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Thompson, Laura M. "The depletion of nitric oxide by reaction with molten sodium carbonate and sodium carbonate/sodium sulfide mixtures." Diss., Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/5797.
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Sozen, Gulgun. "The autocausticizing of sodium carbonate with colemanite." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25138.
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Autocausticizing, a new method to regenerate sodium hydroxide from the sodium carbonate, is intended to replace the conventional Kraft Recovery System which uses calcium hydroxide produced in a lime kiln for this purpose. It is defined as the self-induced expulsion of carbon dioxide bound in the smelt by using certain amphoteric oxides. Thus autocausticizing can eliminate the need for a lime cycle and hence reduce the Kraft process capital and operating costs.
The reactions between sodium carbonate and a number of amphoteric oxides have been reported in the literature. Patents have been issued on the use of titanium dioxide, iron oxide and sodium borates for this purpose.
The sodium borates have the advantage of a high reaction rate, but are totally soluble and must be carried throughout the whole Kraft cycle. In this research colemanite (calcium borate) which is mined as a cheap mineral in California and in Turkey was studied as an autocausticizing agent. Since it is partially soluble and most likely can be recycled, it would eliminate the problems associated with the use of soluble borates.
Experiments were performed both isothermally and under constant heating rate conditions. Isothermal studies were made with Ti0₂, alumina and colemanite to compare their performances as autocausticizing agents at 900°C and 1000°C for various reaction times in an electric furnace. The second group of experiments was made using a differential Chermogravimetric (TG) analyzer. In these experiments mixtures with 20 to 80 weight percent colemanite in sodium carbonate were heated at a constant heating rate of 10°K/min in the range of 190-1000°C. The results indicate that two reaction were involved. Above the stoichiometric colemanite concentration the colemanite and sodium carbonate had reacted completely by a temperature of about 700°C. Above that temperature the impurities in the colemanite appeared to catalyze the decomposition of sodium carbonate if the colemanite concentration was less than the stoichiometric amount needed.
TG data were analyzed for the first and second reactions between the temperature ranges of 190-700°C and 700-1000°C respectively. Kinetic models were developed In terms of the reaction order, activation energy and frequency factor. The first reaction was found to be zero order on sodium carbonate concentration. The results also showed that the activation energy and frequency factor were functions of the colemanite concentration in the mixtures. As a result the rate was affected by the amount of colemanite used. The same was true for the second reaction except the reaction was first order. The concentrations
predicted for the isothermal tests by the model were compared with the results of the isothermal study for various colemanite concentrations. Reasonable agreement was found except for the values at lower conversions, which might be due to the Increased importance of the diffusion of CO₂ from the mixtures in the case of Isothermal runs. It was also found that it is possible to obtain conversions as high as 85 percent with 40 percent colemanite in 20 minutes. Promising results were obtained from the recycle tests as well.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
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Eames, Douglas J. "Direct causticizing of sodium carbonate with manganese oxide." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/7026.
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Shaikh, Amjad A. "Conversion of sodium carbohydrate to sodium carbonate monohydrate in an inclined horizontal rotating cylinder." Thesis, University of Sheffield, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.444877.
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Dickinson, Clive F. "The kinetics of glass making reactions involving sodium carbonate." Thesis, University of Salford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271248.
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Jadon, Ankita. "Interactions between sodium carbonate aerosols and iodine fission-products." Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1R021/document.
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L’analyse de sûreté des réacteurs à neutrons rapides refroidis au sodium de Génération IV nécessite l'étude des conséquences d'un accident grave en cas de rejet dans l'environnement du sodium et des radionucléides qu'il transporte (terme source chimique et radiologique). Le terme source global dépend donc à la fois de la spéciation chimique des aérosols de sodium, issus de la combustion du sodium dans l'enceinte, et de leurs interactions avec les radionucléides. Au cours de cette thèse, les interactions entre le carbonate de sodium et les produits de fission gazeux iodés (I2 et HI) ont été étudiées aux échelles atomique et macroscopique, via une double approche théorique et expérimentale. Une expression analytique de l'isotherme d'adsorption a été développée. La stabilité relative des surfaces du carbonate de sodium a été déterminée par des calculs ab initio utilisant la théorie de la densité fonctionnelle. La réactivité de l'iode a été étudiée pour les surfaces les plus stables et les isothermes d'adsorption évaluées. En parallèle, la cinétique de capture de l'iode moléculaire par le carbonate de sodium a été déterminée expérimentalement pour différentes conditions. L'ensemble des résultats montrent une capture efficace de l'iode moléculaire par le carbonate de sodium à 373 K, variant selon la pression partielle d'iode et la surface du carbonate. Pour les conditions représentatives d'un accident grave, les sites d'adsorption de la surface de carbonate de sodium la plus favorable seront majoritairement vides ou doublement occupés selon la pression partielle d'iode moléculaire, conduisant à une pression d'équilibre inférieure à 2x10-4 bar à 373 KThe safety analysis of Generation IV sodium-cooled fast neutron reactors requires the study of the consequences of a severe accident in case of release into the environment of sodium and the radionuclides it carries (term chemical and radiological source). The global source term therefore depends on both the chemical speciation of sodium aerosols, resulting from the combustion of sodium in the containment, and their interactions with radionuclides. During this thesis, the interactions between sodium carbonate and iodinated gaseous fission products (I2 and HI) were studied at the atomic and macroscopic scales, via a combined theoretical and experimental approach. An analytical expression of the adsorption isotherm has been developed. The relative stability of the sodium carbonate surfaces was determined by ab initio calculations using density functional theory. The reactivity of iodine has been studied for the most stable surfaces and the adsorption isotherms evaluated. In parallel, the kinetics of capture of molecular iodine by sodium carbonate has been determined experimentally for different boundary conditions.The results show an effective capture of the molecular iodine by sodium carbonate at 373 K, varying according to the partial pressure of iodine and the surface of the carbonate sorbent. For the representative conditions of a severe accident, the adsorption sites of the most favorable sodium carbonate surfaces will be mostly bare or doubly occupied depending on the partial pressure of molecular iodine; leading to an equilibrium pressure of less than 2x10-4 bar at 373 K
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Al-Wohoush, Mohammad. "Selective absorption of hydrogen sulfide in aqueous sodium carbonate solutions." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69785.
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The absorption of hydrogen sulfide and carbon dioxide in aqueous sodium carbonate solution was studied on a pilot scale packed column operated counter-currently under atmospheric pressure. The absorption column was 7.5 cm in diameter and 150 cm in height and packed randomly with 6 mm Intalox Saddles. It was designed to remove hydrogen sulfide from a gas mixture of 1.5% hydrogen sulfide and 15% carbon dioxide at an efficiency of 95%. Reliability of the experimental setup has been perused by investigating the residence time distribution of the gas phase in the column and by studying the absorption of carbon dioxide in water.In the first part of the experimental work, it was found that carbonate concentration has a major effect on the absorption of hydrogen sulfide, while the absorption of carbon dioxide is affected significantly by temperature. In the second part of the experimental work, the influence of all parameters on the absorption of hydrogen sulfide and carbon dioxide has been investigated. Results were analyzed in terms of removal efficiencies, the overall mass transfer coefficients and the selectivity of the process for hydrogen sulfide. It was observed that hydrogen sulfide can be absorbed selectively in the presence of carbon dioxide at low operating temperatures, high carbonate concentration and high gas to liquid ratios. A removal efficiency of hydrogen sulfide of about 92% accompanied with about 17% of initial amount of carbon dioxide has been achieved. (Abstract shortened by UMI.)
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Belhimer, E. "Stress corrosion cracking of pipeline steels and pure iron in a sodium carbonate-sodium bicarbonate solution." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376310.
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Gagnon, Gerard R. "The Colloidal Properties and Rheological Behavior of Precipitated Calcium Carbonate Suspensions Dispersed with Sodium Polyacrylate." Fogler Library, University of Maine, 2008. http://www.library.umaine.edu/theses/pdf/GagnonG2008.pdf.
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Akyildiz, Ugur. "Effect Of Sodium Carbonate On Carbothermic Formation Of Hexagonal Boron Nitride." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612579/index.pdf.
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Effect of Na2CO3 on formation of hexagonal boron nitride (h-BN) by carbothermic method has been studied by subjecting B2O3-C and Na2CO3-added B2O3-C mixtures to N2 (g) atmosphere. Na2CO3 amount in the mixtures was changed in the range of 0-40 wt. %. Time and temperature were used as experimental variables. Reaction products were analyzed by XRD and scanning electron microscope. Na2CO3 was found to increase both the amount and the particle size of h-BN similar to CaCO3 [1]. Na2CO3 was found to be less effective than CaCO3 in increasing the amount while it was more effective than CaCO3 in increasing the particle size of h-BN forming.
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Rechberger, Johann. "Stress corrosion cracking of rotor steels in carbonate/bicarbonate and sodium hydroxide solutions." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/26321.
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In this study, the stress corrosion behavior of 3.5%NiCrMoV and 1%CrMoV steels was investigated. Tests were conducted at 95°C in carbonate/bicarbonate and sodium hydroxide solutions. Results from slow strain rate tensile tests and fracture mechanics experiments were compared. A new, easily machinable, specimen geometry for fracture mechanics experiments was tested. The influence of pH, potential, microstructure and inclusions were studied.
Stress corrosion cracking (SCC) was found with all three steels in the 3.5M NaOH solution at active, passive and transpassive potentials. In the 1M carbonate/
bicarbonate solutions, the 1%CrMoV steels showed very severe cracking only during slow strain rate experiments. No major difference in cracking behavior was found between a regular 3.5%NiCrMoV steel and a super clean 3.5%NiCrMoV steel with low Mn and Si content. In acidic CO₂/H₂O environments, crack tip blunting was observed due to strong dissolution processes.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Gudavalli, Ravi Krishna. "Effect of pH and temperature on the carbonate promoted dissolution of sodium meta-autunite." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/773.
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Release of uranium from Na-autunite, an artificial mineral created as a result of polyphosphate injection in the subsurface at the DOE Hanford Site, takes place during slow dissolution of the mineral structure. Stability information of the uranyl-phosphate phases is limited to conditions involving pH, temperature, and a few aqueous organic materials. The carbonate ion, which creates very strong complexes with uranium, is the predominant ion in the groundwater composition.
The polyphosphate technology with the formation of autunite was identified as the most feasible remediation strategy to sequester uranium in contaminated groundwater and soil in situ. The objectives of the experimental work were (i) to quantify the effect of bicarbonate on the stability of synthetic sodium meta-autunite created as a result of uranium stabilization through polyphosphate injection, (ii) calculate the kinetic rate law parameters of the uranium release from Na-autunite during dissolution, and (iii) to compare the process parameters with those obtained for natural calcium meta-autunite.
Experiments were conducted using SPTF apparatus, which consists of syringe pumps for controlling flow rate, Teflon reactors and a heating/cooling system. 0.25 grams of synthetic Na-autunite was placed in the reactor and buffer solutions with varying bicarbonate concentrations (0.0005 to 0.003 M) at different pH (6 - 11) were pumped through the reactors. Experiments were conducted at four different temperatures in the range of 5 - 60oC.
It was concluded that the rate of release of uranium from synthetic Na-autunite is directly correlated to the bicarbonate concentration. The rate of release of uranium increased from 1.90 x 10-12 at pH 6 to 2.64 x 10-10 (mol m-2 s-1) at pH 11 at 23oC over the bicarbonate concentration range tested. The activation energy values were invariant with the change in the bicarbonate concentration; however, pH is shown to influence the activation energy values. Uranyl hydroxides and uranyl carbonates complexes helped accelerate the dissolution of autunite mineral.
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Gershon, Daniel. "Kinetics of Autocausticization Using Borates in a Black Liquor Gasification Process." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4762.
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The path of research in the pulp and paper industry is heading towards the elimination of the lime cycle, which requires large amounts of energy, and changing the conventional recovery boiler system to a gasification process that will reduce the possibility of smelt water explosions while meeting future environmental regulations. Research has been carried out on both gasification processes and on causticizing processes that can replace or complement the lime cycle, however very little research has gone into the actual kinetics of causticization using black liquor in gasification processes. This research project fills in some of the missing knowledge in the area of kinetics of autocausticization reactions, which entails the use of borates as the autocausticizing agent. A temperature dependent kinetic model coupled with a mass transfer coefficient has been developed and compared to experimental data.
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Nohlgren, Ingrid. "Recovery of kraft black liquor using the titanate process : kinetics of the direct causticization reaction between sodium tri-titanate and sodium carbonate." Licentiate thesis, Luleå tekniska universitet, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18189.
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The solid state reaction between sodium tri-titanate and sodium carbonate, forming mainly sodium penta-titanate, was investigated. Experiments were carried out in a micro-differential reactor made of quartz glass at various temperatures between 800°C and 880°C and in a pilot fluidized bed reactor operated in a semi-batch mode. In the micro-differential reactor, basic kinetic data was obtained by measuring the release of carbon dioxide during the reaction. Different kinetic models were considered to describe the conversion, such as the Valensi-Carter model for diffusion controlled reaction rates and the phase-boundary model for first-order reaction kinetics. Furthermore, a model that included both diffusion in the solid material and the chemical kinetics was derived. This model described the experimental data obtained in the micro-differential reactor very well. Finally, rating models describing the conversion obtained in a fluidized bed and in an entrained flow reactor were developed.Godkänd; 1999; 20070403 (ysko)
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Dubouis, Michel. "Régénération de la soude à partir de solutions de carbonate de sodium par des procédés électromembranaires." Grenoble INPG, 1993. http://www.theses.fr/1993INPG0051.
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Differents procedes electromembranaires sont concus et etudies pour regenerer de la soude a partir de solutions de carbonate de sodium. En presence d'especes oxydables en faibles quantites, la regeneration s'effectue avec une cellule a une seule membrane permselective echangeuse de cations. Pour eviter l'oxydation de ces especes, par exemple le sulfure (na#2s) de la liqueur verte du procede kraft, le procede electromembranaire le plus adapte par sa simplicite et par sa capacite de fonctionnement sur le long terme, est constitue d'un electrolyseur a deux membranes echangeuses de cations, precede d'un reacteur d'acidification pour le degagement des gaz; dans la boucle reacteur-compartiment central de la cellule d'electrolyse, circule une solution de sulfate de sodium acidifiee. Une autre configuration de l'electrolyseur du procede est envisagee et testee avec une membrane echangeuse d'anions et une membrane echangeuse de cations suivant le procede classique d'electro-electrodialyse du sulfate de sodium. Ce procede est aussi compare a un electrolyseur a deux membranes echangeuses de cations avec introduction directe de la solution de carbonate et de sulfure de sodium dans le compartiment central ou se produit le degagement des gaz. Les membranes echangeuses de cations et plus particulierement les membranes echangeuses d'anions, separant le compartiment anodique du compartiment central de l'electrolyseur, sont etudiees par la methode des radiotraceurs et par spectrometrie raman. Ces procedes produisent de la soude qui peut etre aussi concentree que dans le procede chlore-soude a membrane et de l'hydrogene relativement pur dont l'utilisation par une anode a hydrogene est testee. Finalement, si les problemes d'environnement remettent en cause le procede bien etabli du four a chaux, la rentabilite de ces differents procedes devra etre reconsideree
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Blanco, Andujar C. "Sodium carbonate mediated synthesis of iron oxide nanoparticles to improve magnetic hyperthermia efficiency and induce apoptosis." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1430360/.
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Iron oxide nanoparticles are a popular choice for many current technologies, especially those with applications in biology and medicine. Novel syntheses that aim to improve their physicochemical properties, or adapt them to distinct practical applications, are constantly being reported. However, the reproducibility of these methods is not commonly studied, leading to promising products that have little chance of being commercially manufactured. Adherence to good manufacturing practice standards is a decisive factor in determining whether a material may be granted regulatory approval for industrial or clinical use. As such, tight control on the synthetic conditions is crucial to obtain consistent products. In this work initial experimentation was focused on the use of sodium carbonate―an environmentally friendly base―for the synthesis of iron oxide nanoparticles. Mild reaction conditions and slow kinetics allowed for the study of the reaction mechanism and led to controllable and reproducible results. However, functionalised suspensions could not be obtained due to the adsorption of carbonate onto the nanoparticle surface. A microwave reactor was then introduced to take advantage of the surface selective heating effect, aiding ligand exchange and enabling the production of nanoparticles with a range of surface functionalities. Their potential for magnetic hyperthermia, a promising therapeutic tool for the treatment of cancer, was investigated. Citric acid-iron oxide nanoparticles exhibited the highest heating performance, with an intrinsic loss power of 4.1 nHm2kg-1, which is 30% better than the best commercially available equivalent. Finally, their potential to treat near-surface or accessible tumours was tested in vitro on a human melanoma DX3 cell model. The results showed a controllable cell death via selective apoptosis or necrosis depending on the field and frequency applied. Time-lapse fluorescent microscopy experiments allowed the first direct observation of magnetic hyperthermia in adherent cells, where total-population cell death by apoptosis was observed.
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Kiiashko, Artur. "Amélioration des propriétés rhéologiques et à jeune âge des laitiers alcali-activés au carbonate de sodium." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN033.
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Aujourd'hui, les problèmes environnementaux sont plus graves que jamais. Des mesures urgentes devraient être prises dans tous les domaines de l'activité humaine, y compris la construction. L'un des principaux contributeurs à l'impact négatif de cette industrie sur l'environnement est la fabrication du ciment Portland ordinaire (OPC) nécessaire à la production de béton et d’autres matériaux cimentaire. Malgré son importance, il présente un inconvénient important: sa production est accompagnée par de grandes quantités de gaz à effet de serre. Ils représentent 5 à 8% des émissions mondiales totales de CO2. Des matériaux cimentaires plus écologiques sont maintenant nécessaires.Des réductions significatives de l’impact sur l’environnement ne peuvent être obtenues que par l’utilisation de liants de nouvelle génération dont la fabrication ne nécessite pas beaucoup de processus et de traitements supplémentaires. L'une d'elles consiste à utiliser des déchets industriels comme liants (différentes laitiers, cendres volantes, cendres de biomasse, etc.). De cette manière, il y a non seulement une réduction de l'impact de processus tels que l'extraction minière ou la calcination, mais également le recyclage des déchets (un principe de l'économie circulaire).Une possibilité consiste à utiliser du laitier de haut fourneau (GGBS) comme base pour ce ciment de nouvelle génération. En raison de sa réactivité relativement faible avec l'eau, des suppléments (également appelés activateurs) doivent être utilisés pour favoriser le processus d'hydratation. Le carbonate de sodium (Na2CO3) est l’un des activateurs les plus prometteurs et en même temps les moins étudiés. Un tel ciment alkali-activé présente des propriétés mécaniques et de durabilité élevées, ainsi qu'une empreinte CO2 très faible. Parmi les principaux problèmes qui entravent son utilisation à l'échelle industrielle, on peut mentionner une évolution de la résistance lente à jeune âge et de rhéologie médiocre.L'objectif de la présente thèse est de développer une nouvelle conception du liant à base de laitier activé par Na2CO3, qui répondrait à toutes les exigences modernes du secteur de la construction, en particulier les propriétés rhéologiques et le développement de la résistance à jeune âge. Ce liant doit toujours répondre à au moins trois critères principaux: faible impact environnemental, faibles risques de danger dans les applications sur le terrain et être économiquement compétitif à l'échelle industrielle.Dans le présent travail, l’influence de différents paramètres tels que le rapport eau/liant, la concentration de Na2CO3, la finesse du laitier et les conditions de durcissement sur les propriétés du mélange à jeune âge et à long terme a été étudiée. Sur la base des résultats du processus d’hydratation, les additifs à base de phosphonate qui permettent de contrôler efficacement la rhéologie de tels liants ont été testé avec succès. Ils permettent non seulement de contrôler le temps de prise, mais fournissent également un effet plastifiant.En ce qui concerne l’amélioration des propriétés de résistance au jeune âge, différentes méthodes ont été utilisées. L’utilisation d’un traitement thermique ou d’une augmentation de la finesse du GGBS s’est avérée efficace. L’exploration des causes d’une longue période d’induction a montré que l’accélération pouvait également être obtenue par l’ajout d’une source de calcium à cinétique de dissolution contrôlée. En conséquence, le liant est devenu plus réactif et plus robuste à certains facteurs (concentration d’activateur, rapport eau/liant, conditions de durcissement, etc.). Pour compenser l'empreinte carbone supplémentaire de la source de calcium ajoutée, le liant a été dilué avec succès par le calcaire sans aucune dégradation des propriétés à un certain pourcentage de dilutionToday, environmental problems are more acute than ever. Urgent measures should be taken in all spheres of human activity including construction and civil engineering. One of the major contributors of negative environmental impacts from this industry is the manufacturing of ordinary Portland cement (OPC) required for concrete and other cementitious materials production. Although its importance to economical development, it has a significant drawback - its production is accompanied by the emission of large quantities of greenhouse gases. They account for 5-8% of total world CO2 emissions. More environmentally friendly cementitious materials are now required.Significant reductions of the environmental impact can be achieved only through the use of new-generation binders whose manufacture does not require a lot of additional processes and treatments. One route is through the use of industrial wastes as binders (different slags, fly ash, biomass bottom ash, etc.). In this way there is not only a reduction in the impact of processes such as mining or calcination, but also the recycling of waste materials (circular economy principle).One possibility is to use ground granulated blast furnace slag (GGBS) as the basis for such a new generation cement. Due to its rather low reactivity with water, additional supplements (also called activators) should be used to promote the hydration process. One of the most promising, and at the same time least studied, activators is sodium carbonate (Na2CO3). Such alkali-activated cements present high mechanical and durability properties, as well as a very low CO2 footprint. Among the main problems hindering its industrial scale adoption are their poor rheology and too slow strength gain within the first days of hardening.The objective of the present thesis is to develop a new binder based on Na2CO3 activated GGBS that would meet all the modern requirements of the construction industry, in particular regarding the rheological properties and early age strength development. In addition this binder should always respond to at least three main criteria: low environmental impact, low health and safety concerns in field applications, and be economically competitive at industrial scale.In the present work, the influence of different parameters like water/binder ratio, Na2CO3 concentration, slag fineness and curing conditions on both early age and long term properties of the mixture were studied. Based on the results of the hydration process analysis, phosphonate based additives that allow for the effective control of the rheology of such binders were successfully tested. They not only allow control over the setting time, but also provide a plasticizing effect.Regarding the improvement of early age strength properties, various methods have been used. The use of heat treatment or an increase of GGBS fineness turned out to be efficient. Exploring the causes of the long induction period has shown that acceleration can also be achieved by the addition of a calcium source with controlled dissolution kinetics. As a result, the binder became more reactive and robust against certain factors (activator concentration, Water/Binder ratio, curing conditions, etc.). To compensate for the additional carbon footprint from the added calcium source, the binder was successfully diluted by limestone without any degradation of the properties below some dilution percentages
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Chandra, Yusup. "Alkaline pulping deadload reduction studies in chemical recovery system /." Thesis, Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-11162004-132752/unrestricted/Chandra%5FYusup%5F200412%5Fmast.pdf.
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Thesis (M.S.)--Chemical Engineering, Georgia Institute of Technology, 2005.Empie, Jeff, Committee Chair ; Banerjee, Sujit, Committee Member ; Deng, Yulin, Committee Member. Includes bibliographical references.
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Tong, Tianjian. "Co-effects of calcium carbonate and sodium bisulfite modification on improving water resistance of soy protein adhesives." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/14196.
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Master of ScienceDepartment of Grain Science & Industry
Xiuzhi Susan Sun
Bio-based protein adhesives derived from renewable resources, especially soy protein are becoming more significant due to the concerns about environment and health related issues and the limit of petroleum recourses. However, the relatively poor water resistance of soy-based protein adhesives limits its wide applications. The goal of this study was to improve the water resistance performance of soy-based protein adhesives by chemical modification. The specific objectives are 1) to modify soy protein with calcium carbonate (CaCO[subscript]3) and sodium bisulfite (NaHSO[subscript]3) as the denaturing agents; 2) to investigate the effects of calcium carbonate (CaCO[subscript]3) concentrations, curing time and curing temperatures on adhesion performance of the modified soy-based protein adhesives. In this study, the co-effects of NaHSO[subscript]3 and CaCO[subscript]3 on adhesion properties of soy protein adhesives were investigated. NaHSO[subscript]3 was added to soy flour slurry at constant concentration 6g/L, while concentration of CaCO[subscript]3 was chosen in the range of 0 to 23g/L. Soy protein adhesives modified with 4g/L and 16g/L CaCO[subscript]3 were selected to characterize the adhesion performance on 3 ply yellow pine plywood using the Response Surface Method (RSM). The effects of curing temperature and curing time on the adhesion properties were also studied. The major findings are 1) 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 modified soy protein adhesives (MSPA) had better adhesion performance (both dry and wet) than 16g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA; 2) Higher temperature (170°C) resulted in higher wet shear adhesion strengths; 3) Longer hot press time had positive impact on wet adhesion shear strength; and 4) 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA showed better adhesion shear strength after 2 weeks storage than 16g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA. In general, 4g/L CaCO[subscript]3, 6g/L NaHSO[subscript]3 MSPA, under longer hot press time and higher temperature would lead to a better adhesion performance.
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Beau, Daniel-Louis. "Action du dioxyde de carbone et des granulats calcaires sur les aluminates de calcium hydratés à l'équilibre de solubilité : influence des ions sulfates, réaction du calcaire finement pulverisé avec le silicate de sodium en solution alcaline." Dijon, 1991. http://www.theses.fr/1991DIJOS001.
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La mise en équations des équilibres de solubilité des différents aluminates de calcium hydratés et du gel d'alumine permet de construire leurs courbes d'équilibre dans les domaines métastables du diagramme chaux-alumine-eau. La prise en compte de l'action du dioxyde de carbone atmosphérique oblige à établir un diagramme tri-dimensionnel. Les courbes d'équilibre de solubilité des différentes phases hydratées sont des courbes gauches, dont les projections sur le plan chaux-alumine sont facilement exploitables. Dans un système isolé du dioxyde de carbone atmosphérique, mais en présence de granulats calcaires, les équilibres de solubilité des hydrates, du monocarboaluminate et du carbonate de calcium sont représentés par des surfaces dont les interactions donnent les équilibres communs à deux des phases hydratées ou carbonatées. L'extension des calculs et du même type de diagramme au système chaux-alumine-eau-sulfate permet de délimiter les domaines de stabilité de l'ettringite et du monosulfoaluminate de calcium hydraté. On a étudié experimentalement et abordé par le calcul thermodynamique les possibilités de formation de silicate de calcium hydraté susceptible de faire prise par injection dans le sol d'une solution de silicate de soude alcalinisée et d'une suspension de carbonate de calcium. Les conditions favorables à cette formation ont été précisées.
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Diguet, Sylvain. "Contribution à l'étude de la déshydratation du carbonate de sodium monohydrate en lit fluidisé dense et mise en oeuvre en lit fluidisé circulant : étude expérimentale et modélisation." Toulouse, INPT, 1996. http://www.theses.fr/1996INPT022G.
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La deshydratation du carbonate de sodium monohydrate est l'une des etapes clefs dans la fabrication d'un produit mineral de premier rang, le carbonate de soude dense. Cette reaction gaz-solide est souvent realisee dans des fours rotatifs ou des fours tunnels. Or, ce type de reacteur est tres mal adapte pour les reactions rapides controlees par les transferts externes de matiere et de chaleur a cause de la difficulte a controler l'atmosphere environnant les grains. Cette derniere a une influence, non seulement sur le rendement energetique de l'operation, mais egalement sur la morphologie finale du produit solide. Les reacteurs a lit fluidise et leurs derives semblent mieux adaptes pour les reactions gaz-solide rapides puisqu'ils permettent un traitement uniforme des solides et ce, grace a un controle rigoureux et aise de l'atmosphere environnant le grain. Ce travail est le fruit d'une collaboration tripartite: la societe rhone-poulenc, l'universite de bradford et l'e. N. S. I. G. C de toulouse dont les objectifs sont les suivants: acquisition des donnees cinetiques en thermobalance et en lit fluidise discontinu etude hydrodynamique des lits fluidises circulants mise en uvre et modelisation de la reaction en lit fluidise circulant. L'ensemble des resultats obtenus a montre que le lit fluidise circulant peut etre envisage comme une technique bien adaptee pour la deshydratation du carbonate de sodium monohydrate. Elle peut etre consideree comme une alternative d'avenir aux technologies traditionnelles utilisees actuellement pour les reactions gaz-solide rapides
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Gao, Jiong. "UV/Sodium Percarbonate for Treatment of Bisphenol A in Water." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin161710940946631.
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Nasir, Subriyer. "Membrane performance and build-up of solute during small scale reverse osmosis operation." Thesis, Curtin University, 2007. http://hdl.handle.net/20.500.11937/590.
Full textAbstract:
Reverse Osmosis (RO) is widely accepted as an alternative method to produce freshwater from different feed water sources. This technology competitively substitutes the thermal processes in the near future because of several advantages particularly in energy saving. The success of RO operation will, however, depends largely on the overall membrane performance. Deposit or build-up of solute is one of the main reasons for membrane operation failure. Build-up of solute or deposit which is known as fouling and scaling will decrease the permeate flux and increase the energy consumption in particular after prolonged operation of RO. The thesis presents the experimental results obtained in a small-scale RO system. The aim of this study is to investigate the effect of sodium chloride and calcium carbonate on the membrane performance and subsequent build-up of solute on the membrane surface. The experiments were carried out in a small-scale of RO (2 m3/day capacity) with spiral wound membrane using simulated feed water, secondary effluent, and groundwater samples. The parameters chosen for the experiments are applied pressure (1250-4750 kPa), and concentration of sodium chloride (l00-5000 mg/L) and calcium carbonate (50-100 mg/L).The results from feedwater runs indicated that initial sodium chloride and calcium carbonate in feed water and applied pressure affects the overall membrane performance. However, there is no significant effect on membrane performance for sodium chloride with concentration below 1200 mg/L and applied pressure lower than 2250 kPa. Applied pressure appears to have an impact on build-up of sodium and calcium on the membrane surface for pressures greater than 2750 kPa. For typical small-scale RO system used in this experiment, build-up of calcium will slightly decrease with given pressure caused by the characteristic of membrane that easily removes the divalent ions. The osmotic pressure of solution also strongly affects the permeate flow rate in particular for relatively higher sodium concentration (> 2500 mg/L). As a consequence of higher osmotic pressure, zero permeate flux is achieved when sodium chloride concentration was greater than 5000 mg/L and applied pressure lower than 1750 kPa. Results also indicated that fouling might pose a potential problem in small-scale RO operation. In order to investigate the membrane performance, experiments with secondary effluent samples were also performed. Results indicated that water recovery percentages and permeate flux also linearly increase with applied pressure. However, effectiveness of membrane decreases less than 98% otherwise build-up of solute tends to increase. It is suggested that lower values of the water recovery percentage (WRP) and permeate flux (Jw) are caused by the characteristic of secondary effluent that have high-suspended solids, organic carbon, and minerals. Further, the membrane performance also examined with ground water as feed water sample.Results showed that both water recovery percentage and permeate flux linearly increased with operating pressure. However, intensive pretreatment are required as a result of higher concentration of humic acid and iron in raw feed. Percentages of ion rejection for sodium and calcium are greater than 98 and 99% respectively. The high ion rejections are mainly due to the characteristics of groundwater with low TDS and EC. Sodium and calcium build-up in a small-scale RO system considered appears to be affected by the applied pressure. Build-up of solute in small-scale of RO system has been predicted using the empirical model proposed in this work. Two ions namely sodium and calcium in feed water considered as predominant ions responsible for fouling and scaling on the membrane surface. Four main parameters namely, applied pressure (P), permeate flux (Jw), membrane resistance (Rm), and feed concentration (Cf) are considered which strongly affect the overall membrane performance. The empirical correlations derived from experimental observation among these parameters can be expressed as follows: In Md NaCI = O. 77 In P + 0.67 In Jw + 0.19 In Rm + 0.171n Cf In Md CaCO3= 0.96 In P + 0.75 In Jw + 0.2 In Rm - 0.07 In CfThe empirical models proposed in this thesis may be useful for predicting the buildup of solute on the membrane surfaces. In the present work, an attempt has been made to estimate the energy consumption and unit cost for desalting of different feed water samples in a small-scale RO system. In RO plants, unit cost of water production from feed water is primarily governed by the energy required for pumping raw water. Estimates of specific energy consumption (SEC) for desalting of sodium chloride, combined sodium and calcium carbonate solutions were found to be in the range of 0.79 - 3.21 and 0.81 - 3.22 kwh/m3 respectively. For groundwater and secondary effluent, they are estimated to 0.63 - 1.71 and 0.79 - 2.02 kWh/m3 respectively. Moreover, energy consumption for different feed water samples was used to estimate the unit cost for water production. Estimation of unit costs for combined sodium chloride and calcium carbonate solution, groundwater, and secondary effluent runs are $2.06 - 3.22, $1.98 - 2.57 and $1.56- 2.66 respectively. In this work, unit cost is still higher due to greater energy consumption .by the pumping system which is required in a small-scale RO operation. Based on the experimental results, it appears that the characteristics of feed water samples affect the membrane performance and their effects must be taken into account in the design of RO units so as to reduce the unit cost for water production.The findings from the present experimental and modelling work are of practical significance in not only providing the knowledge base in the area of desalination but also paves the way for developing tools for the prediction of build-up of solutes on membrane surface in full scale reverse osmosis operations.
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Verrill, Christopher Lee. "Inorganic aerosol formation during black liquor drop combustion." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/5793.
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St-Laurent, Anne-Marie. "Evaluation of methods and effects of feeding sodium bicarbonate in conventional diets to dairy cows in early lactation and effects of feeding buffers prepartum on performance in early lactation." Thesis, McGill University, 1986. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66132.
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Chalamuri, Shanmuka Harish. "The Evaluation of the Effect of Anionic and Cationic Surfactants on the Hindered Settling of Light Calcium Carbonate Suspensions." University of Toledo Health Science Campus / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=mco1418602604.
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Zethelius, Thea. "Natriumkarbonat som alternativ alkalikälla till natriumhydroxid : Impregnering och blekning av kemitermomekanisk massa." Thesis, Karlstads universitet, Institutionen för ingenjörs- och kemivetenskaper (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-72437.
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Arbetet handlade om att ta reda på om det går att byta ut natriumhydroxid mot natriumkarbonat som alkalikälla på CTMP-linjen, och gjordes på uppdrag av Stora Enso Skoghalls bruk. De områdena som studerades var impregnering och blekning av CTMP (kemitermomekanisk pappersmassa) samt hantering av natriumkarbonatlösning. Natriumkarbonatens löslighet vid olika temperaturer verifierades, blekning av CTMP med natriumkarbonat och natriumhydroxid utfördes, titrering av natriumhydroxid och natriumkarbonat mot natriumbisulfitlösning och en enklare laborationsimpregnering gjordes. Även aspekten av utrustning, kostnader och eventuell utfällning av kalciumkarbonat studerades. Resultaten visade att det krävs mer natriumkarbonat för att ersätta natriumhydroxid än vad man trott och att det totalt sett blir dyrare. Det finns dock en möjlighet att andra delar av bruket kan utföra bytet av alkali och gå med större vinst än vad CTMP-linjen går med förlust. Försöken visade även på temperaturökning vid tillredning av natriumkarbonatlösningen, utfällning av kristallsoda och behov av att den befintliga utrustningen kompletteras utifrån rekommendationer från kemikalieleverantören. Tidigare studier visade på eventuella försämringar av papperskvaliteten när natriumkarbonat används vid blekning av CTMP. Trots att natriumkarbonat är ett billigare alternativ till natriumhydroxid, och att det teoretiskt sett skulle fungera bra som en utbrytare, är det mycket som man behöver ta hänsyn till vad gäller natriumkarbonat och det krävs eftertanke för att saker ska görs på rätt sätt. Utifrån resultaten kan man dra slutsatsen att det inte ser ut som en bra ide att utföra bytet.The objective of this project was to see if it is possible to replace sodium hydroxide with sodium carbonate as an alkali source on the CTMP line, and it was done on behalf of the Stora Enso Skoghall Mill. The areas that were studied were the impregnation and bleaching of CTMP and also the handling of sodium carbonate solution. The solubility of sodium carbonate at various temperatures was confirmed, bleaching of CTMP with sodium hydroxide and sodium carbonate, titration of the sodium hydroxide and sodium carbonate against sodium bisulfite solution and a simpler laboratory impregnation was performed. Aspects of equipment, costs and the possibility of precipitation of calcium carbonate were also studied. The results indicate that more sodium carbonate is needed than one thought for the substitution to be possible, and that it also becomes more expensive. There is a possibility that other parts of the mill can perform the replacement of alkali and go with greater profit than the CTMP line goes with loss. Experiments also showed an increase in temperature when preparing the sodium carbonate solution, precipitation of natron and the need for the existing equipment to be supplemented on the basis of recommendations from the chemical supplier. Previous studies showed possible deterioration of the paper quality when bleaching CTMP with sodium carbonate. Although sodium carbonate is a cheaper alternative to sodium hydroxide, and that it would theoretically work well as a substitute, it is much that one has to take into consideration in terms of using sodium carbonate and it is necessary to think things through before usage, so that things can be done properly. Based on the results, it is shown that the swap of alkali will be suboptimal.
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Samperisi, Laura. "Study of the effectiveness of crystal growth modifiers in the prevention of damage due to crystallization of sodium carbonates in stone artworks." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14399/.
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The disintegration of stone materials used in sculpture and architecture due to the crystallization of salts is capable of irreparably damaging artistic objects and historic buildings. A number of phosphonates and carboxylates were tested here as potential crystallization modifiers for sodium carbonate crystallization. Precipitated phases during crystallization induced either by cooling or by evaporation tests were nahcolite (NaHCO3), natron (Na2CO3∙10H2O) and thermonatrite (Na2CO3∙H2O), identified using X-ray diffraction. By using the thermodynamic code PHREEQC and the calculation of the nucleation rate it was demonstrated that nahcolite had to be first phase formed during both tests. The formation of the other phases depended on the experimental conditions under which the two tests were conducted. Nahcolite nucleation is strongly inhibited in the presence of sodium citrate tribasic dihydrate (CA), polyacrylic acid 2100MW (PA) and etidronic acid (HEDP), when the additives are dosed at appropriate concentrations and the pH range of the resulting solution is about 8. Electrostatic attraction generated between the deprotonated organic additives and the cations present in solution appears to be the principal mechanism of additive-nahcolite interaction. Salt weathering tests, in addition to mercury intrusion porosimetry tests allowed to quantify the damage induced by such salts. FESEM observation of both salts grown on calcite single crystals and in limestone blocks subjected to salt crystallization tests allowed to identify the effect of these additives on crystal growth and development. The results show that PA seems to be the best inhibitor, while CA and HEDP, which show similar behaviors, are slightly less effective. The use of such effective crystallization inhibitors may lead to more efficient preventive conservation of ornamental stone affected by crystallization damage due to formation of sodium carbonate crystals.
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BLENGINO, JEAN-MICHEL. "Contribution a l'etude de la corrosion sous contrainte du fer et des aciers doux en milieu carbonate-hydrogenocarbonate de sodium." Paris 6, 1993. http://www.theses.fr/1993PA066671.
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La presente etude tente d'apporter quelques elements nouveaux a la connaissance de la fissuration sous contrainte du fer et des aciers doux assistee par un environnement riche en ions hydrogenocarbonate, phenomene aujourd'hui unanimement reconnu comme cause de nombreux cas de rupture de canalisations de transport d'hydrocarbures ou de gaz soumises a une protection cathodique. L'etude des phenomenes electrochimiques regissant la dissolution du fer dans le domaine de potentiel correspondant a la transition activite-passivite (zone sensible vis-a-vis de la corrosion sous contrainte), la caracterisation ex-situ des depots de surface (notamment l'analyse compositionnelle qualitative et quantitative par spectroscopie infrarouge, la mesure de la conduction electrique a l'interieur des couches) permettent d'etablir une correlation entre la nature et l'abondance des divers produits de corrosion d'une part et la susceptibilite du systeme au risque d'endommagement considere ici d'autre part. Les hydroxycarbonates mixtes de fer ii et fer iii a 25 et 50c, le carbonate de fer feco#3 a 80c, se revelent etre les constituants majoritaires des surfaces dans les conditions ou le metal fissure. Une critique d'un modele propose dans la litterature, selon lequel la susceptibilite a la corrosion sous contrainte du systeme est correlee a la constante de temps de la boucle bf de l'admittance electrochimique, est suggeree. L'etude de la fissuration sous contrainte mecanique, entreprise dans le cadre d'essais de traction a vitesse lente sur eprouvettes lisses maintenues a potentiel controle, nous permet de proposer une modelisation des phenomenes electrochimiques mis en jeu au cours de l'essai mecanique, verifiee par le biais d'arrets intermittents de la traction. L'effet de l'etat de contraintes initial est egalement pris en compte. Les mesures d'impedance electrochimique realisees en cours d'essai de traction ne permettent apparemment pas de mettre en evidence d'evolution significative du diagramme en fonction du niveau d'avancement de la fissuration
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Joseph, Manjusha. "A study of carbonate-rich brines from Sua Pan to characterize organic contaminants in the soda ash process." Thesis, Rhodes University, 2001. http://hdl.handle.net/10962/d1004091.
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Botswana Ash (Pty) Ltd which is situated in Sua Pan, north east Bostwana, is one of Africa's largest suppliers of salt and soda ash. For a number of years, the company has been experiencing problems which have resulted in the final soda ash product being contaminated and discoloured. The problems experienced at Sua Pan have been reported also to occur in other salt works all over the world. It has been suggested that contamination in many salt works could be possibly be due to the microbial activity by halophilic algae and bacteria that grow in the solar ponds. This study was undertaken to investigate the nature of the contaminating organic compounds present in the brine, to identify the compounds, and to establish how these components vary during the various stages of the soda ash processing. For this study, two sets of brine samples were used; the first set was collected before the summer rains and the second set was collected after the summer rains. Solid bicarbonate and soda ash samples were also used. Extractions, desalting, UV and HPLC analysis and oxidative biotransformations using four enzymes, were used for developing profiles and characterizing the brine components. From these studies, we were able to confirm that the components of the brine are organic in nature. A thorough study of one of the compounds isolated,from solid bicarbonate and soda ash was conducted using UV, HPLC, IR, NMR, HPLC-MS, GC-MS and TLC. The results of these analyses, show that the. isolated compound was benzyl butyl phthalate which is generally regarded to be humic in nature. This compound was found to be present in all the brine samples collected after the summer rains including the well brine, suggesting this compound occurs naturally and is not formed during the processing.
31
Feng, Xu. "Interaction of Na, O2, CO2 and water on MnO(100): Modeling a complex mixed oxide system for thermochemical water splitting." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/77378.
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A catalytic route to hydrogen production via thermochemical water splitting is highly desirable because it directly converts thermal energy into stored chemical energy in the form of hydrogen and oxygen. Recently, the Davis group at Caltech reported an innovative low-temperature (max 850C) catalytic cycle for thermochemical water splitting based on sodium and manganese oxides (Xu, Bhawe and Davis, PNAS, 2012). The key steps are thought to be hydrogen evolution from a Na2CO3/MnO mixture, and oxygen evolution by thermal reduction of solids formed by Na+ extraction from NaMnO2. Our work is aimed at understanding the fundamental chemical processes involved in the catalytic cycle, especially the hydrogen evolution from water. In this project, efforts are made to understand the interactions between the key components (Na, O2, CO2, and water) in the hydrogen evolution steps on a well-defined MnO(100) single crystal surface, utilizing x-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and temperature programmed desorption (TPD).
While some of the behavior of the catalytic system is observed with the model system developed in this work, hydrogen is only produced from water in the presence of metallic sodium, in contrast to the proposal of Xu et al. that water splitting occurs from the reaction of water with a mixture of Na2CO3 and MnO. These differences are discussed in light of the different operating conditions for the catalytic system and the surface science model developed in this work.Ph. D.
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Nasir, Subriyer. "Membrane performance and build-up of solute during small scale reverse osmosis operation." Curtin University of Technology, Department of Chemical Engineering, 2007. http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=17394.
Full textAbstract:
Reverse Osmosis (RO) is widely accepted as an alternative method to produce freshwater from different feed water sources. This technology competitively substitutes the thermal processes in the near future because of several advantages particularly in energy saving. The success of RO operation will, however, depends largely on the overall membrane performance. Deposit or build-up of solute is one of the main reasons for membrane operation failure. Build-up of solute or deposit which is known as fouling and scaling will decrease the permeate flux and increase the energy consumption in particular after prolonged operation of RO. The thesis presents the experimental results obtained in a small-scale RO system. The aim of this study is to investigate the effect of sodium chloride and calcium carbonate on the membrane performance and subsequent build-up of solute on the membrane surface. The experiments were carried out in a small-scale of RO (2 m3/day capacity) with spiral wound membrane using simulated feed water, secondary effluent, and groundwater samples. The parameters chosen for the experiments are applied pressure (1250-4750 kPa), and concentration of sodium chloride (l00-5000 mg/L) and calcium carbonate (50-100 mg/L).The results from feedwater runs indicated that initial sodium chloride and calcium carbonate in feed water and applied pressure affects the overall membrane performance. However, there is no significant effect on membrane performance for sodium chloride with concentration below 1200 mg/L and applied pressure lower than 2250 kPa. Applied pressure appears to have an impact on build-up of sodium and calcium on the membrane surface for pressures greater than 2750 kPa. For typical small-scale RO system used in this experiment, build-up of calcium will slightly decrease with given pressure caused by the characteristic of membrane that easily removes the divalent ions. The osmotic pressure of solution also strongly affects the permeate flow rate in particular for relatively higher sodium concentration (> 2500 mg/L). As a consequence of higher osmotic pressure, zero permeate flux is achieved when sodium chloride concentration was greater than 5000 mg/L and applied pressure lower than 1750 kPa. Results also indicated that fouling might pose a potential problem in small-scale RO operation. In order to investigate the membrane performance, experiments with secondary effluent samples were also performed. Results indicated that water recovery percentages and permeate flux also linearly increase with applied pressure. However, effectiveness of membrane decreases less than 98% otherwise build-up of solute tends to increase. It is suggested that lower values of the water recovery percentage (WRP) and permeate flux (Jw) are caused by the characteristic of secondary effluent that have high-suspended solids, organic carbon, and minerals. Further, the membrane performance also examined with ground water as feed water sample.
Results showed that both water recovery percentage and permeate flux linearly increased with operating pressure. However, intensive pretreatment are required as a result of higher concentration of humic acid and iron in raw feed. Percentages of ion rejection for sodium and calcium are greater than 98 and 99% respectively. The high ion rejections are mainly due to the characteristics of groundwater with low TDS and EC. Sodium and calcium build-up in a small-scale RO system considered appears to be affected by the applied pressure. Build-up of solute in small-scale of RO system has been predicted using the empirical model proposed in this work. Two ions namely sodium and calcium in feed water considered as predominant ions responsible for fouling and scaling on the membrane surface. Four main parameters namely, applied pressure (P), permeate flux (Jw), membrane resistance (Rm), and feed concentration (Cf) are considered which strongly affect the overall membrane performance. The empirical correlations derived from experimental observation among these parameters can be expressed as follows: In Md NaCI = O. 77 In P + 0.67 In Jw + 0.19 In Rm + 0.171n Cf In Md CaCO3= 0.96 In P + 0.75 In Jw + 0.2 In Rm - 0.07 In Cf
The empirical models proposed in this thesis may be useful for predicting the buildup of solute on the membrane surfaces. In the present work, an attempt has been made to estimate the energy consumption and unit cost for desalting of different feed water samples in a small-scale RO system. In RO plants, unit cost of water production from feed water is primarily governed by the energy required for pumping raw water. Estimates of specific energy consumption (SEC) for desalting of sodium chloride, combined sodium and calcium carbonate solutions were found to be in the range of 0.79 - 3.21 and 0.81 - 3.22 kwh/m3 respectively. For groundwater and secondary effluent, they are estimated to 0.63 - 1.71 and 0.79 - 2.02 kWh/m3 respectively. Moreover, energy consumption for different feed water samples was used to estimate the unit cost for water production. Estimation of unit costs for combined sodium chloride and calcium carbonate solution, groundwater, and secondary effluent runs are $2.06 - 3.22, $1.98 - 2.57 and $1.56- 2.66 respectively. In this work, unit cost is still higher due to greater energy consumption .by the pumping system which is required in a small-scale RO operation. Based on the experimental results, it appears that the characteristics of feed water samples affect the membrane performance and their effects must be taken into account in the design of RO units so as to reduce the unit cost for water production.
The findings from the present experimental and modelling work are of practical significance in not only providing the knowledge base in the area of desalination but also paves the way for developing tools for the prediction of build-up of solutes on membrane surface in full scale reverse osmosis operations.
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Nobel, Pujol-Lesueur Véronique. "Etude du mécanisme d'action du monofluorophosphate de sodium comme inhibiteur de la corrosion des armatures metalliques dans le beton." Paris 6, 2004. http://www.theses.fr/2004PA066251.
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Marins, Gabriel de. "Caracterização do licor negro de eucalipto para avaliação do potencial de incrustação em evaporadores." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266706.
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Orientador: José Vicente Hallak d'AngeloDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-21T11:05:01Z (GMT). No. of bitstreams: 1 Marins_Gabrielde_M.pdf: 4193921 bytes, checksum: e80672b42613eddad46d14b2c94e31c8 (MD5) Previous issue date: 2012
Resumo: No processo Kraft para produção de papel e celulose, os cavacos de madeira são cozidos em um digestor com uma solução aquosa denominada licor branco, constituída de hidróxido de sódio (NaOH) e sulfeto de sódio (Na2S). Durante o cozimento uma pasta fibrosa é produzida. Esta pasta é filtrada e segue para o branqueamento. O produto filtrado chama-se licor negro, devido à mudança da sua cor nesta etapa. O licor negro possui aproximadamente 15 % de sólidos em massa. Ele é bombeado para a unidade de recuperação, na qual ele será concentrado em evaporadores de múltiplosefeitos até 75 % de sólidos em massa. Em seguida, ele é bombeado para uma caldeira onde é queimado, para recuperar os sais inorgânicos e, principalmente, fornecer calor para geração de calor. Durante a evaporação do licor negro, quando a porcentagem em sólidos ultrapassa 50 %, ocorre a precipitação de sais inorgânicos. Estes sais se depositam nas superfícies de troca térmica dos evaporadores diminuindo sua eficiência e causando prejuízos à indústria. Os principais sais que causam este problema são o carbonato de sódio (Na2CO3) e o sulfato de sódio (Na2SO4). O objetivo do presente trabalho foi testar e validar um método experimental para a determinação da quantidade de Na2CO3 presente em amostras industriais de licor negro. Além disso, também foram analisadas algumas propriedades físico-químicas do licor negro, como massa específica, teor de sólidos e viscosidade. Com os resultados obtidos, tentou-se obter uma correlação entre o teor de carbonato de sódio e as demais propriedades do licor que foram determinadas. Os resultados das análises das características físico-químicas demonstraram coerência e boa reprodutibilidade, porém, os resultados das análises de teor de carbonato de sódio não foram satisfatórios e mostraram que a técnica deve ser aperfeiçoada
Abstract: In the Kraft process for pulp and paper production, wood chips are cooked in a digester with an aqueous solution named white liquor, consisted by sodium hydroxide (NaOH) and sodium sulfide (Na2S). During this cooking process, wood chips are transformed generating a fibrous paste and a liquid solution. This paste is filtered and separated from the liquid solution, named black liquor due to its color. The paste goes to the bleaching stage to produce cellulose. Black liquor contains inorganic and organic (mainly lignin) compounds from wood. Initially this black liquor contains approximately 15 mass/% of solids and is sent to the recovery unit to have this concentration raised to approximately 75 mass/% to be burned in a recovery boiler in order to generate power and recover inorganic reactants, recycling them to the process. The concentration process of black liquor occurs in a multiple effect evaporators unit. During this process, when the concentration of solids exceeds 50%, the precipitation of inorganic salts (mainly Na2CO3 and Na2SO4) begins. These salts are deposited in the heat transfer surfaces of the evaporator tubes, reducing their efficiency, leading to a reduction in the production capacity. The scope of this work was testing and validate an experimental method to estimate the content of Na2CO3 present in industrial black liquor samples. Moreover, some black liquor's physical-chemical properties as density, solids content and viscosity were also analyzed. An attempt to develop a predictive model to evaluate sodium carbonate content from the other properties was made. The results obtained for physical-chemical properties have shown a good consistency. However, the results of sodium carbonate analyses were not satisfactory, showing that the technique must be improved
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestre em Engenharia Química
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Bayuadri, Cosmas. "Stability of sodium sulfate dicarbonate (~2Na₂CO₃• Na₂SO₄) crystals." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11507.
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Research on salts species formed by evaporation of aqueous solution of Na2 in the early 1930s. The thermodynamic, crystallographic and many other physical and chemical properties of most of the species formed from this solution has been known for decades. However, there was no complete information or reliable data to confirm the existence of a unique double salt that is rich in sodium carbonate, up until five years ago when a research identified the double salt (~2Na ₂ CO ₃ • Na ₂ SO ₄) from the ternary system Na₂CO ₃Na₂SO ₄ H₂O. Crystallization of this double salt so called sodium sulfate dicarbonate (~2Na ₂ CO ₃ • Na ₂ SO ₄) is known to be a primary contributor to fouling heat transfer equipment in spent-liquor concentrators used in the pulp and paper industry. Therefore, understanding the conditions leading to formation of this double salt is crucial to the elimination or reduction of an industrial scaling problem. In this work, double salts were generated in a batch crystallizer at close to industrial process conditions. X-ray diffraction, calorimetry, and microscopic observation were used to investigate the stability of the salts to in-process aging, isolation and storage, and exposure to high temperature. The results show that care must be taken during sampling on evaporative crystallization. Two apparent crystal habits were detected in the formation of sodium sulfate dicarbonate; the favored habit may be determined by calcium ion impurities in the system. The results also verify that sodium sulfate dicarbonate exists as a unique phase in this system and that remains stable at process conditions of 115-200℃
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Sellami, Jawhar. "Conception, mise en œuvre, développement et modélisation de réacteurs de précipitation utilisant des lits fluidisés." Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL088N/document.
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L’objectif de ce travail est de concevoir, développer, mettre en œuvre et optimiser une technologie continue permettant une bonne maîtrise des réactions de précipitation, processus chimique rapide donnant naissance à une phase solide. Ce précipiteur est un réacteur multifonctionnel à lit fluidisé qui n’a pas connu le même essor que les cristallisoirs à lit fluidisé. Deux approches expérimentales ont été adoptées : (1) l’étude des phénomènes de mélange des réactifs et (2) l’étude de l’influence des conditions opératoires sur la précipitation d’un produit modèle. Le produit modèle choisi pour cette étude est la calcite, le polymorphe le plus stable du carbonate de calcium qui possède trois polymorphes : la vaterite, l’aragonite et la calcite. Cette dernière est obtenue via la réaction de précipitation entre les solutions de chlorure de calcium et de carbonate de sodium à une température de 20° C et en présence d’un agent complexant (citrate de sodium) pour orienter la forme cristalline recherchée. Une étude cinétique a été menée pour la détermination des cinétiques de nucléation et de croissance cristalline de la calcite en milieu citrate. Le réacteur à lit fluidisé, de volume de 10 L, constitué de deux zones : cylindrique de fluidisation et de classification des particules et cylindro-conique de décantation, a été conçu au Laboratoire des Sciences du Génie Chimique. L’étude du mélange global, réalisée à l’aide de la réaction de décoloration acide-base et l’étude hydrodynamique, réalisée à l’aide de suspensions de microbilles, ont permis de développer et d’optimiser ce réacteur multifonctionnel. La faisabilité de la précipitation de la calcite en lit fluidisé a été ensuite vérifiée. Les expériences effectuées en présence d’une charge solide conséquente ont permis de diminuer la sursaturation et de favoriser la croissance cristalline. Le précipité obtenu présente une distribution de taille relativement étroite et la forme des particules obtenues est sensiblement sphérique. Enfin, des essais de modélisation du réacteur à lit fluidisé ont été entrepris pour réaliser des simulations à l’aide du code de calcul commercial FLUENTThe objective of this work is to conceive, develop, implement and to optimize a continuous technology allowing a good control of the precipitation reactions, fast chemical process, giving birth to a solid phase. This precipitor is a multipurpose engine with fluidized bed which did not make the same great strides like fluidized bed crystallizers. Two experimental approaches were adopted : (1) the study of the mixing phenomena of the reagents and (2) the study of the influence of the operating conditions on the precipitation of a model product. The model product selected for this study is the calcite, the polymorphic most stable phase of calcium carbonate which has three polymorphs: vaterite, aragonite and calcite. The latter is obtained by the precipitation reaction between the calcium chloride and sodium carbonate solutions at a temperature of 20° C and a complexing agent (sodium citrate) to have the required crystalline form. A kinetic study was undertaken for the determination of the nucleation and crystalline growth kinetics of calcite in citrate medium. The fluidized bed reactor, having a volume of 10 L, consisted of two zones: cylindrical for fluidization and classification of the particles and cylindro-conical for decantation, was conceived at the Chemical Engineering Science Laboratory (LSGC). The study of mixing phenomena, performed using the decoloration acid-base reaction and the hydrodynamic study, carried out using suspensions of glass microballs, made it possible to develop and optimize this multipurpose reactor. The feasibility of the precipitation of calcite in a fluidized bed was then checked. The experiments carried out in the presence of an important solid content made it possible to decrease supersaturation and to support the crystalline growth. The precipitate obtained presents a relatively narrow size distribution and the particle shape is appreciably spherical. Lastly, the modelling tests of the fluidized bed reactor were undertaken to carry out simulations using the FLUENT commercial computer code
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Woelffel, William. "Réactivité effective des mélanges vitrifiables granulaires silico-sodocalciques." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066598/document.
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L'objectif de cette thèse est d'étudier les transformations physico-chimiques lors de l'élaboration d'un verre à partir d'un mélange granulaire. Les mélanges vitrifiables industriel formant des verres de vitrage ou de conditionnement sont approchés par le système à trois oxydes SiO2-CaO-Na2O, apportés sous forme de sable, de calcaire et de carbonate de sodium. Cette simplification permet d'étudier le lien entre microstructrure de l'empilement granulaire et transformations pendant le chauffage. La variété des chemins réactionnels entre les grains de matières premières transmet en effet l'hétérogénéité du mélange au verre. Le système ternaire est décomposé en deux sous-systèmes. D'une part, les réactions entre le disilicate de sodium et 4 porteurs de calcium (CaCO3, CaO, CaSiO3, Ca2SiO4) révèlent la formation de couches d'espèces cristallines entre le grain calcique en cours de dissolution et le silicate fondu. D'autre part, la synthèse ex situ de carbonate mixte de calcium et de sodium est réalisée. Ce produit est analysé et caractérisé ; son apparition in situ dans un mélange ternaire est observée, et sa réaction avec la silice est étudiée. Dans un mélange vitrifiable silico-sodocalcique, la tomographie X in situ et post mortem montre l'importance de phénomènes transitoires de mouillage et de dégagement gazeux qui orientent les réactions chimiques. En particulier, un mécanisme local et de courte durée convertit une profondeur limitée des grains de calcaire en carbonate mixte. Enfin, l'homogénéité du verre obtenu à 1300°C est étudiée à l'aide d'une méthode de déconvolution de spectres Raman innovante, pour plusieurs granulométries et espèces porteuses de calciumThis thesis focuses on the physical and chemical transformations undergone by a granula glass batch during the glass making process. Industrial window or container glass batches are complex mixtures, that we approached by the ternary oxide system SiO2-CaO-Na2O. Industrial raw materials, namely silica sand, limestone and sodium carbonate, are used. This simplification makes it possible to study the coupling between the granular microstructure and the physical and chemical transformations during the heating. Indeed, the multiple possible reaction paths propagate the heterogeneity of the granular batch to the glass. To support our study of the ternary system, two sub-system are investigated. On one hand, reactions between sodium disilicate and 4 calcium-bearing species (CaCO3, CaO, CaSiO3, Ca2SiO4) show the formation of successive layers of crystalline intermediate species between the dissolving grains and the molten silicate. On the other hand, sodium calcium mixed carbonate is synthesized ex situ and characterized. Its formation in a ternary glass batch is observed in situ, and its reactivity with silica is studied. In a ternary soda-lime glass batch, X-ray in situ and ex situ microtomography reveals the significance of wetting and degassing phenomena in orienting the grains towards a reaction path. Conversion of a limited depth of limestone grains into mixed carbonate for a short time is notably witnessed. This mechanism is strongly dependent on the grains surrounding limestone particles. Finally, we use an innovative deconvolution procedure to measure the impact of granulometry and the nature of calcium-bearing raw materials on the final glass homogeneity
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Nunes, Shirlle Katia da Silva. "Tratamento de ?gua de produ??o de petr?leo visando o aproveitamento na obten??o de barrilha." Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15927.
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The petroleum production is associated to the produced water, which has dispersed and dissolved materials that damage not only the environment, but also the petroleum processing units. This study aims at the treatment of produced water focusing mainly on the removal of metals and oil and using this treated water as raw material for the production of sodium carbonate. Initially, it was addressed the removal of the following divalent metals: calcium, magnesium, barium, zinc, copper, iron, and cadmium. For this purpose, surfactants derived from vegetable oils, such as coconut oil, soybean oil, and sunflower oil, were used. The investigation showed that there is a stoichiometric relationship between the metals removed from the produced water and the surfactants used in the process of metals removal. It was also developed a model that correlates the hydrolysis constant of saponified coconut oil with the metal distribution between the resulting stages of the proposed process, flocs and aqueous phases, and relating the results with the pH of the medium. The correlation coefficient obtained was 0.963. Next, the process of producing washing soda (prefiro soda ahs ou sodium carbonate) started. The resulting water from the various treatment approaches from petroleum production water was used. During this stage of the research, it was observed that the surfactant assisted in the produced water treatment, by removing some metals and the dispersed oil entirety. The yield of sodium carbonate production was approximately 80%, and its purity was around 95%. It was also assessed, in the production of sodium carbonate, the influence of the type of reactor, using a continuous reactor and a batch reactor. These tests showed that the process with continuous reactor was not as efficient as the batch process. In general, it can be concluded that the production of sodium carbonate from water of oil production is a feasible process, rendering an effluent that causes a great environmental impact a raw material with large scale industrial use
A produ??o do petr?leo ? associada ? ?gua produzida, que apresenta materiais dispersos e dissolvidos que prejudicam n?o s? o meio ambiente, mas tamb?m, as unidades de processamento de petr?leo. Este trabalho objetiva o tratamento da ?gua de produ??o enfocando, principalmente, a remo??o de ?leo e de metais e a utiliza??o desta ?gua tratada como mat?ria-prima para produ??o de barrilha. Inicialmente, verificou-se a remo??o dos seguintes metais bivalentes: c?lcio, magn?sio, b?rio, zinco, cobre, ferro e o c?dmio. Utilizou-se para este fim tensoativos derivados de ?leos vegetais, tais como: ?leo de coco, ?leo de soja e ?leo de girassol. Verificou-se que existe uma rela??o estequiom?trica entre os metais removidos da ?gua de produ??o e os tensoativos utilizados no processo. Tamb?m, desenvolveu-se um modelo que relaciona a constante de hidr?lise do ?leo de coco saponificado com a distribui??o do metal entre as fases resultantes do processo proposto, fases floco e aquosa, relacionando os resultados com o pH do meio. Obteve-se um coeficiente de correla??o na ordem de 0,963. Em seguida, iniciou-se o processo de obten??o da barrilha. Utilizou-se a ?gua resultante das diversas correntes de tratamento da ?gua produzida. Nesta etapa do trabalho, observou-se que o tensoativo auxiliava no tratamento da ?gua de produ??o, removendo parte dos metais e a totalidade do petr?leo disperso. O rendimento da produ??o da barrilha foi da ordem de 80% e sua pureza ficou em torno de 95%. Avaliou-se, ainda, no processo de produ??o da barrilha, a influ?ncia do tipo de reator, utilizando-se um reator cont?nuo e um reator em batelada. Estes ensaios mostraram que o processo cont?nuo n?o foi t?o eficiente quanto o processo em batelada. De forma geral, pode-se concluir que a produ??o de barrilha a partir da ?gua de produ??o de petr?leo ? um processo vi?vel, transformando um efluente que causa grande impacto ambiental em mat?ria-prima de larga utiliza??o industrial
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Hurley, Jeffrey S. "Phase transfer catalysis of deuterium exchange reactions : II kinetic and mechanistic studies of the thermal decomposition of glycolate and hedta in the presence of the sodium salts of hydroxide, nitrate, nitrite, aluminate and carbonate." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/30717.
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Pohlenz, Julia [Verfasser], Max [Akademischer Betreuer] Wilke, Max [Gutachter] Wilke, Gerhard [Gutachter] Franz, and Stéphanie [Gutachter] Rossano. "Structural insights into sodium-rich silicate - carbonate glasses and melts : a combined study of trace element in-situ XAFS and Molecular Dynamics / Julia Pohlenz ; Gutachter: Max Wilke, Gerhard Franz, Stéphanie Rossano ; Betreuer: Max Wilke." Potsdam : Universität Potsdam, 2019. http://d-nb.info/1218404477/34.
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Simone, Virginie. "Développement d'accumulateurs sodium-ion." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI092/document.
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Au vu d’une demande croissante pour un stockage d’énergie à grande échelle, il est préférable de se tourner vers des matériaux peu coûteux et répandus. De ce point de vue, le sodium, qui présente des caractéristiques très proches de celles du lithium, présente également l’avantage d’être peu coûteux, abondant et réparti uniformément dans le monde. Cette thèse porte sur l’étude d’un système complet Na-ion constitué d’un carbone dur à l’électrode négative et d’un oxyde lamellaire à l’électrode positive. Un volet sur l’électrolyte a également été abordé.Concernant l’électrode négative, l’influence de la température de pyrolyse de la cellulose sur la structure des carbones durs et sur les performances électrochimiques a été étudiée. Une graphitisation localisée, une fermeture des pores et une évolution de la porosité interne avec la température de pyrolyse ont pu être observées. Les meilleures performances électrochimiques ont été obtenues pour le matériau synthétisé à 1600 °C : une capacité réversible d’environ 300 mAh.g-1 stable sur 200 cycles est atteinte à 37,2 mA.g-1 avec une efficacité coulombique initiale de 84 %. Pour mieux comprendre les mécanismes d’insertion du sodium dans ces matériaux, des études par spectroscopie d’impédance, SAXS et EDX ont été réalisées sur des carbones durs cyclés à différents potentiels.Le matériau d’électrode positive choisi est l’oxyde lamellaire Na0,6Ni0,25Mn0,75O2. L’influence de la température de calcination a permis de faire varier le nombre de défauts d’empilement de type P3 au profit d’une phase P2 plus cristalline. Après avoir optimisé l’électrolyte à base de carbonates pour garantir la reproductibilité des tests oxyde lamellaire//sodium métal, une capacité d’oxydation de 130 mAh.g-1 a pu être atteinte au premier cycle avant de chuter fortement sur les 40 cycles suivants. Cette perte de capacité a pu être en partie expliquée par des études de DRX operando. Enfin, ces travaux ont permis d’aboutir à des systèmes complets Na-ion dont les premiers résultats sont prometteursBecause of the development of renewable energy and electric vehicles, the need for a large scale energy storage has increased. This type of storage requires a large amount of raw materials. Therefore low cost and abundant resources are necessary. Consequently the use of sodium batteries is of interest because sodium’s low cost, high abundance, and worldwide availability. This PhD thesis deals with the study of a full Na-ion cell containing a hard carbon negative electrode, and a layered oxide positive electrode. A shorter part concerns the electrolyte.Concerning the negative electrode, the first objective was to understand in detail the influence of the pyrolysis temperature of a hard carbon precursor, cellulose, on the final structure of the material and its consequences on the electrochemical performance. Many techniques were used to characterize the hard carbon structure as a function of the pyrolysis temperature. Localized graphitization, pore closure, and an increase in micropore size have been observed with increasing temperature. The best electrochemical performance has been reached with the hard carbon synthesized at 1600°C: a reversible capacity of around 300 mAh.g-1 stable over 200 cycles is obtained at 37.2 mA.g-1 with an initial coulombic efficiency of 84%. To deeper understand sodium insertion mechanisms in hard carbon structures impedance spectroscopy, SAXS and EDX were carried out on hard carbon electrodes cycled at different voltages.The layered oxide Na0.6Ni0.25Mn0.75O2 was investigated as the positive electrode. It was observed that with increasing calcination temperature the number of P3-type stacking faults decreases in favor of a more crystalline P2 phase. Then, the carbonate-based electrolyte has been optimized to guarantee the reproducibility of the electrochemical tests performed in a layered oxide//sodium metal configuration. A first oxidation capacity of around 130 mAh.g-1 is reached. However this value drops quickly after 40 cycles. Operando XRD analysis did partially explain the capacity decrease. Finally, the results of these investigations were used to design an optimized full cell which demonstrated promising performance during initial testing
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Wopperer, Philipp. "Electron photoemission from sodium and carbon clusters." Phd thesis, Université Paul Sabatier - Toulouse III, 2013. http://tel.archives-ouvertes.fr/tel-00860445.
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Des distributions angulaires (PAD) et des spectres (PES) de photoélectrons émis par des agrégats sous l'action des lasers à impulsions femtosecondes linéairement polarisées ou d'une impulsion instantanée sont calculés théoriquement dans un modèle basé sur la théorie de la fonctionnelle de la densité dépendante du temps (TDDFT). Les systèmes finis étudiés sont de petits agrégats de sodium, des chaînes de carbone C_N (N = 3, 5, 7), et le célèbre buckminsterfullerène C_60. Le comportement de l'émission éléctronique est exploré en fonction de la taille, la forme, la structure électronique et ionique ainsi qu'en fonction des paramètres du laser. En outre, des procédures de détermination de la PAD d'un ensemble de molécules ou d'agrégats orientés de façon aléatoire, sont élaborées. Les résultats de la TDDFT sont de plus comparés aux modèles stationnaires et aux données expérimentales. Les méchanismes d'ionisation sont étudiés dans le régime à un photon et à multiphoton.
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Amaral, Ian Rodrigues do. "Propriedades estruturais e vibracionais de carbonatos fosfatos isoestruturados (sidorenkiktas)." Universidade Federal do CearÃ, 2017. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=18566.
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Carbonatos fosfatos isoestruturados do tipo sidorenkitas sÃo materiais com alto potencial de aplicaÃÃo em cÃtodos dos mais modernos tipos de baterias de sÃdio. Sua estrutura lamelar permite a inserÃÃo e extraÃÃo dos Ãons de sÃdio, que sÃo a principal fonte de forÃa eletromotriz da bateria. Utilizando um elemento muito mais abundante na crosta terrestre, esses dispositivos sÃo a grande promessa para substituiÃÃo da, jà bastante difundida, bateria de Ãons de lÃtio. PorÃm, o cÃtodo que contÃm as caracterÃsticas ideais para produzir o melhor desempenho, propiciando alta densidade de energia e estabilidade quÃmica, ainda està em desenvolvimento. A espectroscopia Raman continua sendo o melhor mÃtodo para caracterizar as propriedades destes compostos, pois contÃm a grande vantagem de ser altamente sensÃvel ao ambiente molecular das ligaÃÃes do oxigÃnio com os metais de transiÃÃo, o fÃsforo e o carbono. Nesta linha, realizamos um estudo de espectroscopia Raman em um conjunto de carbonatos fosfatos do tipo Na3MCO3PO4 (M = Mn, Fe, Co e Ni), obtidos por sÃntese hidrotÃrmica em microondas a 210 ÂC por 30 minutos. O sucesso na inserÃÃo de variados metais no interior de octaedros MO6, com raios iÃnicos distintos, produz uma alteraÃÃo no volume da cÃlula unitÃria do arranjo cristalino, modificando a distÃncia de equilÃbrio das ligaÃÃes atÃmicas, provocando uma alteraÃÃo substancial no nÃmero de onda dos seus modos normais de vibraÃÃo. Por isso, visto que informaÃÃes essenciais das propriedades quÃmicas e estruturais dos mais variados tipos de carbonatos fosfatos sÃo reveladas pela tÃcnica da espectroscopia Raman de forma confiÃvel, sua utilizaÃÃo se torna indispensÃvel para o desenvolvimento de mÃtodos e o planejamento de um material eficiente e comercialmente viÃvel para as inovadoras baterias de Ãons de sÃdio.
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Thomas, Philippe. "Contribution à l'étude de l'insertion électrochimique du sodium dans différentes structures carbonées." Nancy 1, 1999. http://www.theses.fr/1999NAN10275.
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Ce travail se situe dans le cadre général de l'étude de l'insertion électrochimique de métaux alcalins dans des matériaux carbonés susceptibles d'applications comme anodes de générateurs secondaires. Une attention toute particulière est portée sur l'influence de la nature de l'électrolyte et du matériau carboné sur les performances électrochimiques (capacités réversible et irréversible, évolution en cyclage). L'insertion des ions sodium dans des électrolytes à base de solvants carbonates est décrite pour le graphite UF4 et les fibres P75. L'utilisation du carbonate d'éthylène (EC) entraîne la formation d'une couche de passivation sur l'électrode carbonée, imperméable aux molécules de solvant mais permettant la diffusion des ions sodium. Ce film passivant a été caractérisé par microscopie électronique à transmission (imagerie, diffraction électronique et spectrométrie par pertes d'énergie des électrons transmis). Alors que l'emploi du carbonate de propylène (PC) conduit à l'exfoliation des domaines graphités, les électrodes peuvent être cyclées soit en utilisant des mélanges EC-PC ou ChloroEC-PC soit après formation d'un film de passivation dans EC préalablement au cyclage dans PC. L'étude de l'insertion du sodium dans des fibres de carbone issues de précurseurs différents (brai mésophase ou polyacrylonitrile (PAN)) a permis de mettre en évidence deux mécanismes de fixation de l'alcalin. L'intercalation entre les feuillets de graphène est le mécanisme majoritaire pour les fibres ex-brai alors que l'insertion dans la porosité devient significative pour les fibres ex-PAN. Des produits contenant une quantité notable de sodium et cyclant réversiblement peuvent alors être synthétisés. Enfin, une étude préliminaire concerne l'insertion du sodium dans des graphites modifiés par broyage, soit chimiquement par suroxydation électrochimique. Le graphite naturel UF4, dans lequel l'insertion du sodium ne conduit qu'à des produits très pauvres, peut ainsi, après broyage, intercaler des quantités importantes de sodium (NaC11). Les moyens d'optimiser les performances électrochimiques des matériaux anodiques sont alors discutés.
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Adhoum, Nafaâ. "Insertion du sodium et pénétration de l’électrolyte dans le carbone en milieu NaF fondu à 1025°C." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0185.
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Pendant l’électro-élaboration de l’aluminium par le procédé Hall-Héroult en milieu de cryolite fondue, il y a production parasite de sodium qui imprègne le carbone du bloc cathodique, suivi de près par l’électrolyte. Ceci provoque le gonflement du carbone et conduit à la limitation de la durée de vie de la cellule d’électrolyse. Dans l’objectif d’élucider les mécanismes d’interaction entre le sodium et le carbone, nous avons mené une étude de cinétique électrochimique en milieu NaF pur fondu à 1025°C. L’utilisation de diverses techniques électrochimiques (voltampérométrie, chronopotentiométrie et coulométrie) a mis en évidence l’existence d’une interaction complexe entre le sodium et le carbone. En effet, le métal alcalin est distribué entre deux types de sites correspondant à deux activités différentes. La forme la moins fortement liée au carbone correspond au sodium piégé dans la micro-porosité, alors que la forme plus stable est attribuée au sodium inséré entre les plans de graphène. Nous avons aussi montré l’existence d’un transfert lent et irréversible des espèces piégées vers les sites normaux d’insertion. De plus, en raison de l’évaporation du sodium à partir de l’interface, le produit Na-C subit une décomposition. Le transport du métal alcalin dans le réseau hôte est limité par une transition de phase du premier ordre. En tenant compte de toutes ces observations expérimentales, nous avons proposé un mécanisme réactionnel, construit le modèle mathématique associé et résolu le système d’équations différentielles, ainsi obtenu, en utilisant la méthode des différences finies. Les résultats obtenus montrent un bon accord entre les courbes théoriques et les résultats expérimentaux et permettent l’estimation des différents paramètres cinétiques des processus d’interaction Na-C. Enfin, nous avons montré que la pénétration du sodium provoque un changement de la tension interfaciale NaF-C et induit la progression du bain fondu par capillarité à partir d’une fraction molaire minimale en sodium (XNa=1,4. 10-2)One of the most important factors causing the failure of carbon cathode, during aluminum electrolysis by Hall-Héroult process, is the uptake of sodium which leads to a macroscopic swelling of cathode. To understand the fundamental mechanism of sodium-carbon interaction, we carried our electrochemical kinetic study in a pure molten NaF electrolyte at 1025°C. We proved the occurrence of a complex interaction between sodium and carbon. Indeed, sodium is showed to be distributed between two kinds of sites in the host material : normal sites in the Van der Wals gap between the carbon’s plans and traps which are located at microporosity and dislocations. We also showed the occurrence of a slow and irreversible transfer of sodium from traps to normal intercalation sites. Moreover, sodium transport in carbon matrix is found to be limited by a first order phase transition. Taking into account all these experimental observations, we suggested a complete mechanism scheme and developed a mathematical model which allowed the recovery, with a good accuracy of the experimental results
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Vivaldi, Daniele. "Modeling of underexpanded reactive CO2-into-sodium jets, in the frame of sodium fast reactors." Thesis, Saint-Etienne, EMSE, 2013. http://www.theses.fr/2013EMSE0707/document.
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Ce travail de thèse s’est inscrit dans le contexte d’utilisation d’un cycle de conversion de l’énergie de type Brayton au CO2 supercritique, pour les réacteurs à neutrons rapides refroidis au sodium (RNRNa). Dans le cas d’une fuite accidentelle dans l’échangeur de chaleur Na − CO2 d’un RNRNa, le CO2, avec une pression opérative d’environ 200 bars, serait injecté dans le sodium liquide qui se trouve à basse pression,provoquant un jet sous-détendu et réactif deCO2 dans le sodium. L’objectif principal de ce travail de thèse était le développement d’un modèle numérique du jet réactif diphasique de CO2 dans du sodium.Un modèle numérique d’un jet sous-détendu non-réactif de gaz dans du liquide, utilisant une approche3D non-stationnaire de type multi-fluide CFD, a été développé. Les résultats numériques ont été validés à travers la comparaison avec résultats expérimentaux obtenus avec mesures optiques. Un modèle décrivant la réaction chimique entre le sodium et le CO2 a été ensuite développé et intégré dans le modèle 3D multi-fluide. Le modèle résultant permet de calculer les profils de température obtenus au sein du jet et sur les parois des tubes de l’échangeur de chaleurThis PhD work was motivated by the investigations in the frame of supercritical CO2 Brayton cycles as possible energy conversion cycles for the Sodium-cooled Fast nuclear Reactors (SFRs). Following an accidental leakage inside the sodium-CO2 heat exchanger of a SFR, the CO2, having an operating pressure of about 200 bars, would be injected into the low-operatingpressure liquid sodium, creating an underexpanded reactive CO2-into-sodium jet. The goal of this PhD work is the development of a numerical model of the two-phase reactive CO2-into-sodium jet.A numerical model of an underexpanded non-reactive gas-into-liquid jet was developed, adopting a 3D unsteady multi-fluid CFD approach. The numerical results have been validated through the experimental results obtained with a facility employing optical probe technique. A numerical model for the chemical reaction between sodium and CO2 was then developed and integrated into the 3D two-fluid model. The resulting model allows to determine the temperature profiles inside the reactive jet and on the heat exchanger tubes
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Srisuwan, Nakarin Pébère Nadine. "Propriétés inhibitrices d'un mélange d'amines grasses et de sébaçate de sodium vis-à-vis de la corrosion d'un acier au carbone." Toulouse : INP Toulouse, 2008. http://ethesis.inp-toulouse.fr/archive/00000707.
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Saavedra, Rios Carolina del Mar. "Etude des carbones durs issus de la biomasse pour l’application dans les batteries Sodium-ion." Thesis, Université Grenoble Alpes, 2020. https://thares.univ-grenoble-alpes.fr/2020GRALI072.pdf.
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La demande croissante en batteries Lithium-ion a suscité une certaine inquiétude concernant l'approvisionnement en matières premières critiques nécessaires à leur production, en particulier les ressources en Li, Co, Ni et Cu. La technologie Sodium-ion apparait comme une alternative pouvant utiliser des ressources abondantes et uniformément réparties, et qui pourrait réduire le coût des batteries par rapport au Lithium-ion. Toutefois, le débouché commercial des batteries Sodium-ion est encore limité par le développement de matériaux d'électrode négative à haute performance et bas coût. L'option la plus prometteuse est un matériau carboné désordonné appelé carbone dur, obtenu par traitement thermique à haute température de précurseurs organiques. Malgré ses bonnes performances, le carbone dur est toujours plus cher que le graphite utilisé dans les batteries Lithium-ion, étant donné le coût élevé de ses précurseurs synthétiques. La biomasse lignocellulosique a récemment attiré l'attention en tant que précurseur du carbone dur, étant donné sa nature renouvelable, son accessibilité et son faible coût. Cependant, la grande variabilité des matières premières de la biomasse ainsi que le faible rendement de la réaction de pyrolyse, rendent leur application commerciale plutôt difficile. De plus, le rôle de la composition de la biomasse sur les propriétés du carbone dur n’est pas complètement compris. Le travail de recherche présenté ici est une approche interdisciplinaire, visant à élucider l'impact de la composition de la biomasse sur les propriétés physico-chimiques et électrochimiques des carbones durs résultants ainsi que le rendement de leur synthèse. Un ensemble de 25 précurseurs ont été sélectionnés pour cette étude. La composition de chaque précurseur, telles que le contenu organique et inorganique élémentaire, et le contenu macromoléculaire, ont été évaluées. Les carbones durs synthétisés ont été caractérisés par des techniques de XRD, Raman, SEM, TEM, SAXS, XPS et de cyclage galvanostatique. Le contenu et la composition inorganique du précurseur, en particulier la présence de composés de Si, Ca et K, ont semblé jouer un rôle essentiel dans le développement de la structure et de la surface du carbone dur. Par conséquent, ils ont un impact négatif important sur les performances du carbone dur, en produisant des irréversibilités élevées. Compte tenu de leur faible teneur en cendres couplé à leur faible cout et leur faible impact environnemental, les résidus forestiers et certain résidus agricoles, semblent être le meilleur compromis pour l'application du carbone durThe ever-increasing demand for Lithium-ion batteries has raised some concern regarding the supply of the critical raw materials needed for their production, especially the Li, Co, Ni and Cu resources. The Sodium-ion technology appears to be an alternative which potentially uses abundant, and evenly distributed resources, that is able to reduce the cost of the batteries compared to Lithium-ion. However, the commercial intrusion of Sodium-ion batteries is still limited by the development of low-cost and high-performance negative electrode material. The most promising option is a disordered carbonaceous material called hard carbon obtained from high-temperature thermal treatment of organic precursors. Despite its good performance, hard carbon is still more expensive than the graphite used in Lithium-ion batteries, given the high cost of the synthetic precursors. Lignocellulosic biomass has recently attracted attention as a hard carbon precursor, given its renewable nature, accessibility, and low cost. However, the high variability of biomass feedstock, together with the poor yield of the pyrolysis reaction, make their commercial application rather difficult. Moreover, there is no clear understanding of the biomass composition role on the hard carbon properties. The research work presented here is an interdisciplinary approach, aiming to elucidate the biomass composition's impact on the physicochemical and electrochemical properties of the derived hard carbons as well as their synthesis yield. A set of 25 lignocellulosic biomass precursors have been selected for this study. The composition of each biomass precursor, such as the elemental organic and inorganic content, and the macromolecular contents were evaluated in detail. The synthesised hard carbons were characterised by XRD, Raman, SEM, TEM, SAXS, XPS, and galvanostatic cycling techniques. The inorganic content and composition of the precursor, particularly the presence of Si, Ca, and K compounds, was observed to play a critical role in developing the hard carbon structure and surface. Therefore, they have a strong negative impact on hard carbon performances, producing high irreversibility. Because of their low ash-content, coupled with their low cost and environmental impact, precursors such as forestry residues, and some agricultural residues, appeared to be the best compromise for hard carbon application
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Liu, Weiqing. "Solutions de cellulose et matériaux hybrides/composites à base de liquides ioniques et solvants alcalins." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2013. http://pastel.archives-ouvertes.fr/pastel-00819908.
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La cellulose, composé organique le plus courant et polysaccharide le plus abondant sur Terre, est une ressource naturelle très importante. Les initiatives pour remplacer totalement ou partiellement les polymères pétrochimiques conventionnels avec des bio-polymères à base de cellulose ont donc attiré l'intérêt des chercheurs ces dernières décennies, non seulement parce que la cellulose est renouvelable et biodégradable, mais aussi en raison de ses propriétés intéressantes telles que la biocompatibilité et la stabilité chimique. De plus, les propriétés de cellulose peuvent être encore améliorées par des procédés chimiques, des modifications physiques ou en préparant des composites avec des charges fonctionnelles.Les études concernant d'étudier plusieurs aspects fondamentaux comme la dissolution de la cellulose afin de produire des matériaux et le test de nouveaux concepts autour de la modification de surface ou des revêtements, à l'échelle du laboratoire. Nous présentons dans ce manuscrit nos travaux concernant la caractérisation de solutions de cellulose dans deux solvants différents (hydroxyde de sodium aqueux et un liquide ionique) et la préparation de deux nouveaux types de matériaux à base de cellulose (un matériau hybride cellulose-amidon et un composite cellulose-noir de carbone), qui sont tous les deux préparés à partir de ces solutions de cellulose.
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Srisuwan, Nakarin. "Propriétés inhibitrices d'un mélange d'amines grasses et de sébaçate de sodium vis-à-vis de la corrosion d'un acier au carbone." Phd thesis, Toulouse, INPT, 2008. http://oatao.univ-toulouse.fr/7758/1/srisuwan.pdf.
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Ce travail porte sur l’inhibition de la corrosion d’un acier au carbone dans une solution de NaCl 200 mg.L-1 par une formulation inhibitrice non toxique utilisée pour le traitement des eaux des circuits de refroidissement. Elle est constituée d’amines grasses (AG) et de sébaçate de sodium (SS). Le tracé des courbes de polarisation et la spectroscopie d’impédance électrochimique ont été utilisées afin de caractériser le mode d’action de chaque inhibiteur et d’optimiser les concentrations de chacun des composés dans le mélange. Un maximum d’efficacité a été obtenu en présence de 50 mg.L-1 AG + 1,5 g.L-1 SS. Un mécanisme d’adsorption coopérative des deux composés explique l’effet de synergie observé. Le film inhibiteur est constitué d’un mélange d’oxyde/hydroxyde de fer incorporant les molécules organiques. La détermination des énergies de surface a confirmé la mécanisme d’adsorption coopérative proposé à partir des mesures électrochimiques.