estimativa do erro experimental em condições onde ainda não foi realizado experimento. Foi possível comprovar experimentalmente que os erros na variável quantidade adsorvida realmente não são independentes dos erros na variável concentração de adsorbato no equilíbrio, fato que apesar de conhecido com antecedência até então não foi encontrado na literatura. A comparação entre os modelos lineares e não lineares também demonstrou como o processo de linearização influencia negativamente a correta análise dos dados e a determinação dos parâmetros. Através da análise da distribuição de probabilidades das concentrações de equilíbrio (Ce), foi mostrado que os métodos para construção da região de confiança apresentam melhor desempenho quando a variável dependente é transformada para a distribuição Log-Normal, fazendo a operação logaritmo neperiano de Ce.

Mestrado em Biotecnologia Industrial e Ambiental
Os fármacos estão entre os contaminantes aquáticos mais persistentes, resistindo aos processos convencionais aplicados nas estações de tratamento de águas residuais (ETAR) e, muitos deles, representam uma ameaça séria para organismos não-alvo e para o meio ambiente. Neste contexto, a adsorção a carvões ativados (CA) é uma das mais promissoras metodologias para a remoção de fármacos da água dada a sua versatilidade e alta eficiência de remoção. Contudo, os CAs implicam custos elevados. A lama primária da resultante do tratamento de efluentes da indústria papeleira foi anteriormente apresentada como uma potencial fonte de carbono alternativa e barata para a produção de CA por pirólise. A química computacional pode ser uma ferramenta valiosa na elucidação de alguns aspetos do mecanismo molecular de adsorção de poluentes orgânicos a CAs. No presente trabalho , é proposta a utilização de lama primária da indústria papeleira para a produção carvões (não)ativados. Os diferentes materiais foram caracterizados por um conjunto de técnicas experimentais, e os dados adquiridos usados na formulação de um modelo computacional válido, na tentativa de reproduzir a variabilidade do CA em termos de composição elementar, grupos funcionais e porosidade. O modelo desenvolvido foi usado na obtenção de informação pertinente através de técnicas de denâmica molecular/Monte Carlo que possibilite o melhoramento do CA inicial. Os resultados adquiridos em simulaçõesMonte Carlo sugerem que CAs com teores de oxigénio superiores apresentam valores de área superficial mais elevados, e, consequentemente, capacidades máximas de adsorção superiores. A presença de iões positivos no meio de adsorção apresenta-se como um fator cooperativo para a adsorção de SMX, dada a formação de complexos CA-Na+-SMX em dupla camada e estabilização de conformações abertas, tal como demonstrado através de simulações de dinâmica molecular.
Pharmaceutically active ingredients are amongst the most persistent wastewater contaminants, resisting to wastewater treatment plants (WWTP) conventional processes, and some of them are proved to pose serious threats to organisms and the environment. In this contect, adsorption by activated carbons (AC)is one of the most promising methodologies for the removal of pharmaceuticals from water due to its versatility and high removal efficiency. However, ACs are expensive and therefore now widely applied. Primary sludge from paper mills has been previously appointed as a potential cheap and renewable source of carbon for activated carbon production by pyrolysis. Computational chemistry may help shed some light unto the molecular mechanisms underlying the adsorption of organic pollutants in ACs. In this work, it is proposed the usage of primary paper mill sludge in the production of (non)activated carbons. The different materials were characterized by a set of techniques and the gathered data was used in the formulation of a validated model in an attempt to reproduce the elemental composition, functional group variability and porosity. The developed model was used in order to collect relevant information through molecular dynamics/Monte Carlo techniques, enabling the improvement of the initial AC material. The obtained data in Monte Carlo simulations suggest that AC with higher oxygen levels present greater values of surface are, and consequently superior maximum capacity values. The presence of positive ions in the adsorption medium presents itself as a cooperative factor for SMX adsorption, guven the formation of CA-Na+-SMX complexes and the estabilization of open configurations, such as demonstrated in molecular dynamics simulations.

Crystallization is a key unit operation used for obtaining purified products by many process industries. The key properties of the crystalline products, such as size and shape distribution, purity and polymorphic form are controlled by the crystallization process. All these properties impact significantly the downstream operations such as drying or filtration. Therefore, monitoring and controlling this process is fundamental to ensure the quality of the final product. Process analytical technology (PAT) brings numerous new methods and opportunities in the process analytics and real time process monitoring systems, which can be integrated into the control algorithm and provide high level optimal control strategies as well as deeper understanding of the process. Process monitoring helps develop mathematical models which can, in one hand, help in better understanding the processes and consecvently the development and application of advanced control methods in order to achieve better product quality. In this work, image processing and image analysis based direct nucleation control (IA-DNC) is developed in order to investigate the evolution of the crystal properties, such as crystal size, and crystal shape distribution. The IA-DNC approach is also compared to alternative DNC techniques, in which particle number were measured by Focused Beam Reflectance Measurement (FBRM) in order to control crystal size. A control approach is introduced that control the nucleation and disappearance of crystals during cooling and heating segments related to the changes of the number of counts (measured by Particle Vision Measurment, so called PVM or combination of FBRM and PVM). The approach was applied to investigate crystallization of compounds with different behavior: potassium dihydrogen phosphate (KDP) water, contaminated KDP -water and Ascorbic acid water systems. The results demonstrate the application of imaging technique for model-free feedback control for tailoring crystal product properties. The second main aim of the thesis is to investigate and control crystallization processes in impure media in the presence of multiple impurities, with an impact on the crystal shape via growth kinetics. The broad impact of the crystal growth modifiers (impurities) on the growth kinetics is observed in real time by using in situ video imaging probe and real-time image analysis. A morphological population balance model is developed, which incorporates a multi-site, competitive adsorption mechanism of the impurities on the crystal faces. The kinetic parameters of primary nucleation, growth and impurity adsorption for a model system of potassium dihydrogen phosphate crystallization in water in the presence of two impurities, were estimated and validated with experimental results. It was demonstrated that the model can be used to describe the dynamic evolution of crystal properties, such as size and aspect ratio during crystallization for different impurity profiles in the system. Manual, feedback and hybrid feedback-feedforward control techniques are developed and investigated numerically for continuous processes, while model-based and model-free control approach for crystal shape are developed for batch processes. The developed morphological population balance model is implemented and applied in the model-based control approaches, which are suitable to describe multicomponent adsorption processes and their influence on the crystal shape. Case studies show the effectiveness of crystal growth modifiers based shape control techniques. Comparison of different control approaches shows the effectiveness of the techniques. The third part of the thesis deals with purification of crystals when adsorption of impurities on crystal surfaces and its incorporation into crystals are considered. A purification method, called competitive purity control (CPC) is proposed and investigated. A morphological population balance model, including nucleation, growth and competitive impurity adsorption kinetics is developed to describe the case when multiple impurities can adsorb competitively on the crystal surface. The model is also combined with liquid phase chemical reaction model, in order to investigate the purity control case when an additive is introduced in the system that reacts with the impurity forming a non-adsorbing reaction product. Both competitive purity control approaches proposed: the adsorption based competitive purity control (A-CPC) and the reaction based competitive purity control (R-CPC); are investigated using detailed numerical simulations then compared with the alternative widely used purification method, called recrystallization. In the last contribution chapter, an integrated process optimization of a continuous chemical reactor and crystallizer is performed and studied numerically. The purpose of this study is to show the way in which the byproduct produced in the chemical reactor may affect the crystallization process and how its negative effect can be reduced by applying integrated process optimization. Sensitivity analysis of the system was performed by considering the flow rate and the concentration of substances in the input stream of the chemical reactor as manipulated process variables. Model based integrated process optimization and the sensitivity analysis in order to obtain improved quality product in terms of crystal size, shape and purity.

Myosin II is the molecular motor responsible for muscle contraction. It transforms the chemical energy in ATP into mechanical work while interacting with actin filaments in so called cross-bridge cycles. Myosin II or its proteolytic fragments e.g., heavy meromyosin (HMM) can be adsorbed to moderately hydrophobic surfaces in vitro, while maintaining their ability to translocate actin filaments. This enables observation of myosin-induced actin filament sliding in a microscope. This “in vitro motility assay” (IVMA) is readily used in fundamental studies of actomyosin, including studies of muscle contraction. The degree of correlation of the myosin II function in the IVMA with its function in muscle depends on how the myosin molecules are arranged on the surface. Therefore a multi-technique approach, including total internal reflection spectroscopy, fluorescence interference contrast microscopy and quartz crystal microbalance with dissipation, was applied to characterize the HMM surface configurations. Several configurations with varying distributions were identified depending on the surface property. The most favorable HMM configurations for actin binding were observed on moderately hydrophobic surfaces.   The effects on actomyosin function of different cargo sizes and amount of cargo loaded on an actin filament were also investigated. No difference in sliding velocities could be observed, independent of cargo size indicating that diffusional processive runs of myosin II along an actin filament are not crucial for actomyosin function in muscle. Furthermore, a tool for accurate velocity measurements appropriate for IVMAs at low [MgATP] was developed by utilizing the actin filament capping protein CapZ. These improvements allowed an investigation of the [MgATP]-velocity relationship to study possible processivity in fast skeletal muscle myosin II.  It is shown that the [MgATP]–velocity relationship is well described by a Michaelis-Menten hyperbola.  In addition, statistical cross-bridge modeling showed that the experimental results are in good agreement with recent findings of actomyosin cross-bridge properties, e.g., non-linear cross-bridge elasticity. However, no effect of inter-head cooperativity could be observed.   In conclusion, the described results have contributed to in-depth understanding of the actomyosin cross-bridge cycle in muscle contraction.

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.

A systematic study of trends in band gap and lattice energies for bare zinc oxide nanoparticles were performed by means of quantum chemical density functional theory (DFT) calculations and density of states (DOS) calculations. The geometry of the optimized structures and the appearance of their frontier orbitals were also studied. The particles studied varied in sizes from (ZnO)₆ up to (ZnO)₁₉₂.The functionalization of bare and hydroxylated ZnO surfaces with MPTMS was studied with emphasis on the adsorption energies for adsorption to different surfaces and the effects on the band gap for such adsorptions.

Research was performed at a pilot-scale wastewater treatment plant operating an adsorption/bio-oxidation (A/B) process at 20C. The study compared B-Stage performance under DO Control, Ammonia Based Aeration Control (ABAC), and Ammonia vs. NOx (AvN) control. AvN in 1) fully-intermittent and 2) intermittently-aerated MLE configurations was compared to DO Control and ABAC, each with continuous aeration, in an MLE configuration. The study also examined operation of each aeration strategy with two different feed types: A-Stage effluent (ASE) and primary clarifier effluent (PCE). Operating modes were compared on the basis of nitrogen removal performance, COD utilization efficiency for denitrification, and alkalinity consumption. AvN was found to provide comparable nitrogen removal performance to DO Control and ABAC. The highest nitrogen removal performance was seen when operating DO Control (81.4 ± 1.2%) and ABAC (81.1 ± 1.2%) with PCE. High nitrogen removal efficiency (77.5 ± 6.1%) was seen when fully-intermittent AvN operation was fed ASE containing a high particulate COD fraction. A high effluent nitrite accumulation ratio (NAR = NO2-/(NO2-+NO3-)) was seen during this period (46 ± 15%) accompanied by the out-selection of Nitrospira. Feeding effluent from AvN control to an Anammox MBBR improved removal efficiency. Increased soluble COD loading resulted in greater nitrogen removal with strategies operating in an MLE configuration while particulate COD was found to be important for processes where removal was designed to occur in downstream reactors. Efficiency of COD for denitrification was found to vary based on the amount and type of influent COD; however AvN in an MLE configuration was found to use COD more efficiently than fully-intermittent AvN. In either configuration, AvN required less alkalinity addition than DO Control or ABAC. High sCOD concentrations in PCE led to increased nutrient removal as compared to ASE but increased heterotrophic growth and mixed liquor concentrations in the B-Stage making the A-Stage an attractive option for its ability to control the C/N ratio fed to BNR processes.
Master of Science

Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009.
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.

L’objectif est de rechercher les moyens de valorisation de rejets talqueux ou de mélange de talc et de chlorite contenant de la dolomite ou du quartz. L’hydrophobicité naturelle du talc permet d'obtenir par flottation des concentrés enrichis en talc. Les résidus de cette opération contenant du talc, de la chlorite, de la dolomite, et du quartz sont commercialisable si l'on est capable d'éliminer les carbonates et le quartz. Cette séparation a été étudiée sur des phases pures en tube Hallimond et en micro cellule EMDEE. La mesure des temps d'induction et les résultats sur phases pures ont permis de définir les conditions optimales de flottation. Des essais en cellule de laboratoire ont confirmé les conclusions obtenues. Une étude plus fondamentale des phénomènes mis en jeu a été effectuée à partir de propriétés superficielles des phases pures et par l'étude de l'adsorption des différents réactifs

Os principais constituintes do ar, nitrogênio, oxigênio e argônio, estão cada vez mais presentes nas indústrias, onde são empregados nos processos químicos, para o transporte de alimentos e processamento de resíduos. As duas principais tecnologias para a separação dos componentes do ar são a adsorção e a destilação criogênica. Entretanto, para ambos os processos é necessário que os contaminantes do ar, como o gás carbônico, o vapor dágua e hidrocarbonetos, sejam removidos para evitar problemas operacionais e de segurança. Desta forma, o presente trabalho trata do estudo do processo de pré-purificação de ar utilizando adsorção. Neste sistema a corrente de ar flui alternadamente entre dois leitos adsorvedores para produzir ar purificado continuamente. Mais especificamente, o foco da dissertação corresponde à investigação do comportamento de unidades de pré-purificação tipo PSA (pressure swing adsorption), onde a etapa de dessorção é realizada pela redução da pressão. A análise da unidade de pré-purificação parte da modelagem dos leitos de adsorção através de um sistema de equações diferenciais parciais de balanço de massa na corrente gasosa e no leito. Neste modelo, a relação de equilíbrio relativa à adsorção é descrita pela isoterma de Dubinin-Astakhov estendida para misturas multicomponentes. Para a simulação do modelo, as derivadas espaciais são discretizadas via diferenças finitas e o sistema de equações diferenciais ordinárias resultante é resolvido por um solver apropriado (método das linhas). Para a simulação da unidade em operação, este modelo é acoplado a um algoritmo de convergência relativo às quatro etapas do ciclo de operação: adsorção, despressurização, purga e dessorção. O algoritmo em questão deve garantir que as condições finais da última etapa são equivalentes às condições iniciais da primeira etapa (estado estacionário cíclico). Desta forma, a simulação foi implementada na forma de um código computacional baseado no ambiente de programação Scilab (Scilab 5.3.0, 2010), que é um programa de distribuição gratuita. Os algoritmos de simulação de cada etapa individual e do ciclo completo são finalmente utilizados para analisar o comportamento da unidade de pré-purificação, verificando como o seu desempenho é afetado por alterações nas variáveis de projeto ou operacionais. Por exemplo, foi investigado o sistema de carregamento do leito que mostrou que a configuração ideal do leito é de 50% de alumina seguido de 50% de zeólita. Variáveis do processo foram também analisadas, a pressão de adsorção, a vazão de alimentação e o tempo do ciclo de adsorção, mostrando que o aumento da vazão de alimentação leva a perda da especificação que pode ser retomada reduzindo-se o tempo do ciclo de adsorção. Mostrou-se também que uma pressão de adsorção maior leva a uma maior remoção de contaminantes.
The main constituents of air, nitrogen, oxygen and argon, are increasingly present in industries where they are employed in chemical processes, to transport food and waste processing. The two main technologies for the separation of air components are the adsorption and cryogenic distillation. However, for both processes is necessary to remove air contaminants, such as carbon dioxide, water vapor and hydrocarbons, to avoid operational problems and safety concerns. Thus, this work deals with the study of air pre-purification using adsorption. In this system the air current flows alternately between two adsorbing beds to produce clean air continuously. More specifically, the focus of the dissertation is to investigate the behavior of pre-purification units, PSA (pressure swing adsorption), where the desorption step is accomplished by reducing the pressure. The analysis of pre-purification unit begins with adsorption beds modeling through a partial differential equations system of mass balance in the gas stream and in the bed. In this model, the adsorption equilibrium is described by the Dubinin-Astakhov isotherm extended to multicomponent mixtures. For the simulation model, the spatial derivatives are discretized via finite differences and the ordinary differential equations system resultant is solved by an appropriate solver (method of lines). To the operating unit simulation, this model is coupled to a convergence algorithm on the four phases of the operation: adsorption, depressurization, purge and desorption. The algorithm in question must ensure that the final terms of the final stage are equivalent to the initial conditions of the first stage (cyclic steady state). Thus, the simulation was implemented in the form of a computational code based programming environment Scilab (Scilab 5.3.0, 2010), which is a program of free distribution. The simulation algorithms of each individual step and the complete cycle are finally used to analyze the behavior of pre-purification unit, checking how their performance is affected by changes in design variables or operational. For example, we have investigated the charging system of the bed and showed that the optimal configuration of the bed is 50% alumina followed by 50% of zeolite. Process variables were also examined, the adsorption pressure, the flow rate and cycle time of adsorption, showing that increasing the feed flow rate leads to a loss of specification that can be taken up by reducing the cycle time of adsorption. It was also shown that a higher pressure adsorption leads to a greater removal of contaminants.

Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro
As técnicas inversas têm sido usadas na determinação de parâmetros importantes envolvidos na concepção e desempenho de muitos processos industriais. A aplicação de métodos estocásticos tem aumentado nos últimos anos, demonstrando seu potencial no estudo e análise dos diferentes sistemas em aplicações de engenharia. As rotinas estocásticas são capazes de otimizar a solução em uma ampla gama de variáveis do domínio, sendo possível a determinação dos parâmetros de interesse simultaneamente. Neste trabalho foram adotados os métodos estocásticos Luus-Jaakola (LJ) e Random Restricted Window (R2W) na obtenção dos ótimos dos parâmetros cinéticos de adsorção no sistema de cromatografia em batelada, tendo por objetivo verificar qual método forneceria o melhor ajuste entre os resultados obtidos nas simulações computacionais e os dados experimentais. Este modelo foi resolvido empregando o método de Runge- Kutta de 4 ordem para a solução de equações diferenciais ordinárias.
The inverse techniques have been used in the determination of parameters involved in design and performance of many industrial processes. The application of stochastic methods has increased in recent years, demonstrating their potential in study and analysis of different systems in engineering applications. Stochastic routines are able to optimize the solution in a wide range of variables, it is possible to determine the parameters of interest simultaneously. In this work two adopted the stochastic methods, Luus-Jaakola (LJ) and Restricted Random Window (R2W), to obtain the optimum parameters for adsorption kinetics in batch chromatography system, aiming to determine which method would provide the best fit between the results obtained in computer simulations and experimental data. This model was solved using the Runge-Kutta 4th order for ordinary differential equations solution.

La durabilité des matériaux est leur capacité à résister dans le temps à l'influence de divers facteurs tels que la température, l'humidité, la rupture, tout en conservant leurs caractéristiques.Les matériaux polymères durables sont la solution contre la pollution de l'environnement. Dans ce contexte, le développement de matériaux polymères durables basés sur des composés biodégradables, que l'on trouve en abondance dans la nature, même à partir de déchets industriels, et qui ont également un faible prix de revient, est une alternative possible aux matériaux basés sur des composés fossiles, qui sont toxiques. En même temps, l'utilisation d'un minimum de produits chimiques est un atout pour la production à grande échelle par les industries. En outre, l'obtention de propriétés avantageuses dans ces conditions, adaptées à certains types d'applications, ajoute de la valeur, ce qui recommande leur utilisation par rapport aux matériaux toxiques.Les oligo- et polysaccharides constituent une matière première appropriée qui pourrait être exploitée dans la conception de matériaux polymères durables. Leur utilisation a déjà suscité un réel intérêt de la part des chercheurs, mais leur application au niveau industriel se heurte à un certain nombre de difficultés : des procédés technologiques inadaptés et de la consommation élevée de solvants et de produits chimiques au coût élevé de l'obtention, du recyclage et de la réutilisation des matériaux, conformément à une économie circulaire, essentielle dans l'approche de la protection de l'environnement. Cette économie circulaire consiste à prolonger le cycle de vie des matériaux en réduisant les déchets. Elle privilégie la réparation, la réutilisation et le recyclage des matériaux le plus longtemps possible. Cette thèse de doctorat présente les résultats obtenus par la synthèse, la caractérisation et le test de matériaux durables à base d'oligo- et de polysaccharides.L'objectif global de la thèse de doctorat est de développer des matériaux durables qui intègrent et exploitent des composés non toxiques, renouvelables, respectueux de l'environnement, bon marché et abondants dans la nature tels que les oligo- et polysaccharides dans une économie circulaire.Les principaux axes de recherche développés dans la thèse sont:- Valorisation de la β-cyclodextrine, de la catégorie des oligosaccharides, et du chitosane, de la catégorie des polysaccharides, dans des systèmes de matériaux durables;- Développement de tels matériaux durables, en utilisant également un minimum d'étapes et un nombre réduit de composés et de solvants respectueux de l'environnement;- Utilisation, en particulier, du chitosane sous forme solide (poudre) pour optimiser les propriétés mécaniques et thermiques des systèmes;- Obtention de propriétés matérielles améliorées par l'introduction d'oligo- et de polysaccharides, par rapport aux systèmes de référence, pour les systèmes à base de chitosane: amélioration des caractéristiques mécaniques et thermiques, et pour les systèmes à base de β-cyclodextrine: optimisation de l'adsorption de divers polluants tels que les antibiotiques, les colorants organiques, les métaux lourds;- Augmenter le potentiel d'application des matériaux dans divers domaines tels que le biomédical, l'emballage alimentaire, les revêtements époxy, l'aérospatiale, en raison des avantages que possèdent les oligo- et les polysaccharides ;- Vérifier la recyclabilité des nanomatériaux à base de β-cyclodextrine afin d'améliorer la durabilité des matériaux
The durability of materials is their ability to withstand over time the influence of various factors such as temperature, humidity and breakage while maintaining their characteristics.Durable polymer materials are the solution to environmental pollution. In this context, the development of sustainable polymer materials based on biodegradable compounds, which are abundant in nature, even from industrial waste, and which also have a low cost price, is a possible alternative to materials based on fossil compounds, which are toxic. At the same time, the use of minimal chemicals is an advantage for large-scale production by industries. In addition, obtaining advantageous properties under these conditions, tailored to certain types of applications, brings added value, which recommends their use over toxic materials.Oligo- and polysaccharides represent a suitable raw material that could be exploited in the design of durable polymeric materials. Their use has already aroused real interest among researchers, but their industrial application faces a number of difficulties: from inadequate technological processes and high consumption of solvents and chemicals to the high costs of obtaining, recycling and reusing materials, in line with a circular economy, which is essential in addressing environmental protection. This circular economy is about extending the life cycle of materials by reducing waste. by promoting the repair, reuse and recycling of materials for as long as possible. This PhD thesis presents the results obtained from the synthesis, characterisation and testing of sustainable oligo- and polysaccharide-based materials.The overall objective of the PhD thesis is to develop durable materials that incorporate and exploit non-toxic, renewable, environmentally friendly, cheap and naturally abundant compounds such as oligo- and polysaccharides in a circular economy.The main research directions developed in the thesis are:- Valorisation of β-cyclodextrin, from the oligosaccharide category, and chitosan, from the polysaccharide category, in sustainable material systems;- Development of such sustainable materials using a minimum number of steps and a reduced number of compounds and solvents;- The use, in particular, of chitosan in solid (powder) form to optimise the mechanical and thermal properties of the systems;- Achieving improved mechanical and thermal properties of the materials by introducing oligo- and polysaccharides, compared to reference systems, for chitosan-based systems, and for β-cyclodextrin-based systems: optimised adsorption of various pollutants such as antibiotics, organic dyes, heavy metals;- increased application potential of materials in various fields such as biomedical, food packaging, epoxy coatings, aerospace, due to the advantages of oligo- and polysaccharides;- Testing the recyclability of β-cyclodextrin-based nanomaterials to improve material durability

Doutoramento em Engenharia Química
A exploração de compostos, subprodutos e resíduos naturais é um passo chave para a obtenção de um futuro sustentável. A valorização e comercialização destes materiais dependem da aplicação de técnicas adequadas de conversão e separação/purificação que permitam obter os níveis desejados de pureza e produtividade. Os ácidos triterpénicos, particularmente os ácidos betulínico, oleanólico e ursólico, são compostos de elevado valor que têm atraído interesse devido às suas já reportadas propriedades nutraceuticas e farmacológicas. Estes triterpenoides estão presentes em diversas fontes vegetais mas podem ser encontrados com abundâncias consideráveis na casca do eucalipto (decídua e externa), um resíduo comum da indústria da pasta e papel. O isolamento dos ácidos triterpénicos é uma tarefa difícil devido às suas semelhantes estruturas moleculares, especialmente no caso dos ácidos oleanólico e ursólico, que são isómeros de posição. O leito móvel simulado (simulated moving bed, SMB) é uma técnica cromatográfica de separação contínua e em contracorrente que maximiza a força diretriz de transferência de massa permitindo a separação de moléculas mesmo quando as seletividades se aproximam de um. Por exemplo, é frequentemente utilizada no isolamento de enantiómeros. No SMB clássico a separação de dois componentes é efetuada em quatro zonas, os caudais e concentrações de alimentação são fixos e as portas de entrada/saída são comutadas simultaneamente. Recentemente, novas implementações tais como a modificação da concentração ou caudais da alimentação, a utilização de tempos de comutação variáveis e a introdução de novas zonas para separação multicomponente, têm permitido a obtenção de maior flexibilidade e melhor performance. Uma revisão profunda destes modos de operação foi feita durante esta tese. A modelação e otimização são passos essenciais no dimensionamento e desenvolvimento de qualquer processo e particularmente importantes no SMB. Como ponto de partida para o estudo do fracionamento de ácidos triterpénicos por leito móvel simulado, modelos fenomenológicos conhecidos foram aplicados para desenvolver de um simulador SMB. Durante este trabalho uma estratégia de otimização de unidades de SMB foi desenvolvida combinando as metodologias de desenho de experiências e respostas de superfície com simulações computacionais, com o objetivo de obter condições de operação ótimas com baixa complexidade e um esforço computacional reduzido. Esta técnica de otimização foi aplicada ao estudo da separação dos enantiómeros de óxido de trans-estilbeno, usando informação da literatura, e posteriormente comparada com outros procedimentos de determinação de condições de operação ótimas. Esta técnica permitiu purezas acima de 99.5 % para ambos enantiómeros, necessitando de um baixo número de simulações. A separação de ácidos triterpénicos foi inicialmente estudada à escala analítica, através de uma série de ensaios cromatográficos em diferentes condições para seleção de fase móvel e estacionária apropriada. Os melhores resultados foram obtidos com uma coluna Apollo C18 usando metanol/água 95/5 (%,v/v) e os parâmetros de equilíbrio e transporte foram determinados através de experiências de rutura com os compostos puros. Esta informação foi utilizada com sucesso na simulação da separação de uma mistura ternária, cujos resultados foram validados com experiências de rutura ternárias. A separação em SMB de uma mistura representativa de um extrato natural contendo os ácidos betulínico, oleanólico e ursólico foi desenhada utilizando um processo em dois passos: inicialmente o ácido betulínico foi isolado dos ácidos oleanólico e ursólico e, de seguida, os ácidos oleanólico e ursólico foram fracionados. Esta separação foi otimizada usando a metodologia de desenho de experiências e respostas de superfície combinada com simulações rigorosas e permitiu demonstrar que é possível produzir os ácidos betulínico, oleanólico e ursólico com purezas de 99.4 %, 99.1 %, e 99.4 %. Os polímeros molecularmente impressos (molecularly imprinted polymers, MIPs) são sintetizados para possuírem centros ativos altamente seletivos para moléculas alvo, tornando-os adsorventes muito promissores. Vários MIPs foram sintetizados por polimerização por precipitação usando diferentes formulações. Após a preparação, estes polímeros foram caracterizados por microscopia eletrónica de varrimento e os mais promissores, em termos de características morfológicas, foram diretamente testados através de experiências de adsorção. Os resultados revelam que o material “MIP1b” exibe selectividade infinita para o ácido oleanólico, a molécula alvo usada na sua síntese. Em conjunto com a sua capacidade de adsorção – superior à da previamente estudada fase C18 – estes resultados demonstram o elevado potencial do polímero “MIP1b” para aplicação na separação dos ácidos triterpénicos. Investigação adicional é necessária neste tópico onde diferentes técnicas de separação podem ser antecipadas. Este trabalho culminou com o dimensionamento e montagem de uma unidade laboratorial de leito móvel verdadeiro baseada num sistema de uma-válvula-ST por coluna recentemente patenteado, que permite à unidade operar sobre diferentes estratégias de operação e configurações.
The exploitation of natural compounds, by-products and residues is a key strategy for the pursuit of a sustainable future. The effective valorization and commercialization of these materials depends on the application of adequate conversion and separation/purification techniques that can provide desired levels of purity and productivity. Triterpenic acids, particularly betulinic, oleanolic, and ursolic acids, are high value molecules that have attracted considerable interest due to their reported nutraceutical and pharmacological properties. These triterpenoids are present in diverse vegetable sources but significant abundances are found in Eucalyptus bark (deciduous and external), a common residue from the paper and pulp industry. The isolation of triterpenic acids is a difficult task due to their similar molecular structures, particularly in the case of oleanolic and ursolic acids, which are positional isomers. The simulated moving bed (SMB) technology is a countercurrent continuous chromatographic technique that maximizes the mass transfer driving force, thus allowing the separation of compounds even when selectivities approach one. For instance, it is often used for enantiomers isolation. In a classic SMB, the separation of two components is accomplished across four zones, the flow rates and feed concentrations are fixed, and the inlet/outlet ports are switched synchronously. Recently, new implementations and modifications, such as the modulation of feed concentration or flow rates, variable switch times and additional zones for multicomponent separations, enabled better flexibility and performances to be achieved. A thorough review of these modes of operation was performed in this thesis. Modeling and optimization are necessary steps for the design and development of any process, being particularly important in SMB. As the starting point for the study of the fractionation of triterpenic acids by simulated moving bed, well know phenomenological models were applied to develop a SMB simulator. During this work, an optimization strategy of SMB units was developed combining the design of experiments and response surface methodologies (DoE-RSM) with computer simulations, aimed at providing good operating conditions with low complexity and reduced computational effort. This optimization technique was applied to the separation of trans-stilbene oxide (TSO) enantiomers using data from the literature and compared with other existing procedures for the determination of the best operation conditions. It allowed purities above 99.5 % for both TSO enantiomers while requiring a small number of simulations. The separation of triterpenic acids was initially studied at analytical scale, through a series of chromatographic assays under different conditions, to select appropriate mobile and stationary phases. Best results were obtained using an Apollo C18 column and methanol/water 95/5 (%, v/v), and equilibrium and mass transport parameters were determined through breakthrough experiments with pure compounds. This information was then successfully applied in the simulation of a ternary mixture separation, whose results were validated with ternary breakthrough measurements. The SMB separation of a representative natural extract containing betulinic, oleanolic and ursolic acids was designed using a two-step process: firstly, betulinic acid was isolated from oleanolic and ursolic acids, and secondly, oleanolic and ursolic acids were fractionated. This separation approach was optimized using DoE-RSM combined with rigorous simulations, and it was demonstrated that it is possible to produce betulinic, oleanolic and ursolic acids with purities of at least 99.4 %, 99.1 %, and 99.4 %. Molecularly imprinted polymers (MIPs) are synthesized to possess binding sites highly selective to specific molecules, making them very promising adsorbents. Several MIPs were synthetized by precipitation polymerization using different formulations. After preparation, these polymers were characterized by scanning electron microscopy and the most successful ones, in terms of morphological features, were directly tested carrying out batch adsorption experiments. The results disclosed that “MIP1b” material exhibits infinite selectivity for oleanolic acid, the template molecule used in its synthesis. Together with its adsorption capacity – even higher than that of the previously studied C18 phase – these results demonstrate the high potential of “MIP1b” polymer for application on the separation of triterpenic acids. Additional research is required in this topic, where distinct separation approaches may be anticipated. This PhD work culminated in the design and assembling of a laboratory simulated moving bed unit based on a recently patented system using a one- ST valve per column valve scheme, thus allowing the SMB to run under several operation strategies and configurations.

Les techniques de la chromatographie en phase liquide ont permis de mettre au point une separation optimisee des impuretes de la cyclododecanone oxime. La methode la plus performante est la chromatographie de partage a polarite de phases inversee sur un gel de silice greffee octadecyle avec une phase mobile ayant la composition suivante : methanol-acetonitrile-tetrahydrofurane-eau 33:24:3,5:39,5 (v/v). Une trentaine d'impuretes sont ainsi mises en evidence grace a l'emploi d'une colonne de petit calibre de 1 metre de long et de 1 millimetre de diametre interieur. Cette colonne contient 30000 plateaux theoriques. La duree de la separation est de 3,5 heures. L'identification d'un certain nombre de ces impuretes a ete effectuee par la conjonction de differentes methodes : couplage en ligne avec la spectrometrie de masse et chromatographie semi-preparative permettant d'isoler des quantites notables de certaines impuretes identifiees par la spectrometrie de masse differee de meme on a pu appliquer a ces impuretes la spectrometrie infrarouge par transformee de fourier

Microfluidics is a continually growing field covering a wide range of applications, such as cellular analysis, biomarker quantification, and drug discovery; but in spite of this, the field of microfluidics remains predominately academic. New materials are pivotal in providing tailored properties to improve device integration and decrease prototype turnaround times. In biosensing, nonspecific adsorption in microfluidic systems can deplete target molecules in solution and prevent analytes, especially those at low concentrations, from reaching the detector. Polyethylene glycol diacrylate (PEGDA) mixed with photoinitiator forms, on exposure to ultraviolet (UV) radiation, a polymer with inherent resistance to nonspecific adsorption. Optimization of the polymerized PEGDA (poly-PEGDA) formula imbues this material with some of the same properties, including optical clarity, water stability, and low background fluorescence, that makes polydimethylsiloxane (PDMS) a widely used material for microfluidics. Poly-PEGDA demonstrates less nonspecific adsorption than PDMS over a range of concentrations of flowing fluorescently tagged bovine serum albumin solutions, and poly-PEGDA has greater resistance to permeation by small hydrophobic molecules than PDMS. Poly-PEGDA also exhibits long-term (hour scale) resistance to nonspecific adsorption compared to PDMS when exposed to a low (1 μg/mL) concentration of a model adsorptive protein. Electrophoretic separations of amino acids and proteins resulted in symmetrical peaks and theoretical plate counts as high as 4 × 105/m. Pneumatically actuated, non-elastomeric membrane valves fabricated from poly-PEGDA have been characterized for temporal response, valve closure, and long-term durability. A ∼100 ms valve opening time and a ∼20 ms closure time offer valve operation as fast as 8 Hz with potential for further improvement. Comparison of circular and rectangular valve geometries indicates that the surface area for membrane interaction in the valve region is important for valve performance. After initial fabrication, the fluid pressure required to open a closed circular valve is ∼50 kPa higher than the control pressure holding the valve closed. However, after ∼1000 actuations to reconfigure polymer chains and increase elasticity in the membrane, the fluid pressure required to open a valve becomes the same as the control pressure holding the valve closed. After these initial conditioning actuations, poly-PEGDA valves show considerable robustness with no change in effective operation after 115,000 actuations.Often, localized areas of surface functionalization are desired in biosensing, necessitating site-specific derivatization. Integration of poly-PEGDA with different substrates, such as glass, silicon, or electrode-patterned materials, allows for broad application in biosensing and microfluidic devices. Deposition of 3-(trimethoxysilyl) propyl methacrylate or (3-acryloxypropyl) dimethylmethoxysilane onto these substrates makes bonding to poly-PEGDA possible under UV exposure. Primary deposition of (3-acryloxypropyl) dimethylmethoxysilane, followed by photolithographic patterning, allows for silane removal through HF surface etching in the exposed areas and subsequent deposition of 3 aminopropyldiisopropylethoxysilane on the etched regions. Fluorescent probes are used to evaluate surface attachment methods. Primary attachment via reaction of Alexa Fluor 488 TFP ester to the patterned aminosilane demonstrates excellent fluorescent signal. Initial results with glutaraldehyde were demonstrated but require more optimization before this method for secondary attachment is viable. Fabrication of 3D printed microfluidic devices with integrated membrane-based valves is performed with a low-cost, commercially available stereolithographic 3D printer and a custom PEGDA resin formulation tailored for low non-specific protein adsorption. Horizontal microfluidic channels with designed rectangular cross sectional dimensions as small as 350 µm wide and 250 µm tall are printed with 100% yield, as are cylindrical vertical microfluidic channels with 350 µm designed (210 µm actual) diameters. Valves are fabricated with a membrane consisting of a single build layer. The fluid pressure required to open a closed valve is the same as the control pressure holding the valve closed. 3D printed valves are successfully demonstrated for up to 800 actuations. Poly-PEGDA is a versatile material for microfluidic applications ranging from electrophoretic separations, valve implementation, and heterogeneous material integration. Further improvements in PEGDA resin formulation, in combination with a UV source 3D printer, will provide poly-PEGDA devices that are not only rapidly fabricated (<40 min per device), but that also include pumps and valves and are usable with a variety of detection methods, such as laser-induced fluorescence and immunoassays, for broad application in biosensing.

This thesis presents work on a holistic approach for improving the overall design of solar cooling systems driven by solar thermal collectors. Newly developed methods for thermodynamic optimization of hydraulics and control were used to redesign an existing pilot plant. Measurements taken from the newly developed system show an 81% increase of the Solar Cooling Efficiency (SCEth) factor compared to the original pilot system. In addition to the improvements in system design, new efficiency factors for benchmarking solar cooling systems are presented. The Solar Supply Efficiency (SSEth) factor provides a means of quantifying the quality of solar thermal charging systems relative to the usable heat to drive the sorption process. The product of the SSEth with the already established COPth of the chiller, leads to the SCEth factor which, for the first time, provides a clear and concise benchmarking method for the overall design of solar cooling systems. Furthermore, the definition of a coefficient of performance, including irreversibilities from energy conversion (COPcon), enables a direct comparison of compression and sorption chiller technology. This new performance metric is applicable to all low-temperature heat-supply machines for direct comparison of different types or technologies. The achieved findings of this work led to an optimized generic design for solar cooling systems, which was successfully transferred to the market.

碩士
明志科技大學
生化工程研究所
96
In this study, the commercial STREAMLINE DEAE adsorbent was used to investigate the adsorption and desorption characteristics b-D-galactosidase (b-gal, EC 3.2.1.23) in the crude cell homogenate. In a series of batch and packed bed operations, the optimal adsorption and elution conditions for b-gal were obtained. These experiments included a series of operating parameters such as the choice of absorption pH, the effect of whole cells on the binding capacity, the experiments equibrium adsorption isotherm and uptake rate were also investigated. The effects of ionic strength, salt concentration, and linear velocity on the elution process were carried out in a small packed bed. The results were used to assess the feasibility of using stirred fluidized bed chromatography for direct recovery of b-gal from different operating conditions in highly crude cell homogenates. The recovery yield for b-gal was approximately 45.07% with a purification factor of 2.07 by using 0.5 M NaCl as an eluent at a linear velocity of 150 cm/h.

碩士
明志科技大學
生化工程研究所
96
The method development for direct capture of His-tag enhanced green fluorescent protein (His-EGFP) from unclarified E.coli homogenates using stirred fluidized bed (SFB) has been described. Cu(II), Zn(II), Ni(II) and Co(II) metal ion were evaluated in immobilized metal affinity chromatography (IMAC) for the recovery of His-EGFP. Immobilized Ni(II) chelating adsorbent was found to be the most effective for capture of His-EGFP. The adsorption characteristic of Ni(II)-STREAMLINE chelating adsorbent used in this work for total protein and His-EGFP in unclarified E.coli homogenates has been assessed by the measurements of equilibrium adsorption isotherm and uptake rate. Optimal conditions for the elution of His-EGFP were also investigated in packed bed experiments conducted with clarified E.coli homogenates. On the basis of the results, direct capture of His-EGFP from unclarified E.coli homogenates by SFB was carried out under the different loading volumes (50-200 ml). The purification results showed that the His-EGFP was directly recovered using 150 mM Imidazol buffer (pH 7) from unclarified E.coli homogenate with a purification factor of 2.04 and yield of 73.6% in the single step. Other contaminants were completely eluted by using 25 mM EDTA ( pH 7).

Conversion of biomass to useful bio-products is a lengthy and often inefficient process. Research has looked at the conversion of cellulose to ethanol by means of termite bacterial consortium in fluidized bed bioreactor, where the bacteria are attached as biofilm to an activated carbon or cellulose support. High conversion rates were achieved in this reactor and the process was fairly robust and flexible. However establishing the biofilm on the activated carbon was a lengthy process in terms of the time it took the bacteria to attach to the various substrates (Activated Carbon and Cellulose) and form flocculants. The formation of such flocculants substantially increases the reaction surface and hence should optimize the production of ethanol. Many physical, chemical, and biological interactions facilitate the attachment of bacteria to surfaces. It was in this study that the electrostatic attraction was investigated. The understanding of the physical modifications of surface charge was chosen to be investigated in order to understand the ideal conditions to propagate and increase biofilm creation. Bacteria carry a negative surface charge and hence for increased attraction, the surface charge of the substrate should be modified to be positive. This research, performed as batch processes, has shown that with the correct surface charge modifications of the substrate the electrostatic attraction forces between the surface and the bacteria are maximized. As a result of the strong electrostatic attraction forces between the two surfaces the bacteria adsorbs and attaches to the substrate quicker and creates a biofilm on the surface. Prior to the attachment investigation it was important to attempt to understand the bacteria consortium within the termite gut.. The “worker” termites collect the food and feed off the soil whilst building their mound.. The bacteria found within the termite are in line with cellulose degradation, which can be manipulated for biofuels production. This study aimed to investigate a series of procedures of charge manipulation to the surfaces of both the substrate and bacteria in order to see the influence of electrostatic interaction on biofilm creation. It was seen that when only the activated carbons surface charge was modified to have a positive net charge the attachment of bacteria was most prominent. In addition it was proven that after being charged to a pH of 5 (4.28 x 104 Bacteria/mm2 Activated Carbon), 6 (3.90 x 104 Optimization of Microbial Adsorption (Biofilm Creation) on Activated Carbon by Surface Modification of Substrate 2013 Bacteria/mm2 Activated Carbon) and 7 (1.58 x 105 Bacteria/mm2 Activated Carbon) were achieved. The greatest attachment was seen when the activated carbon was charged to a pH of 7. This can be explained as the optimal positive pH the activated carbon should be charged to if its pHPZC is 9.7. If the pH is dropped lower than 7 although the surface becomes more positive, the surface actually approaches the surface charge of bacteria and the electrostatic interaction dissipates. In an effort to use the optimal pH modification to create a biofilm on the surface of the activated carbon time experiments were performed. After 13 days biofilms on the surface of the activated carbon surfaces were seen. The bacteria attach to surface of the activated carbon and produce Extracellular Polymers Substance (EPS) fluid which then causes other bacteria to attach to them resulting in the formation of Biofilms.

碩士
明志科技大學
生化工程研究所
98
Pichia pastoris was genetically engineered to express beta-galactosidase (β-gal) for use in this study. To increase beta-gal production, the growth conditions in the shake flask culture and fermentor culture were investigated. Under the conditions employed, the OD600 value of the fermentor culture was approximately 45. The collected cells were disrupted by high pressure homogenizer for six cycles at 30 Kpsi and 4oC. The release of beta-gal and total protein from 25% (ww/v) disrupted cells were 2.02x103 U/ml and 17.2 mg/ml, respectively. The ion exchange adsorbent (i.e. STREAMLINE DEAE) was chosen and used to evaluate the adsorption efficiency for beta-gal at various pH values. The optimal adsorption pH for β-gal was found to be pH 6 and the binding capacity of the adsorbent was 5.6x106 U/ml. For one-factor-at-a-time experiments, the effects of loading flow rate, bed height, cell concentration, and residence time on 5% dynamic binding capacity (DBC) were investigated in packed beds. The optimization of 5% DBC for β-gal in packed beds was performed using both fractional factorial design (FFD) and response surface methodology (RSM). A second-order was proposed to represent the binding capacity for β-gal as a function of loading flow rate (F), cell concentration (Co), packed bed height (H). Under optimal conditions (F: 2.96 ml/min, Co: 45% (ww/v), H: 16.6 cm), the model predicted binding capacity for β-gal was 1.15x105 U/ml which approached to the average experimental value of 1.13x105 U/ml.

碩士
中原大學
化學研究所
102
In this thesis, the concept of isoreticular chemistry was used by extended the length of organic ligands in the synthesis of Metal-Organic frameworks (MOFs). The ligand used in this study is 4,4'-stilbene dicarboxylic acid (H2SDC).The optimization synthesis was achieved by using ammonium fluoride (NH4F), potassium fluoride (KF) as additives. The study MOFs were listed as: [Cr3F/OH(H2O)2O(SDC)3]……..(1) [Cr(OH)(SDC)]…………...........(2) On the structural identification, powder X-ray diffraction can identify the product phases; scanning electron microscopy (SEM) displays the crystal morphology and size; thermogravimetric analysis (TGA) measures sample weight loss under heating; gas adsorption displays the porous behaviors. All measurements confirmed the optimization synthesis in both MOFs. The final results display optimized addition of ammonium fluoride and potassium fluoride is about 0.06~0.10 mmole and result in higher specific surface area of MOF (1). In addition, the higher porosity can be observed in the addition of ammonium fluoride when compare to potassium fluoride.

碩士
逢甲大學
化學工程研究所
82
To emphasize the importance of the functions of thermal swing adsorption system in fixed beds on both air purification and solvent recovery, the system cyclic behavior includes not only the purification efficiency of the process air but also the enhancement ratio of the regeneration gas. For a specified adsorbate-adsorbent pair at a specified inlet temperature and concentration, the dimensionless parameters of the model affecting the system cyclic behavior include the dimensionless heat and mass transfer parameters and the dimensionless operating parameters, which are mainly functions of the transport properties and the operating conditions. In the study, the theoretical analysis was performed for a single component system to establish the relationship between the cyclic behavior and the dimensionless parameters, i.e. the so called dimensionless cyclic behavior chart in which the ordinate represents the cyclic behavior and the abscissa represents the operating cost. Each curve on the chart was formed at a specified purification efficiency and the lowest point of the curve can be taken as the optimal operating point of the system at this purification efficiency. Also, this optimal operating point was used as a criterion to select the optimal design and operating parameters in several case studies. Taking the acetone-activated carbon system as an example, the simulation results showed that the addition of a cooling step into the system can only improv1;the enhancement ratio of the regeneration gas a little and the enhancement ratio is about∼ 2.5 for the base point of the simulation , where the purification efficiency of the process air is set at 95%. The enhancement ratio of the system can be futher increased by decreasing the inlet concentration of the process air, increasing the inlet temperature of the regeneration gas, decreasing the purification efficiency of the process air, improving the mass transfer rates within the particles, and increasing the bed length.

碩士
中國文化大學
應用化學研究所
95
Most studies in this area focus on the alkali atom Si(001)-2×1 surface. Work on the alkali or alkaline earth clusters, has not been seen. We have used some small Si-H clusters to represent the nuit cells of a reconstructed ideal Si(111) surface. Adsoprtion of some Mg clusters will be reported here. We used the softwares and GAUSSIAN 03 package at the NCHC of structure imization on the B3LYP/6-31G* level. For adsorptions on the Si-H cluster of one surface unit cell, peripheral Si atoms are much more free to make unreasonable moving, This problem can be gradually improved by increasing the number of unit cells. Our current result shows that upon adsorption, at least one of the metal-metal bond is shorten compared to that an isolated molecule. When two alkaline atoms bond, theirσns* filled. Thus, the bonding is actually very weak. When the metal molecule comes onto Si surface, part of the anti-bonding density flows into surface dangling bonds and then strengthens the metal- metal bond. Mg clusters having their bond distances shorten upon O2 adsorbed at neighbor sites is due to the same reason.

Space and water heating contribute over 50% of all the residential building energy consumption and are especially major energy consumers in the cold climates. Meanwhile, conventional furnaces and boilers with energy efficiency limited to below 100% dominate the residential heating in the cold climate, and the electric vapor-compression heat pump capacity and efficiency decline drastically at low ambient temperatures. Thermally driven ammonia-based chemical adsorption (chemisorption) heat pump (CSHP) systems utilize the reversible chemical reaction between the ammonia vapor and solid sorbent to generate heat pumping effect, which can provide heating with much higher energy efficiency than existing cold-climate heating technologies. Despite the significant potential of energy efficiency improvement from existing technologies, most studies in the literature on chemisorption heat pump systems focus on adopting the technology for refrigeration and energy storage applications, with very limited investigations available for using the technology for producing heating in cold climates.

This thesis study is thus conducted to characterize the operation behavior and performance of a CSHP system under cold ambient conditions and further identify optimal design and control for such systems to achieve high performance. In this study, both experimental and modelling approaches are pursued to investigate a CSHP heating system from the perspective of the sorption material using the multiple-stage LiCl-ammonia reactions, to the novel adsorber component with hybrid heat pipe heat exchanger, and finally to the performance of the complete heat pump system. The experimental studies are based on a prototype CSHP system tested to identify the chemical kinetics of the sorption material, as well as the transient performance of the adsorber and the system. The calibrated chemical kinetics are then used in the development of a transient adsorber model to analyze the operation and improve design of the adsorber. The heating COP of the prototype system was measured to be 0.75-1.16 under ambient temperatures of 8-20 C. Finally, a dynamic system model is developed based on the dynamic models of the adsorber and other components in the system. The system model is validated against the experimental data and used to analyze the detailed energy flow and operation dynamic. Based on the inefficiencies revealed by the simulation of the current prototype system, an improved system design with reduced thermal mass and heat loss is introduced. Simulation of the improved system results in heating COP of 1.17 to 1.23 under -13.9 C to 8.3 C ambient, respectively.

Dissertação de Mestrado Integrado em Engenharia Química apresentada à Faculdade de Ciências e Tecnologia
O processo de adsorção, utilizando colunas de leito fixo, mostra-se como um dosprocessos mais vantajosos para a remoção de metais pesados de efluentes industriais. O facto de o leito poder ser regenerado, haver a possibilidade de ser reutilizado e recuperar o metal adsorvido são outros fatores a favor para o seu uso. O crómio, por ser utilizado em processos de galvanoplastia, revestimentos e curtumes, ocorre frequentemente no meio ambiente devido aos efluentes provenientes deste tipo de indústrias.Neste trabalho será estudado o comportamento dinâmico de uma coluna de leito fixoem que o adsorvente utilizado foi obtido no laboratório a partir de casca de pinheiro. No seguimento de trabalhos anteriores, este material, será utilizado como adsorvente para remover o Cr(III). Foram realizadas várias experiências para testar diversos parâmetros operacionais, como a altura do leito, a velocidade superficial do fluido e a concentração de entrada do efluente. Na prática pretende-se obter a máxima fração de leito saturado e prever o comportamento dinâmico do processo de adsorção. Um modelo de natureza mecanística foi desenvolvido de modo a prever a resposta do sistema face a variações dos parâmetros operacionais. Foram incluídas as relações de equilíbrio bem como o modelo Linear Driving Force (LDF) para expressar o transporte de massa intraparticular. Deste modo verificou-se que, para uma concentração de entrada fixa em 100 mg/L, a máxima fração de leito saturado obtidaé de 0.65, para o caso onde se utilizada uma altura de leiro de 6,5 cm e uma velocidade superficial de 14.43×10-2 cm/s. Foi também estudado a influência dos mesmos parâmetros de modo a minimizar a diferença entre o tempo de exaustão onde as condições ótimas são uma altura de leito de 2,5 cm e uma velocidade superficial de 14.43×10-2 cm/s Para além disto, desenho fatorial do tipo Box-Benken-Design foi utilizado de modo a determinar quais as variáveis que mais influenciam a eficiência do processo de adsorção em leito fixo. Utilizando uma regressão linear múltipla, dois modelos empíricos foram construídos onde foram identificas as condições ótimas de operação de modo a maximizar a fração de leito saturado. Por fim, a regeneração do adsorvente foi feita utilizando dois agentes químicos (ácido nítrico e N,N-Bis(carboxymethyl)-DL-alanine trisodium salt). Assim, deste estudo foi possível concluir que o adsorvente testado pode ser utilizado em processos com colunas de leito fixo para a remoção de crómio de efluentes líquidos.
The adsorption process in fixed bed columns, is one of the most advantageous processes for the removal of heavy metals, allowing the treatment of large volumes of effluent. The fact that the bed can be regenerated and the possibility of being reused allowing the recover the adsorbed metal are other factors in favor of its use in large-scale industrial processes. Chromium is the heavy metal selected in this study, because of its relevance in the electroplating, coating and tanning industries. The effluents from these industries may contain detrimentalconcentrations of Cr.This work, aims to analyse the dynamic behavior of a fixed bed column, in which theadsorbent was prepared in the lab. Following the previous work, mercerized pine bark (MPB) will be used as adsorbent to remove Cr (III) and to purify a synthetic effluent. Thus, operational parameters such as bed height, fluid velocity and effluent inlet concentration were tested to obtain the maximum saturated bed fraction and to predict the behavior of the adsorption process for each case. A mechanistic model was developed for predicting the behaviour of the fixedbed, that includes equilibrium parameters and the Linear Driving Force (LDF) approach to express the intraparticular mass transport. For an inlet concentration of 100 mg/L, the maximum saturated bed fraction was 0.65, obtained for the case where a height of 6.5 cm and a superficial velocity of 14.43×10-2 cm/s is used. Moreover, the influence of the same parameters was also studied to minimize the difference between the exhaust time and the break time of the column.In this case, using an inlet concentration of 100 mg/L, a bed height of 2.5 cm and a surface speed of 14.43×10-2 cm/s, were the best conditions.Moreover, a Box-Benken-Design was used to determine the most influent inlet variables (factors) on adsorption efficiency. By using multiple linear regression, empirical models were developed and the optimal operating conditions to maximize the saturated bed fraction were identified. Finally, a regeneration of the adsorbent material was assessed through two chemical agents (nitric acid and N,N-Bis(carboxymethyl)-DL-alanine trisodium salt).From this study, it was possible to conclude that the biosorbent tested can be used in fixed-bed column process for remove chromium from liquid effluents.

The worldwide climate changes and the scarcity of natural resources have been driving measures to reinvent the energy system towards a low-carbon and sustainable model. Adsorption heat pumps (AHPs) are among the alternatives investigated for the creation of nearly zero energy buildings, as they may help to globally decarbonize the society. This work addresses various domains which are important for the research and development of AHPs, namely, experimental characterization of adsorbents, modeling and simulation of adsorption heating units, optimization of the AHPs design and operation, prototype design and benchmarking against more conventional solutions. The overall heating performance of several adsorbents - ETS-10, zeolites (13X, 4A and NaY), silica-gel, MOF CPO-27(Ni), and AQSOATM FAM-Z02 - for water AHPs was investigated under distinct geometric and operating conditions. Regarding ETS-10/water pair, adsorption equilibrium and kinetic properties were measured, along with the effective thermal conductivity and specific heat capacity of ETS-10. These results were used to model and simulate a tubular adsorbent heat exchanger (AHEx). The developed model contemplated material and energy balances, adsorption equilibrium, external heat transfer limitations, and intraparticle mass transport. Values of coefficient of performance (COP) and specific heating power (SHP) in the range 1.36-1.39 and 249-934 W kg−1 were obtained, respectively, for adsorbent bed thicknesses (δ) of 2-6 mm. Sensitivity studies showed that parameters δ and adsorbent regeneration temperature may influence considerably the cycle time (tcycle) and the cyclic adsorption loading swing (ΔWcycle). The ETS-10 was compared against well-known adsorbents like silica gel, zeolite 4A and zeolite 13X, for water AHPs, showing that it is outperformed by zeolite 13X, for bed regeneration, condensation and evaporation at 473 K, 333 K and 278 K, respectively. This was partly attributed to the higher amount of heat generated per cycle when using the pair zeolite 13X/water. For zeolite 13X particle diameters between 0.2 and 0.6 mm, values of COP = 1.48 and SHP = 1141–1254 W kg−1 were obtained. Aiming to reduce computational and numerical efforts in the simulations, the impact of considering some model simplifications while ensuring comparable predictions of the AHP performance for zeolite 13X/water pair was investigated. It was concluded that, e.g., the use of an average and fixed value of the intraparticle mass transfer coefficient is sufficient to predict reliable cycle performances. Since the presence of a binder in the formulation of the adsorbents may harm the adsorption loading and kinetics, the heating performance of commercial 13X and NaY zeolites, with and without binder, was compared for water AHPs, through modeling and simulations. The results unveiled that the performance of zeolite 13X is not significantly penalized by the presence of the binder. The binderless NaY surpassed zeolites 13X for regeneration, condensation, and evaporation temperatures of 398.15-448.15 K, 308.15-328.15 K and 278.15 K, respectively, achieving COP ≤ 1.53 and SHP ≤ 430 W kg-1, essentially due to its higher ΔWcycle. As boosting the market competitiveness of AHPs implies the development of optimized appliances, the potential of combining phenomenological modeling and statistical tools like design of experiments and response surface methodology (DoE/RSM) to aid efficient optimization of AHPs was demonstrated for the pair binderless zeolite NaY/water. A Box-Behnken design with four factors - time of adsorption and desorption, condensation temperature, heat source temperature, bed thickness - and three levels was considered, taking COP and SHP as response variables. The statistical outcomes from DoE/RSM included: (i) Pareto charts displaying the impact ranking of the factors upon COP and SHP, and (ii) polynomial equations to efficiently estimate both performance indicators as function of the factors and vice-versa. These models allowed to map the system performances in a broad range of conditions with a low number of simulations, and to select optimal combinations of geometric and operating parameters to meet pre-established performance requisites. Overall, these results provided insights into the great potential of DoE/RSM for building up optimized AHExs and advanced control strategies of AHPs. Given the myriad of potential applications claimed for metal-organic frameworks (MOFs), for which massive scientific investigation is ongoing, the potential of MOF CPO-27(Ni) for water adsorption heating was investigated in this work, with the aid of modeling and computational simulations. A customized solver and methodology for simulating adsorption heating cycles was developed in OpenFOAM, and validated using data from the literature. An improved AHEx design was considered, consisting of a tube surrounded by a coating composite of CPO-27(Ni)/copper foam. The obtained COPs and SHPs were, respectively, in the interval 1.16-1.39 and 1922-5130 W kg-1, for evaporation, condensation and bed regeneration temperatures of 278.15 K, 308.15 K and 368.15 K, respectively. Under these working conditions, the CPO-27(Ni) was surpassed by the benchmark adsorbent AQSOATM FAM-Z02, which was essentially attributed to lower ΔWcycle and slower intraparticle mass transfer kinetics of the MOF. An experimental installation combining an AHP and a gas water heater (GWH) that may be assembled to test the performance of several adsorbents was designed, and an experimental protocol prepared. Technical specifications of assorted components were defined and suppliers’ proposals analyzed, in order to estimate the budget for such prototype. Finally, a potential concept of an adsorption appliance for domestic hot water production (DHW) was presented and compared against the current Bosch heat pump water heater (HPWH Supraeco W). Despite the eco-friendliness of AHPs, these systems still raise considerable techno-economic challenges, since they require significant dimensions, as well as high complexity and price. In the whole, one concludes that the competitiveness of adsorption technology for DHW production strongly depends on the development of water adsorbents with better performance/price ratio, and on improved formulations like coatings, instead of beds with random particles of adsorbent.
As alterações climáticas e a escassez de recursos naturais têm motivado a criação de medidas para reinventar o sistema energético, rumo a uma economia mais sustentável. As bombas de calor por adsorção (AHP) fazem parte das alternativas investigadas para a criação de edifícios com necessidades energéticas quase nulas. Este trabalho abrange vários domínios com relevância para a investigação e desenvolvimento das AHP, nomeadamente, caraterização de adsorventes, modelação e simulação de unidades de aquecimento por adsorção, otimização do design e operação de AHP, prototipagem e comparação com tecnologias convencionais. Foram investigados os desempenhos de diversos adsorventes em AHP, considerando a água como adsorvato e diferentes condições de operação e de geometria. Os adsorventes selecionados foram o titanossilicato número 10 (ETS-10), três zeólitos (13X, 4A e NaY), a rede metalo-orgânica cristalina (MOF) CPO-27(Ni) e o fosfato de sílica-alumina AQSOATM FAM-Z02. No tocante ao par ETS-10/água, foram medidas isotérmicas de adsorção e propriedades cinéticas, assim como condutividades térmicas e capacidades caloríficas específicas do adsorvente. Estes resultados foram utilizados para modelar e simular um permutador de calor tubular contendo ETS-10. O modelo desenvolvido contemplou balanços de massa e energia, equilíbrio de adsorção, resistência externa à transferência de calor e transporte intraparticular de massa. Para espessuras de leito (δ) de ETS-10 entre 2 e 6 mm, obtiveram-se valores de coeficiente de performance (COP) e de potência específica de aquecimento (SHP) nos intervalos 1.36-1.39 e 249-934 W kg−1, respetivamente. Estudos de sensibilidade mostraram que parâmetros como o δ e a temperatura de regeneração do adsorvente podem influenciar consideravelmente o tempo de ciclo (tciclo) e a capacidade cíclica de adsorção (ΔWciclo) do sistema. O ETS-10 foi comparado com adsorventes bastante conhecidos, tais como, sílica gel e os zeólitos 4A e 13X, tendo-se concluído que o seu desempenho para fins de aquecimento é ultrapassado pelo do zeólito 13X, para regeneração de leito realizada a 473 K, e condensação e evaporação do refrigerante a 333 K e 278 K, respetivamente. Estes resultados foram, em parte, atribuídos a uma maior libertação de calor por ciclo, quando se usa o par 13X/água. Para tamanhos de partícula entre 0.2 e 0.6 mm, este par apresentou COP = 1.48 e SHP no intervalo 1141-1254 W kg−1. Com o objetivo de reduzir o esforço numérico e computacional em simulações, foi estudado o impacto de se introduzirem algumas simplificações no modelo, sem deixar de garantir as previsões razoáveis de desempenho das AHP. Por exemplo, a utilização de um valor médio fixo para o coeficiente intraparticular de transferência de massa é razoável na avaliação dos desempenhos nos ciclos de aquecimento. Uma vez que a presença de agentes ligantes na formulação de adsorventes pode diminuir a capacidade de adsorção e afetar a cinética, foram estudados os desempenhos de aquecimento de adsorventes zeolíticos comerciais (13X e NaY) com e sem ligantes. Os resultados, considerando água como adsorvato, indicaram que a existência de um ligante na formulação do zeólito 13X não afetava consideravelmente o seu desempenho. No âmbito deste estudo, verificou-se ainda que o zeólito NaY sem ligante é o adsorvente mais promissor para temperaturas de regeneração do leito, condensação e evaporação de 398.15-448.15 K, 308.15-328.15 K e 278.15 K, respetivamente, atingindo COP ≤ 1.53 e SHP ≤ 430 W kg-1, essencialmente devido a ΔWciclo mais elevado do que o dos zeólitos 13X. Dado que a otimização das AHP é importante para aumentar a sua competitividade, o potencial de combinar modelação fenomenológica com ferramentas estatísticas, tais como o desenho fatorial de experiências e a metodologia da superfície de resposta (DoE/RSM), foi estudado na otimização de AHP com o par zeólito NaY/água. Para tal, foi considerado o desenho de experiências de Box-Behnken com quatro fatores – tempo de adsorção e dessorção, temperatura de condensação, temperatura da fonte de aquecimento e espessura de leito – e três níveis, sendo COP e SHP as variáveis de resposta. Deste estudo obtiveram-se gráficos de Pareto, mostrando a importância dos diversos fatores no COP e no SHP, e equações polinomiais para estimar de forma expedita o COP e o SHP em função dos fatores e vice-versa. Estas equações permitiram mapear o desempenho da AHP numa ampla gama de condições com um número pequeno de simulações, e ainda identificar combinações ótimas de parâmetros geométricos e de operação para cumprir pré-requisitos de desempenho. Em suma, este estudo mostrou o grande potencial de DoE/RSM para desenvolver componentes mais otimizados e estratégias de controlo avançadas de AHP. Tendo em conta a miríade de potenciais aplicações que tem sido reivindicada para redes metalo-orgânicas cristalinas (MOFs), sobre os quais existe um grande foco da investigação científica, o potencial do MOF CPO-27(Ni) para aplicações de aquecimento por adsorção de água foi investigado usando ferramentas de modelação e simulação computacional. Para este efeito, foi desenvolvido em OpenFOAM um solver customizado e uma metodologia para simular ciclos de aquecimento por adsorção, que foram validados com dados da literatura. Neste estudo, considerou-se uma geometria de leito de adsorvente mais avançada, consistindo num tubo metálico revestido com um filme de um compósito de CPO-27(Ni)/espuma de cobre. Os COP e SHP foram, respetivamente, 1.16-1.39 e 1922-5130 W kg-1, para temperatura de evaporação, condensação e regeneração de leito de 278.15 K, 308.15 K e 368.15 K. Uma comparação deste MOF com o adsorvente de referência para AHP, nomeadamente AQSOATM FAM-Z02, permitiu concluir que o desempenho do CPO-27(Ni) é ultrapassado pelo do segundo, essencialmente devido ao ΔWciclo inferior e à transferência intraparticular de massa mais lenta do CPO-27(Ni). No contexto desta dissertação, foi ainda desenhada uma instalação experimental combinando uma AHP com um esquentador, que poderá ser montada proximamente para testar o desempenho de diversos adsorventes, tendo sido elaborado o respetivo protocolo. As especificações técnicas de diversos componentes para o protótipo foram definidas e foram analisadas propostas de vários fornecedores, a partir das quais se estimou o custo da instalação. Finalmente, foi desenhado um possível conceito de uma AHP para aquecimento de água doméstica, o qual foi comparado com a atual bomba de calor da Bosch para este fim (Supraeco W). Apesar dos benefícios ambientais das AHP, concluiu-se que estes sistemas suscitam ainda grandes desafios técnico-económicos, uma vez que exigem dimensões significativas, bem como complexidade e preço elevados. No cômputo geral, conclui-se que a competitividade da tecnologia de aquecimento de água doméstica por adsorção depende largamente do desenvolvimento de adsorventes de água com melhor rácio desempenho/preço e da aposta em formulações mais eficientes como, por exemplo, na preparação de filmes ao invés de enchimentos aleatórios de partículas de adsorvente.
Programa Doutoral em Engenharia da Refinação, Petroquímica e Química

碩士
中國文化大學
應用化學研究所
95
We investigated bonding and optimized geometries of Seperated boron atoms and B3 molecule adsorbed on the Si(111) surfaces at the B3LYP/6-31G* level. In the case of Si(111),different sizes of Si-H clusters were used, depending on the extent of marginal distortion of the clusters. General speaking, the bond lengths in B3 adsorbates are greatly reduced which mean that boron atoms and B3 molecule tend to from stronger boron molecule on the Si(111) surface .

碩士
中國文化大學
應用化學研究所
95
Abstract We investigated bonding and optimized geometries of 、Li2 and Li3 adsorbed on the Si(111) surfaces at the B3LYP/6-31G* level. Different sizes of Si-H clusters were used to represend He Si(111) ideal surface﹐depending on the extent of marginal distortion of the clusters. General speaking, the bond lengths in Li2 and Li3 adsorbates are enlarged due to the dissociation of the Lithium molecules on the surface﹐The lithium atoms then tend to saturate a more surface dangling bonds as they can．

MENVSC
Department of Ecology and Resource Management
Some boreholes in South Africa which serve as a source of drinking water for rural communities are reported to have high fluoride concentration, much above the WHO guideline of 1.5 mg/L. This study aimed at activating aluminosilicate clay soil mechanochemically, modifying aluminosilicate clay soil with Al-oxide and fabricating porous ceramic granules using Al-oxide modified mechanochemically activated aluminosilicate clay soil/ mechanochemically activated clay soil/ corn starch and evaluating their performances in defluoridation of groundwater. The raw clay materials were mechanochemically activated for 5, 10, 15 and 30 minutes for physicochemical transformation of the solid aggregate. The morphology of the samples showed the honeycomb structure. The surface area analyses of samples using Brunauer–Emmett–Teller (BET) gave the highest surface area of 50.5228 m2/g at 30 min activation time. Hence, the optimum activation time was 30 min. The Fourier Transform Infrared (FT-IR) analysis showed increase in the absorbance of FT-IR by Si-O-H groups at 510 cm-1 with increasing milling time. This is evidence that more surface Si-O-H groups were available at higher particle surface area that would be necessary to interact with fluoride. X-ray diffraction (XRD) analyses revealed that, at 30 minutes milling time, the peak broadening is intensified whereas the reflection peak intensities decreased. The X-ray fluorescence spectrometry (XRF) results for 30 minutes milling time showed that silica and alumina were the highest components in the clay soil. Using the activated clay in batch defluoridation of fluoride-spiked water, a maximum fluoride removal of 41% was achieved at a pHe of 2.41. The initial fluoride concentration was 9 mg/L while the sorbent dosage was 0.6 g/100 mL and the contact time being 30 minutes. The adsorption data fitted to both Langmuir and Freundlich isotherms. The adsorption data fitted only the pseudo-second-order kinetic, showing chemisorption. Optimization of Al3+ concentration for modification was carried out by modifying the mechanochemical activated aluminosilicate clay soil with different concentrations of Al3+ from which the optimum modification was achieved with 1.5 M. Characterisation studies on the Al-oxide modified mechanochemically activated aluminosilicate clay soil by SEM, BET, FT-IR, XRD and XRF, analyses were carried out to determine the resultant changes in physicochemical properties of the adsorbent owing to modification. The SEM image of Al-oxide modified mechanochemically activated clay soil showed many small pores and honey-comb structure on the surface of different images. The BET surface area and the BDH adsorption cumulative area of the Al-oxide modified mechanochemically activated v aluminosilicate clay soil were more than double those for the raw clay soil. There was also an increase in pore volume of the Al-oxide modified mechanochemically activated aluminosilicate clay soil. The FT-IR spectra showed that there was increase in the absorbance by the Si-OH, H-O-H, Al-O-H and Si-O-Al. The equilibrium pH of solution was higher than the point-of-zero charge (pHpzc) implying that fluoride removal occurred at solution pH > pHpzc where the net surface charge of the mechanochemically activated clay aluminosilicate soil was negative.The efficiency of 1.5 M Al-oxide modified aluminosilicate clay soil to remove fluoride from water was studied and found to be 96.5 % at pHe 6.86, contact time of 30 minutes and dosage of 0.3 g/100 mL for 10 mg/L fluoride solution at 200 rpm shaking speed. The result shows that Al-oxide modified mechanochemically activated aluminosilicate clay soil is effective for defluoridation. The adsorption data fitted to both Langmuir and Freundlich isotherms. The adsorption data fitted only the pseudo-second-order kinetic, showing chemisorption. Al-oxide modified mechanochemically activated aluminosilicate clay soil was tested for fluoride removal on field water and the percentage fluoride removal was 96.5 % at the dosage of 0.6 g/100 mL with the pHe of 6.48. The optimum Al-oxide modified mechanochemically activated aluminosilicate clay soil/ mechanochemically activated clay soil/ corn starch mixing ratio for fabrication of porous ceramic granules was determined by varying ratios and temperature. The optimum ratio found was 20:5:1.The porous ceramic granules were characterised using SEM, BET, FT-IR, XRD and XRF. SEM analysis showed that the porous ceramic granules have the porous structure of the organic foam template. The porous ceramic granule showed an increase in pore surface area and volume as compared to mechanochemically activated aluminosilicate clay soil. The FT-IR showed the presence of a strong broad bending and stretching vibrations band at about 993 cm-1 which shows the presence of Si–O–Si bonds. Mineralogical characterisation showed the presence of quartz, albite, horneblende and microcline as the main minerals of the calcined porous ceramic granules. The major oxides of the porous ceramic granules as shown by XRF analysis were SiO2, Al2O3, MnO and Na2O. The porous ceramic granules reduced the concentrations of fluoride in the water from 10 to 3.31 mg/L. The optimum adsorption capacity was 0.6648 mg/g at a pHe of 6.32 and the percentage fluoride removal was 66.9 % at an adsorbent dosage of 1.0063 g/100 mL and a temperature of 600 ⁰C. The porous ceramic granules were tested for fluoride removal on field water and the percentage fluoride removal was 45.4 % at the dosage of 1.0009 g/100 mL with the pHe of 7.87. Mechanochemically activated aluminosilicate clay soil showed higher adsorption capacity at acidic pH, therefore it is recommended that future work should focus on improving their adsorption capacity at wider range of pH. The porous ceramic granules can also be evaluated in column dynamic flow experiments.

碩士
中國文化大學
應用化學研究所
95
Abstract We investigated bonding and optimized geometries of Na、Na2 and Na3 adsorbed on the Si(111) surfaces at the B3LYP/6-31G* level. While in the case of Si(111),different sizes of Si-H clusters were used, depending on the extent of marginal distortion of the clusters. Finally, we put O2 onto the neighbor site of sodium adsorbate to see how oxygen interacts with metal and surfaces. This is expected to understand the oxidization process in the semiconductor industry. General speaking, the bond lengths in Na2 and Na3 adsorbates are greatly reduced due to the flowing of charge density from metal antibonding orbitals into the surface dangling bonds.

碩士
中國文化大學
應用化學研究所
95
Adsorption of alkali atom on silicon surface has been applied to microelectronic and catalytical industries for many years. My research is investigate bonding and optimize Al Al2 Al3 adsorb on the Si(111) surface at the B3LYP/6-31G* level. In the case of Si(100), the Si9H12 cluster was used to represent the surface unit with one Si=Si surface dimmer, while in the case of Si(111),different sizes of Si-H clusters were used, depending on the extent of marginal distortion of the clusters. For adsorptions on the Si-H cluster of one surface unit cell, peripheral Si atoms are much free to make unreasonable moving results, we can solve this problem by increasing the number of unit cells. But the more unit cells we use, the more computation time we need.