M.Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / This thesis presents a slight on desulphurization process of the commercial diesel fuel using the carbon-based metal oxide nanocomposites such as graphene oxide, ZnO, rGO as a nano-adsorbent, activated carbon (PAC and AC) and charcoal Granular active carbon (GAC) to produce a fuel of less than 10 ppm sulphur content. Due to the high percentage of sulphur compounds in the fuel causing air pollution, acid rain and other problems related to combustion process. The synthesised of sorbents were achieved using incipient impregnation, microwaved-assisted and chemical exfoliation methods. The materials were characterized using Thermogrametric Analyzer (TGA), Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD), Brunauer, Emmett and Teller (BET). The examination effect of operating conditions on the adsorption capacity with DBT and Sulphur compounds adsorption, the isotherms and the adsorption kinetic models were evaluated. The experimental data for PAC and AC were well suited to Freundlich isotherm and pseudo second-order kinetic models. The results shown that the sulphur feed concentration, the space velocity and the functional groups of the adsorbents have a considerable effect on the adsorption. In addition, it was observed that the temperature in the range of 30 to 80oC has a significant effect on the adsorption of Sulphur compounds from diesel fuel using 20 wt.% of sorbents. The rGO substrate which contained abundant oxygen functional groups was confirmed to promote the dispersion metal oxide and increased the adsorption efficiency of sulphur compounds (H2S and SO2) by providing oxygen ions weakly bound to the sulphur molecules. For the desulfurization process by adsorption, PAC and AC exhibited a better affinity for 80% removal of sulphur compared to the GAC and GO. The effects of metal species such as zinc oxide (ZnO) and reduced graphite oxide (rGO) composite on the adsorption capacity of hydrogen sulphide (H2S) were investigated. It was found that depending on the copper load, the adsorption capacity of H2S increased up to 20 times compared to pure ZnO. To study the oxidation changes on copper and zinc oxides, crystallite analysis by XRD and chemical state analysis by XPS were performed.

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Combustion of coal is one of the primary sources of electricity generation worldwide today. Coal contains different chemicals that cause particulate matter(PM) and sulfur dioxide (SO2) emissions. These are health hazards and are responsible for deteriorating the ambient air quality. Particulate matter also forms ash deposits inside the coal combustor, which in turn decreases the energy efficiency of the power plants. Using biomass as a fuel in these utility boilers can potentially reduce the problems of particulate matter emissions and ash deposition, and can significantly reduce the SO2 emissions. However, biomass needs to be pretreated to make its properties similar to coal in terms of energy density, grindability, and durability before it can be fired in utility boilers. Steam explosion is one of the leading biomass pretreatment methods that enhances the physicochemical properties of biomass. A comprehensive review of the steam explosion process, its product properties, its comparison with other treatment processes, as well as its economic analysis and lifecycle assessment, have been explored in this work. Steam-exploded biomass has been co-combusted with bituminous coal in a 1500 kWth combustor to analyze the ash aerosol particle size distribution, composition, and deposition behavior. The primary results of these tests showed that both particulate matter emissions and ash deposition amount reduced significantly as more biomass was co-fired with coal. The submicron-sized particulate matter concentration showed a high correlation with the final mass of ash deposits (R2 > 0.96). Predicting ash deposition rates is important during the combustion of solid fuels. A Machine Learning tool was applied and trained with a fuel composition database of 92 fuels obtained from a thermodynamic equilibrium software (FactSage). When fully operational, this model should be integrated with an existing ash deposition model, which should make it self-sufficient in terms of generating equilibrium composition data. SO2 emissions were analyzed during the co-combustion of biomass and coal, and a synergistic decrease in SO2 emissions was observed with higher biomass blends. Experiments were conducted in a full-scale 471 MWe furnace to analyze the SO2 emissions, and an 85%-15% blend of coal and biomass was responsible for a 28.1% reduction in emissions and 22.1% reduction in the lime slurry utilization in the flue gas desulfurization (FGD) towers compared to pure coal combustion. Ash deposit characterizations by energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) combined with thermodynamic equilibrium simulations revealed that calcium and potassium were responsible for this synergistic reduction as these metals captured the SO2 from the flue gases and retained them in the ash phase. The SO2 research was important since the current literature is deficient in research conducted at suspension-fired full-scale utility boilers to reduce SO2 emissions by co-firing coal and biomass blends. The research in this dissertation should provide valuable insights to the energy industries that are considering a transformation of fuel portfolio from coal to biomass and explore how the mineral matter present in pretreated biomass would behave inside a utility boiler. The primary conclusions are that during the co-combustion of coal and biomass, ash deposition mass and particulate matter ash load decreased, and SO2 emission saw a synergistic reduction in emissions due to higher calcium and potassium content in biomass compared to pure coal combustion.

M. Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology): Vaal University of Technology / Strict environmental regulation on flue gas emission has led to the implementation of FGD technologies in power stations. Wet FGD technology is commonly used because it has high SO2 removal efficiency, high sorbent utilization and due to availability of the sorbent (limestone) used. SO2 is removed by passing flue gas through the absorber where it reacts with the slurry containing calcium ions which is obtained by dissolution. This study presents the findings of the dissolution of a calcium-based material (limestone) for wet FGD process. This was done using a pH stat apparatus and adipic acid as acid titrant. Adipic acid was used because of its buffering effect in wet FGD process. The conditions used for this study are similar to what is encountered in a wet FGD process. The extent of dissolution was determined by analyzing the amount of calcium ions in solution at different dissolution periods. The dissolution kinetics were correlated to the shrinking core model and it was found out that chemical reaction at the surface of the particle is the rate controlling step. This study also investigated the dissolution of coal fly ash and bottom ash. Their dissolution kinetics showed that the diffusion through the product layer was the rate controlling step due to an ash layer formed around the particle. The formation of ash layer was attributed to pozzolanic reaction products which is calcium-alumino-silicate (anorthite) compounds were formed after dissolution. The effect of fly ash on the dissolution of rate of limestone was also studied using response surface methodology. Limestone reactivity was found to increase with increase in the amount of fly ash added and the pH was found to be strong function of the rate constant compared to other dissolution variables. The presence of silica and alumina in fly ash led to a significant increase in the specific surface area due to hydration products formed after dissolution. / Eskom

Cette thèse porte sur l'étude de la caractérisation et le traitement de saumures alcalines. La carbonatation directe de saumures résiduaires (SR), par introduction d'une partie du CO2 issu de fumées industrielles, est réalisée dans un souhait de réduction des émissions de CO2 et en vue d'une valorisation potentielle des produits obtenus. Cette recherche se concentre sur l'étude des composés carbonatés, l'objectif général est d'établir le lien entre la réactivité des carbonates et leur valorisation (ici, désulfuration de fumées acides). Les SR sont complexes, l'étude de leur composition chimique et minéralogique a été réalisée en partie par spectroscopie Raman afin de mettre en évidence les interactions OH-Cl dans les échantillons humides. Les différents hydroxydes sont consommés au cours de la carbonatation pour précipiter des carbonates de calcium (calcite, aragonite). La composition chimique détermine les réactions de carbonatation alors que les paramètres physiques influencent la vitesse des réactions ainsi que la morphologie et la pureté des carbonates. L'évolution des phases au cours de la carbonatation des SR a été suivie par spectroscopie et un premier modèle statistique de prédiction des concentrations en carbonates a été développé. La deuxième partie de ce travail porte sur la caractérisation des carbonates obtenus et des paramètres, tel que l'hydratation, pouvant influencer leur valorisation. L'importance de l'hydratation dans la réactivité des produits DECALCO a été observée de l'échelle microscopique au pilote semi-industriel. Les essais de désulfuration de fumées acides ont été menés avec des taux de conversion du SO2 atteignant 65 à 70 % / This study is a contribution to the characterization and the treatment of alkaline industrial wastes. The direct carbonation of residual brines (RB) by CO2 bubbling results in a gas emission reduction and a potentially valorization of resulting products. This research was focused on carbonate products. The main objective is to link reactivity and valorization (here, desulfurization of industrial fumes). The RB are complex, their chemical and mineralogical composition was studied in particular by Raman spectroscopy to monitor OH-Cl interaction in humid samples. The different hydroxides phases are consumed during carbonation to precipitate calcium carbonates (calcite and aragonite). The chemical composition of RB determines the main part of the reaction of carbonation whereas physical parameters influence the reaction kinetics, the by-products morphology and purity. The feasibility of on-line monitoring of the phases evolution during carbonation using spectroscopy has been validated and a first statistical model for the prediction of carbonate concentration has been developed. The second part of this works concerns the characterization of precipitated carbonates and some parameters as hydration which can influence their valorization. The importance of hydration on the carbonates reactivity was observed in microscopy and at pilot scale. Desulfurization tests of industrial fumes in semi-humid way provided a conversion rate of SO2 ranging between 65 and 70%

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

Protein-Arrays sind das Mittel der Wahl, um eine Vielzahl von Proteinen parallel zu untersuchen. Ziele dieser Untersuchungen sind meistens Proteininteraktionsnetzwerke zu entdecken oder besser verstehen zu können. Bisher wurden die benötigten Proteine fast ausschließlich mit biologischen Methoden gewonnen. Diese bieten allerdings keinen generellen Zugang zu posttranslational-modi-fizierten (PTM)-Proteinen. Somit war es bisher nicht möglich den Einfluss von PTMs auf Protein-Protein-Interaktionen (PPIs) im Arrayformat zu untersuchen. Die chemische Synthese kann dagegen Proteine mit ortsspezifischen PTMs liefern. Daher ist es verwunderlich, dass bislang noch keine Berichte über chemisch hergestellte PTM-Protein-Arrays existieren, besonders da PTMs meist entscheidend für proteomische Interaktionsnetzwerke sind. In der vorliegenden Arbeit wird eine Methodik beschrieben, die es ermöglicht PTM-modifizierte Protein-Domänen-Arrays auf der Oberfläche zu synthetisieren und zu analysieren. Mit der Methodik wurden 20 SH3-Domänen synthetisiert und 64 PPIs gemessen. Neben vier Hefe-SH3-Domänen wurden je acht humane (Phospho)SH3-Domänen der Abl- und Arg(Abl2)-Tyrosinkinase synthetisiert und funktionell untersucht. Es wurde gefunden, dass die Ligandenspezifität von Abl-SH3-Domänen durch Phosphorylierung feinreguliert wird. Je nach Phosphorylierungsmustern wurde die Affinität für spezifische Liganden erhöht oder erniedrigt. Der Ursprung dieser Phosphoregulierung wurde für die Abl-SH3-Domäne mit Hilfe der NMR-Spektroskopie und durch Zellexperimente versucht zu entschlüsseln und weiter validiert. / Protein-arrays are the method of choice to investigate a variety of proteins in a parallel fashion. Objectives of these studies are mostly to discover or to investigate protein interaction networks. So far, the necessary proteins were almost exclusively gained by biological methods. Unfortunately, generic access to proteins bearing post-translational modifications (PTM) is not provided by these techniques. Therefore, it was not possible to investigate the impact of PTMs on protein-protein-interactions (PPIs) on arrays so far. Chemical synthesis in contrast offers proteins with site-specific PTM incorporation. In this context, it is surprising, that chemical methods of PTM-protein array synthesis remained virtually unexplored, especially since these modifications are usually crucial for proteomic interaction networks. In this thesis, a methodology is described, that allows to synthesize and functional analyse post-translationally modified protein domain arrays on the surface. By using this methodology, 20 SH3 domains were synthesized and 64 protein-pep-tide interactions were measured. In addition to 4 yeast SH3 domains, 8 human (phospho) SH3 domains of the Abl and Arg(Abl2) tyrosine kinase were synthesized and functionally investigated. The experiments revealed that phosphorylation might serve as a means to fine tune the ligand recognition. Depending on the phosphorylation pattern the affinity to specific interaction partners were enhanced or reduced. The origin of this phosphoregulation was further investigated for the Abl SH3 domain by means of NMR spectroscopy and cellular experiments.

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