Academic literature on the topic 'Kinetic Thermodynamic parameters'
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Journal articles on the topic "Kinetic Thermodynamic parameters"
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Zhang, Jin-Ye, and Xiao-Qing Zhu. "Comparison between 1,2-Dihydropyridine and 1,4-Dihydropyridine on Hydride-Donating Ability and Activity." Molecules 27, no. 17 (2022): 5382. http://dx.doi.org/10.3390/molecules27175382.
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In this paper, detailed comparisons of the driving force in thermodynamics and intrinsic force in the kinetics of 1,2-dihydropyridine and 1,4-dihydropyridine isomers of PNAH, HEH, and PYH in hydride transfer reactions are made. For 1,2-PNAH and 1,4-PNAH, the values of the thermodynamic driving forces, kinetic intrinsic barriers, and thermo-kinetic parameters are 60.50 and 61.90 kcal/mol, 27.92 and 26.34 kcal/mol, and 44.21 and 44.12 kcal/mol, respectively. For 1,2-HEH and 1,4-HEH, the values of the thermodynamic driving forces, kinetic intrinsic barriers, and thermo-kinetic parameters are 63.40 and 65.00 kcal/mol, 31.68 and 34.96 kcal/mol, and 47.54 and 49.98 kcal/mol, respectively. For 1,2-PYH and 1,4-PYH, the order of thermodynamic driving forces, kinetic intrinsic barriers, and thermo-kinetic parameters are 69.90 and 72.60 kcal/mol, 33.06 and 25.74 kcal/mol, and 51.48 and 49.17 kcal/mol, respectively. It is not difficult to find that thermodynamically favorable structures are not necessarily kinetically favorable. In addition, according to the analysis of thermo-kinetic parameters, 1,4-PNAH, 1,2-HEH, and 1,4-PYH have a strong hydride-donating ability in actual chemical reactions.
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Vogel, Kristina, Thorsten Greinert, Monique Reichard, Christoph Held, Hauke Harms, and Thomas Maskow. "Thermodynamics and Kinetics of Glycolytic Reactions. Part II: Influence of Cytosolic Conditions on Thermodynamic State Variables and Kinetic Parameters." International Journal of Molecular Sciences 21, no. 21 (2020): 7921. http://dx.doi.org/10.3390/ijms21217921.
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For systems biology, it is important to describe the kinetic and thermodynamic properties of enzyme-catalyzed reactions and reaction cascades quantitatively under conditions prevailing in the cytoplasm. While in part I kinetic models based on irreversible thermodynamics were tested, here in part II, the influence of the presumably most important cytosolic factors was investigated using two glycolytic reactions (i.e., the phosphoglucose isomerase reaction (PGI) with a uni-uni-mechanism and the enolase reaction with an uni-bi-mechanism) as examples. Crowding by macromolecules was simulated using polyethylene glycol (PEG) and bovine serum albumin (BSA). The reactions were monitored calorimetrically and the equilibrium concentrations were evaluated using the equation of state ePC-SAFT. The pH and the crowding agents had the greatest influence on the reaction enthalpy change. Two kinetic models based on irreversible thermodynamics (i.e., single parameter flux-force and two-parameter Noor model) were applied to investigate the influence of cytosolic conditions. The flux-force model describes the influence of cytosolic conditions on reaction kinetics best. Concentrations of magnesium ions and crowding agents had the greatest influence, while temperature and pH-value had a medium influence on the kinetic parameters. With this contribution, we show that the interplay of thermodynamic modeling and calorimetric process monitoring allows a fast and reliable quantification of the influence of cytosolic conditions on kinetic and thermodynamic parameters.
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Barghamadi, Mohammad. "Isothermal kinetics and thermodynamics studies of curing reaction of epoxy-aromatic diamine reinforced with epoxy functional MWCNT." High Performance Polymers 29, no. 7 (2016): 827–35. http://dx.doi.org/10.1177/0954008316660367.
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This study reports the cure kinetics and thermodynamics of an epoxy functional multiwall carbon nanotube-containing epoxy nanocomposite obtained by the polymerization of diglycidyl ether of bisphenol A with diaminodiphenyl sulfone as a curing agent through isothermal technique of differential scanning calorimetry. Isothermal kinetic parameters including reaction orders ( m, n), rate constants ( k1, k2), activation energy ( Ea), and pre-exponential factor ( A) were estimated using Kamal autocatalytic model. The model gives a good description of curing kinetics at various temperatures prior to the onset of vitrification. Thermodynamic parameters such as enthalpy (Δ H#), entropy (Δ S#), and Gibbs free energy (Δ G#) changes were also determined using the rate constants from the isothermal kinetic analysis and transition state theory. The thermodynamic functions were shown to be very sensitive parameters for the evaluation of the cure reaction.
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Yablonsky, Gregory S., Denis Constales, and Guy B. Marin. "Single-Route Linear Catalytic Mechanism: A New, Kinetico-Thermodynamic Form of the Complex Reaction Rate." Symmetry 12, no. 10 (2020): 1748. http://dx.doi.org/10.3390/sym12101748.
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For a complex catalytic reaction with a single-route linear mechanism, a new, kinetico-thermodynamic form of the steady-state reaction rate is obtained, and we show how its symmetries in terms of the kinetic and thermodynamic parameters allow better discerning their influence on the result. Its reciprocal is equal to the sum of n terms (n is the number of complex reaction steps), each of which is the product of a kinetic factor multiplied by a thermodynamic factor. The kinetic factor is the reciprocal apparent kinetic coefficient of the i-th step. The thermodynamic factor is a function of the apparent equilibrium constants of the i-th equilibrium subsystem, which includes the (n−1) other steps. This kinetico-thermodynamic form separates the kinetic and thermodynamic factors. The result is extended to the case of a buffer substance. It is promising for distinguishing the influence of kinetic and thermodynamic factors in the complex reaction rate. The developed theory is illustrated by examples taken from heterogeneous catalysis.
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Gandova, Vanya, and Ivalina Petrova. "Black chokeberry (Aronia melanocarpa) copigmentation reaction: Thermodynamic and kinetic investigations." BIO Web of Conferences 122 (2024): 01001. http://dx.doi.org/10.1051/bioconf/202412201001.
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Two type of parameters (thermodynamics and kinetics) were used to determine thermal stability of copigmentation process in black chokeberry: chlorogenic acid system. According to thermodynamic investigations copigmentation complex was destroyed at high temperature and restored again at low temperature. Different parameters kinetic rate constant, energy of activation and z-factor were presented and the reaction Based on them the order of the reaction was determined as first order.
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Saha, Tapan K., Subarna Karmaker, and Md F. Alam. "Kinetics, mechanism and thermodynamics involved in sorption of meso-tetrakis(4-sulfonatophenyl)porphyrin onto chitosan in aqueous medium." Journal of Porphyrins and Phthalocyanines 18, no. 03 (2014): 240–50. http://dx.doi.org/10.1142/s1088424613501174.
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Sorption of meso-tetrakis(4-sulfonatophenyl)porphyrin ( H 2 tpps ) onto chitosan has been investigated in aqueous medium. Kinetic and isotherm studies were carried out by considering the effects of various parameters, such as pH, initial concentration of H 2 tpps solution, and temperature. The kinetic data obtained from different batch experiments were analyzed using pseudo first-, second-order, intraparticle, and film diffusion kinetic models. The equilibrium sorption data was analyzed by using Tempkin, Langmuir and Freundlich models. The best results were achieved with the pseudo second-order kinetic, Langmuir and Freundlich isotherm models. The intraparticle diffusion and film diffusion are the rate limiting steps. The amount of sorbate adsorbed at equilibrium (qe) increased with increasing the initial concentration of H 2 tpps solution, showing maximum sorption capacity of 445.21 μmol.g-1. The activation energy (Ea) of sorption kinetics was found to be 19.47 kJ.mol-1. Thermodynamic parameters such as change in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were evaluated by applying the Van't Hoff equation. Thermodynamic activation parameters such as change in enthalpy of activation (ΔH‡), entropy of activation (ΔS‡), and free energy of activation (ΔG‡) were also calculated. The thermodynamics of H 2 tpps sorption onto chitosan in aqueous medium indicates its spontaneous and endothermic nature.
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Van der Ven, A., J. C. Thomas, B. Puchala, and A. R. Natarajan. "First-Principles Statistical Mechanics of Multicomponent Crystals." Annual Review of Materials Research 48, no. 1 (2018): 27–55. http://dx.doi.org/10.1146/annurev-matsci-070317-124443.
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The importance of configurational, vibrational, and electronic excitations in crystalline solids of technological interest makes a rigorous treatment of thermal excitations an essential ingredient in first-principles models of materials behavior. This contribution reviews statistical mechanics approaches that connect a crystal's electronic structure to its thermodynamic and kinetic properties. We start with a description of a thermodynamic and kinetic framework for multicomponent crystals that integrates chemistry and mechanics, as well as nonconserved order parameters that track the degree of chemical order and group/subgroup structural distortions. The framework allows for spatial heterogeneities and naturally couples thermodynamics with kinetics. We next survey statistical mechanics approaches that rely on effective Hamiltonians to treat configurational, vibrational, and electronic degrees of freedom within multicomponent crystals. These Hamiltonians, when suitably constructed, are capable of extrapolating first-principles electronic structure calculations within (kinetic) Monte Carlo simulations, thereby enabling first-principles predictions of equilibrium and nonequilibrium materials properties at finite temperature.
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Chatterjee, Arobindo, and Vinit Kumar Jain. "Isothermal, Kinetic, and Thermodynamic Studies of Graphene Oxide Adsorption on Silk." AATCC Journal of Research 8, no. 5 (2021): 18–29. http://dx.doi.org/10.14504/ajr.8.5.3.
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The properties of graphene enriched silk depend on the amount of graphene oxide (GO) adsorption on silk. GO dipping parameters include the GO solution pH, initial GO concentration, dipping time and temperature, and the type of substrate. The effects of GO dipping parameters on the sorption process are studied to achieve the maximum GO adsorption on the silk surface for the preparation of an economical graphene/silk-based textile product. In addition, equilibrium isotherms, kinetics, and thermodynamics of GO adsorption on the silk surface in a batch sorption process are examined to understand the adsorption mechanism. The Freundlich isotherm best describes the adsorption of GO onto the silk. A pseudo-second order kinetic model best describes the kinetics of GO adsorption. Thermodynamic studies reveal that GO adsorption is spontaneous and exothermic.
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Xu, Huan Yan, Xue Li, Yan Li, Ping Li, and Wei Chao Liu. "Photocatalytic Degradation of Methyl Orange by TiO2/Schorl Photocatalyst: Kinetics and Thermodynamics." Applied Mechanics and Materials 713-715 (January 2015): 2789–92. http://dx.doi.org/10.4028/www.scientific.net/amm.713-715.2789.
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An active dye, Methyl Orange (MO) was employed as the target pollutant to evaluate the photocatalytic activity of TiO2/schorl composite and the kinetics and thermodynamics of this process was emphasized in this work. Langmuir–Hinshelwood kinetic model was employed for the kinetic studies and the results revealed that the process of MO photocatalytic discoloration by TiO2/schorl composite followed one order reaction kinetic equation under different conditions. The reaction rate constant (k) increased with initial MO concentration decreasing. When the catalyst dosage or solution pH increased,kvalues increased and then decreased. The possible reasons for these phenomena were discussed. Finally, the thermodynamic parameters ΔG, ΔH, ΔSwere obtained by the classical Van't Hoff equation.
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Giménez-López, Bruno, Cristhian Ronceros, Alejandro Quispe, Rosalio Cusi, Manuel Giménez-Medina, and Carmen Cuba. "Mathematical modeling of the onion drying process: Kinetic and Thermodynamic Parameters." Revista de la Facultad de Agronomía, Universidad del Zulia 41, no. 3 (2024): e244127. http://dx.doi.org/10.47280/revfacagron(luz).v41.n3.07.
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The dehydration processes of onions are governed by a series of kinetic and thermodynamic parameters that, when controlled, facilitate the identification of a mathematical model that will improve the efficiency and quality of the drying process in terms of reducing production costs, environmental sustainability, and the development of innovative products. In this study, various mathematical models were validated to accurately describe the drying process, and from them, the kinetic and thermodynamic parameters governing the dehydration processes were determined. For the experimental development, onions grown in the Ica region of Peru were peeled, cut into pieces, and dehydrated (60, 70, and 80 ºC), and five mathematical models were applied to model the drying kinetics of the process. The Midilli model was the best fit for the experimental curves. Increasing the temperature reduced the enthalpy and increased the entropy, Gibbs free energy, and effective diffusion coefficient in both varieties of onions. Determining the drying kinetics has been essential for establishing operating conditions by understanding how temperature, relative humidity, and other parameters affect the moisture removal rate, allowing for the design of optimal equipment and predicting product behavior during the drying process. Keywords: onion dehydration, mathematical models, kinetic parameters, drying efficiency, environmental sustainability.
Dissertations / Theses on the topic "Kinetic Thermodynamic parameters"
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Kumwimba, Ghislain Mutamba. "Effect of process variables on the kinetic and thermodynamic parameters of platinum solvent extraction by cyanex 921." Thesis, Cape Peninsula University of Technology, 2012. http://hdl.handle.net/20.500.11838/870.
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Thesis(MTech( Engineering))--Cape Peninsula University of Technology, 2012<br>Platinum is a precious metal which may be processed under acidic conditions. Accordingly, the extraction of platinum from an acidic chloride media is of immense practical importance. In this study, the extraction of platinum was investigated in a Pt(IV)-HCl-Cyanex 921 matrix in order to establish the effect of temperature, extractant concentration, pH and the initial platinum concentration which had been used in the evaluated solvent extraction (SX) process. The extractant phase contained a mixture of Cyanex 921 and kerosene. In addition, the extraction mechanism of platinum, and the extracted species, are also described in the study, including the determination of the following: extraction ratio, extractant loading, distribution ratio, thermodynamic parameters, and the kinetic mechanism involved in the Pt(IV)-HCl-Cyanex 921 system used. Inductively coupled plasma emission spectroscopy (ICP-ES) was used to measure the platinum concentration in the aqueous phase with a mass balance being used to determine the concentration of platinum in the organic phase.
Using a combination of the variables under investigation, the experiments which were evaluated indicated that it is possible to extract sufficient platinum chlorocomplex under the following conditions: pH of 1, Cyanex 921 concentration of 8% (v/v), temperature of 298 K and an initial platinum concentration of 55.22 mg/L. Under these conditions the maximum organic-phase loading of 253.9 mg/L was achieved as compared to the theoretical loading of 507.24 mg/L. The equilibrium loading of ~50% of the platinum chlorocomplex in the organic phase was achieved after 2400 seconds of reactor operation. In this case, a distribution ratio of 9.4 was achieved. This value was observed to be higher as compared to the other SX conditions evaluated in this study.
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Mella, Bianca. "Resíduo sólido de depilação como adsorvente de corantes para tingimento de couro." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/172097.
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Nas etapas de processamento do couro, de limpeza da pele, de recortes e ajuste da espessura do couro, diferentes tipos de resíduos sólidos são gerados. Dentre esses resíduos, os pelos provenientes da etapa de depilação são descartados. Além disso, nas etapas finais do acabamento molhado do couro, em especial no tingimento, são adicionados corantes e outros produtos químicos com o objetivo de dar ao couro características superficiais, como cor e textura, gerando, consequentemente, efluentes de difícil tratamento devido ao potencial recalcitrante dos produtos químicos. O objetivo deste trabalho é apresentar uma alternativa ao uso do pelo proveniente da etapa de depilação, possibilitando assim uma extensão no ciclo de vida deste resíduo como um adsorvente alternativo para remoção de corantes empregados na indústria do couro. O pelo (CHW) foi caracterizado através de microscopia eletrônica de varredura (MEV), espectroscopia de raios X dispersiva de energia (EDS), espectroscopia de infravermelho (FTIR), bem como sua área superficial específica e distribuição de tamanho de poro por análises de BET/BJH. A capacidade de remoção dos corantes Azul Ácido 161 (AB-161) e Preto Ácido 210 (AB-210) em soluções aquosas foi estudada emfaixas de pH de 1,0 a 10,0 e também a dosagem ótima de adsorvente. Nas isotermas de adsorção,o modelo de Liu foi o que melhor apresentou resultados para os dois corantes estudados em todas as temperaturas analisadas (30, 40 e 50ºC) No estudo cinético, o modelo de ordem-geral apresentou o melhor ajuste dos dados, com menor tempo de contato para remoção do corante AB-161 de 600 min com o pelo (CHW) e 90 min com o carvão ativado comercial (CAC), nos valores de pH 3,0 e pH 4,0, respectivamente. Para o corante AB-210 o menor tempo de contato para atingir o equilíbrio foi de 120 min e 90 min para CHW e o CAC, nos valores ótimos de pH de 2,0 e 4,0, respectivamente. O carvão produzido (AC-CHW) a partir do pelo residual foi ativado com H3PO4, caracterizado e testado em efluentes reais para remoção dos corantes Laranja Ácido 142 (AO-142) e Marrom Ácido 414 (AB-414). O carvão produzido apresentou um elevado diâmetro de poro (140,70 A), o que favoreceu a adsorção de moléculas maiores e mais complexas, como as presentes nos efluentes reais. Através do MEV e do FTIR observou-se a presença dos compostos estudados no AC-CHW após aadsorção, onde os resultados indicaram que os grupos funcionais de -CH=CH- participaram ativamente do processo de remoção. O pHzero obtido do AC-CHWfoi de 3,65, o que favoreceu a remoção desses compostos já que o efluente real apresenta um pH inferior a 4,0. Os percentuais de remoção obtidos de área sob as curvas de adsorção indicam uma remoção de 51,94% e 49,73% dos efluentes contendo AB-414 e AO-142, respectivamente.<br>In the stages of leather processing, skin cleansing, trimming and leather thickness adjustment, different types of solid waste are generated. Among these residues, hairs from the depilation stage are discarded. In addition, in the final stages of the wet finishing of leather, in particular in dyeing, dyes and other chemical products are added with the aim of giving the leather surface characteristics, such as color and texture, thus generating effluents that are difficult to treat due to the potential recalcitrant of chemicals. The objective of this work is to present an alternative to the use of hair from the depilation stage, thus allowing an extension in the life cycle of this residue as an alternative adsorbent for the removal of dyes used in the leather industry. The hair (CHW) was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), infrared spectroscopy (FTIR), as well as its specific surface area and pore size distribution by analysis of BET/BJH. The ability to remove Acid Blue 161 (AB-161) and Acid Black 210 (AB-210) dyes in aqueous solutions was studied in pH ranges from 1 to 10 and also the optimum dosage of adsorbent. In the adsorption isotherms, Liu model presented the best results for the two dyes studied at all temperatures (30, 40 and 50ºC). In the kinetic study, the general-order model presented the best fit of the data, with a lowest contact time to remove the AB-161 dye of 600 min with the hair (CHW) and 90 min with the commercial activated charcoal (CAC) at pH 3.0 and pH 4.0, respectively For the dye AB-210, the lowest contact time to reach equilibrium was 120 min and 90 min for CHW and CAC, at the optimum pH values of 2.0 and 4.0, respectively. The charcoal produced (AC-CHW) from the residual was activated with H3PO4, characterized and tested in actual effluents to remove the Acid Orange 142 (AO-142) and Acid Brown 414 (AB-414) dyes. The carbon produced had a high pore diameter (140,70 A), which favored the adsorption of larger and more complex molecules, such as those present in the actual effluents. The presence of the compounds studied in the AC-CHW after adsorption was observed through the SEM and the FTIR, where the results indicated that the functional groups of -CH = CH- actively participated in the removal process. The obtained pHzero of AC-CHW was 3.65, which favored the removal of these compounds since the actual effluent had a pH lower than 4.0. The percentages of removal obtained from area under the adsorption curves indicate a 51.94% and 49.73% removal of the effluents containing AB-414 and AO-142, respectively.
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Mougel, Marylène. "Mecanisme de reconnaissance arn-proteine dans le risobome d'escherichia coli : etude des sites de fixation des proteines s8 et s15 sur l'arn 16s." Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13198.
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Zuo, Fei. "Etude thermodynamique et cinétique du frittage par micro-ondes de l’alumine : influence des paramètres de la poudre." Thesis, Saint-Etienne, EMSE, 2014. http://www.theses.fr/2014EMSE0752/document.
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Le frittage par micro-ondes est une nouvelle technologie de chauffage rapide utilisée pour l’élaboration de matériaux par le procédé de métallurgie des poudres. Cette méthode de frittage est non seulement économique en temps et en énergie, mais peut aussi permettre d’améliorer les propriétés finales du matériau. Cependant, l’effet bénéfique que peut apporter le chauffage par rayonnement micro-ondes n'est pas encore complètement compris.Dans ce cadre, cette thèse porte sur la mise en œuvre et les comparaisons des comportements en frittages conventionnel et micro-ondes multimodes (2,45 GHz) de l’alumine. La densification et l'évolution de la microstructure des échantillons frittés ont été analysés et comparés entre ces deux processus de chauffage en relation avec la nature des poudres de l'alumine : surface spécifique et teneur en dopant magnésie.A partir du suivi dilatométrique du frittage au cours des traitements conventionnel et micro-ondes, nous déterminons en anisotherme les énergies d’activation apparentes, qui sont considérées comme les paramètres importants de la thermodynamique de frittage : les valeurs trouvées sont toujours plus faibles dans le cas du frittage sous champ électromagnétique, preuve que les diffusions conduisant à la densification sont favorisées. Le suivi in situ permet aussi de déterminer les mécanismes de frittage (étude cinétique), par exploitation des courbes obtenues en traitement isotherme : la diffusion aux joints de grains reste le mécanisme dominant dans la plupart des cas, sauf pour une nanopoudre où la réaction d’interface devient le mécanisme limitant sous champ micro-ondes, preuve là encore de l’influence du champ électromagnétique sur la diffusion.Nous avons ainsi mis en évidence et expliqué les effets d’un champ électromagnétique sur le phénomène de densification, contribuant à terme à la maîtrise de l’application du rayonnement micro-ondes dans l’industrie céramique<br>Microwave energy has been successfully applied as a heating source in the field of powder metallurgy. Compared with conventional heating techniques, microwave sintering has a high potential to reduce the processing time as well as temperature, and to optimize functional properties. However, the detailed explanation of this enhanced effect underlying microwave sintering is still under debate.Taking into account those issues, the objective of this work was to investigate comparatively conventional and 2.45 GHz microwave multimode sintering of alumina. The densification behavior and microstructure evolution of alumina powders with different MgO doping levels as well as specific surface areas have been systematically and quantitatively studied.By the way of dilatometric measurements in both conventional and microwave processes, studies in terms of thermodynamics were carried out in non-isothermal conditions. The apparent activation energy values are significantly lowered when microwave is applied, indicating a microwave-induced enhancement on diffusion. Furthermore, densification kinetics was isothermally taken in order to study in more detailed manner the mechanism(s) involved during microwave sintering. It suggests that the grain boundary diffusion is the dominant mechanism in most cases, except for a nanopowder. In the case of fine-grained alumina, it was assumed that microwave-assisted densification is controlled by in-series “interface-reaction / grain-boundary diffusion” mechanism. But anyway, grain-boundary diffusion has been always enhanced by microwave non-thermal effect.This work will be meaningful to develop the in-depth understanding of the microwave sintering process at both the fundamental and the applied levels
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Galey, Basile. "Développement de poudres à base de MgH2 et de complexes de métaux de transition pour le stockage solide de l’hydrogène." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1264.
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Le développement de l’hydrogène en tant que nouveau vecteur d’énergie demande de pouvoir le stocker à grande échelle, dans des conditions d’encombrement, de coût énergétique et de sécurité acceptables. Le stockage sous forme solide dans des hydrures métalliques réversibles, constitue une solution particulièrement sûre et intéressante pour des applications dans le secteur des transports. Parmi de nombreux matériaux possibles, le système Mg/MgH2, constitue l’un des meilleurs candidats : abondant, bon marché, capacité de stockage réversible et élevée (7,6 % H2 en masse). Son utilisation à l’échelle industrielle est néanmoins limitée par les cinétiques de sorption très lentes et la stabilité thermodynamique importante (enthalpie de formation élevée) nécessitant des températures de fonctionnement supérieure à 300 °C. Ce projet vise au développement de composites à base de MgH2 et d’additifs avec des propriétés de stockage améliorées. L’originalité des travaux menés repose sur le type d’additifs choisi, les complexes de métaux de transition (centre métallique : Ni et Ru, ligands organiques : phosphines). En effet, ces derniers ne sont pour le moment que très peu utilisés dans la littérature. L’objectif de ce travail de thèse est donc d’explorer leur potentiel et leur efficacité pour améliorer les propriétés de stockage du système Mg/MgH2. Différents composites "MgH2 + complexe" ont été préparés par broyage et imprégnation et les cinétiques de sorption des systèmes obtenus ainsi que leurs paramètres thermodynamiques ont été déterminés par analyse thermique (DTP, DSC, PCT). Enfin, de nombreuses techniques de caractérisation physico-chimiques (DRX, RMN, XPS, MEB, MET) ont été utilisées afin de comprendre les phénomènes se déroulant lors de l’hydrogénation et la déshydrogénation des composites préparés. Le meilleur système « MgH2 + complexe » préparé durant ce travail (MgH2 dopé avec 20 % du complexe NiHCl(PCy3)2) est capable d’absorber 6 % en masse d’H2 à 100 °C en 30 min et de libérer son hydrogène sous vide à 200 °C. Les énergies d’activation apparentes et enthalpies de formation de ce composite sont respectivement de 22 et –65 kJ/mol H2 pour l’hydrogénation (contre 200 et –74,7 kJ/mol H2 pour du Mg commercial) et de 127 et 63 kJ/mol H2 pour la déshydrogénation (contre 239 et 74,7 kJ/mol H2 pour du MgH2 commercial)<br>Although hydrogen is widely recognized as a promising energy carrier, its widespread adoption as alternative to fossil fuels depends critically on the ability to store hydrogen at adequate densities, cost and security. Application devices are far from a valuable technology, and fundamental research is still required. In this regard, solid-state systems present the advantage of denser and safer hydrogen storage. Among them, Mg/MgH2 is considered as a highly promising material in terms of reversibility, cost, gravimetric and volumetric capacity. However, high thermodynamic stability (high formation enthalpy) and slow hydrogen sorption kinetics limits its practical applications.This project aims to develop Mg/MgH2-based systems with improved hydrogen storage properties thanks to the use of additives. The originality of this work is brought by the kind of additive chosen, transition metal complexes (Ni and Ru based, with phosphine ligands). Indeed, they are, for now, only very little used in the literature. The objective of this work is therefore to study their potential and their efficiency to improve the hydrogen storage properties of the Mg/MgH2 system. Different “MgH2 + complex” composites were prepared by ball milling and impregnation method and the sorption kinetics and thermodynamic parameters of the formed systems were studied by TPD, DSC and PCT analyses. Finally, XRD, NMR, XPS, SEM and TEM techniques were used to understand the phenomena taking place during the hydrogenation and the dehydrogenation of the prepared composites.The best “MgH2 + complex” system prepared during this work (MgH2 doped with 20 wt% of NiHCl(PCy3)2 complex) is able to absorb 6 wt% of H2 at 100 °C in 30 min, and to release the stored hydrogen at 200 °C under vacuum. The apparent activation energies and the formation enthalpies of the composite are respectively of 22 and –65 kJ/mol H2 for the hydrogenation reaction (against 200 and –74,7 kJ/mol H2 for commercial Mg) and of 127 and 63 kJ/mol H2 for dehydrogenation (against 239 and 74,7 kJ/mol H2 for commercial MgH2)
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Marcaud, Hélène. "Etude sur les transitions coopératives et les cinétiques de transconformation associées dans les acides nucléiques." Paris 6, 1986. http://www.theses.fr/1986PA066514.
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Tioual-Demange, Sarah. "Modélisation d’évolutions microstructurales dans les alliages de titane." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0293.
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L’étude réalisée porte sur le calcul des cinétiques de transformation de phase β → α + β et la prédiction des microstructures résultantes au cours des traitements thermiques isothermes appliqués à trois alliages de titane industriels Ti17, Ti6242 et Ti6246 et un alliage ternaire TiMoO, en poursuivant l’enrichissement du modèle TITAN, développé Di Napoli (2010). Nous avons étudié la sensibilité du modèle à plusieurs paramètres d’entrée, en distinguant deux domaines de températures : le domaine des morphologies aux joints de grains αgb + αwgb et le domaine de la morphologie intragranulaire αwi. Parmi ces paramètres : l’épaisseur critique d’apparition de la morphologie αwgb et l’espacement entre les lamelles, afin de déterminer un jeu de données pour les différents alliages et températures étudiées ; les énergies de joints de grains σββ, qui présentent une influence importante sur la germination et la croissance des trois morphologies de phase α ; le rapport d’aspect des sphéroïdes αwi, qui varie en fonction de la température de maintien isotherme ; les paramètres thermodynamiques et les diffusivités des éléments d’alliage, qui contrôlent la recherche de l’équilibre thermodynamique, et dont l’étude a permis de mettre en exergue des évolutions très complexes. L’influence de la température de maintien isotherme et de la composition de l’alliage sur les cinétiques de transformation de phase a également été traitée. Ces études ont permis d’établir un TTT calculé de l’alliage Ti17, en accord avec les résultats expérimentaux<br>The present study is mainly about the calculation of β → α + β transformation kinetics and the prediction of resulting microstructures in three industrial titanium alloys Ti17, Ti6242 and Ti6246 and a ternary alloy TiMoO during isothermal heat treatments, by pursuing the development of TITAN model, developed by Di Napoli (2010). A study of the sensitivity of the model to several input parameters is first presented, distinguishing two temperature domains: the domain of morphologies at the grain boundaries αgb + αwgb , and the domain of the intragranular morphology αwi. Among these parameters: the critical thickness of appearance of awgb morphology and the spacing between the lamellae, in order to determine a dataset for the different alloys and temperatures studied; the σββ grain boundary energies, which have a significant influence on the nucleation and growth of the three α phase morphologies; the aspect ratio of the αwi spheroids, which varies according to the isothermal holding temperature; the thermodynamic parameters and diffusivities of the alloying elements, which control the thermodynamic equilibrium, and whose study allowed to highlight complex evolutions. The influence of the isothermal holding temperature and the alloy composition on phase transformation kinetics has also been addressed. These studies allowed to establish a calculated TTT of Ti17 alloy, in agreement with the experimental results
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Xu, Weijie. "Drug release and its relationship with kinetic and thermodynamic parameters of drug sorption onto polylactide, starch acetate, wheat gluten and soy protein fibers." 2009. http://proquest.umi.com/pqdweb?did=1709934761&sid=6&Fmt=2&clientId=14215&RQT=309&VName=PQD.
Full textAbstract:
Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009.<br>Title from title screen (site viewed September 08, 2009). PDF text: ca. 195 p. UMI publication number: AAT 3352483. Includes bibliographical references. Also available in microfilm and microfiche formats.
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Arca, Simone, Profio Pietro Di, Raimondo Germani, and Gianfranco Savelli. "MEASUREMENTS OF RELEVANT PARAMETERS IN THE FORMATION OF CLATHRATE HYDRATES BY A NOVEL EXPERIMENTAL APPARATUS." 2008. http://hdl.handle.net/2429/2300.
Full textAbstract:
Studying clathrate hydrates is, ideally, a simple task: one just have to keep water under a gas pressure. However, when trying to collect measurements in an accurate and repeatable way, things mess up. When, in particular, kinetic characterizations are required, not only pressure and temperature have to be measured: also particular parameters such as gas evolved/trapped during time, heat released/adsorbed during time, critical phenomena related to additive addition, etc, should be collected in a finer way.
In the last years a growing interest has been devoted to investigations on the effects of a wide range of compounds capable to affect the thermodynamics and, in particular, kinetics of clathrate hydrate formation. The study of the effects of these compounds, called conditioners, requires an improvement of the performances of usual lab facilities by introducing a new strategy for the measurement of further characterizing parameters. Presently no standardization of the apparatus designed for clathrate hydrate studies exists, nor any commercial instrumentations are available. Generally, apparatus used are custom-made by the same research team according with the peculiar research requirements
To do this we have designed, built, calibrated and tested a novel apparatus that, in addition to the ability of measuring usually unexplored parameters, is based on the idea of obtaining as many parameters as possible in a single formation batch. This in order to solve the problem of collecting a dataset that can be processed homogeneously, thus minimizing errors due stochastic behaviours.
Using such an apparatus, several kinds of measurement are presented here, which are related directly to the clathrate hydrate investigation fields, but also more generally related to the study of equilibrium phases involving gaseous components.
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(10732359), Aaron Afriat. "COMBUSTION CHARACTERISTICS OF ADDITIVELY MANUFACTURED GUN PROPELLANTS." Thesis, 2021.
Find full textAbstract:
<p>Additive manufacturing of gun
propellants is an emerging and promising field which addresses the limitations
of conventional manufacturing techniques. Gun propellants are manufactured
using wetted extrusion, which uses volatile solvents and dies of limited and
constant geometries. On the other hand, additive techniques are faced with the challenges
of maintaining the gun propellant’s energetic content as well as its structural
integrity during high pressure combustion. The work presented in this thesis demonstrates
the feasibility of producing functioning gun propellant grains using vibration-assisted
3D printing, a novel method which has been shown to extrude extremely viscous materials
such as clays and propellant pastes. At first, the technique is compared to
screw-driven additive methods which have been used in printing gun propellant
pastes with slightly lower energetic content. In chapter two, diethylene glycol dinitrate (DEGDN), a
highly energetic plasticizer, was investigated due to its potential to replace
nitroglycerin in double base propellants with high nitroglycerin content. A
novel isoconversional method was applied to analyze its decomposition kinetics.
The ignition and lifetime values of diethylene
glycol dinitrate were obtained using the new isoconversional method, in
order to assess the safety of using the plasticizer
in a modified double base propellant. In chapter three, a modified double base
propellant (M8D) containing DEGDN was additively manufactured using VAP. The
printed strands had little to no porosity, and their density was nearly equal
to the theoretical maximum density of the mixture. The strands were burned at
high pressures in a Crawford bomb and the burning was visualized using high
speed cameras. The burning rate equation as a function of the M8D propellant as
a function of pressure was obtained. Overall, this work shows that VAP is
capable of printing highly energetic gun propellants with low solvent content,
low porosity, with high printing speeds, and which have consistent burning
characteristics at high pressures. </p>
Books on the topic "Kinetic Thermodynamic parameters"
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Садовников, Василий. Теория гетерогенного катализа. Теория хемосорбции. Publishing House Triumph, 2021. http://dx.doi.org/10.32986/978-5-40-10-01-2001.
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This monograph is a continuation of the monograph by V.V. Sadovnikov. Lateral interaction. Moscow 2006. Publishing house "Anta-Eco", 2006. ISBN 5-9730-0017-6. In this work, the foundations of the theory of heterogeneous catalysis and the theory of chemisorption are more easily formulated. The book consists of two parts, closely related to each other. These are the theoretical foundations of heterogeneous catalysis and chemisorption. In the theory of heterogeneous catalysis, an experiment is described in detail, which must be carried out in order to isolate the stages of a catalytic reaction, to find the stoichiometry of each of the stages. This experiment is based on the need to obtain the exact value of the specific surface area of the catalyst, the number of centers at which the reaction proceeds, and the output curves of each of the reaction products. The procedures for obtaining this data are described in detail. Equations are proposed and solved that allow calculating the kinetic parameters of the nonequilibrium stage and the thermodynamic parameters of the equilibrium stage. The description of the quantitative theory of chemisorption is based on the description of the motion of an atom along a crystal face. The axioms on which this mathematics should be based are formulated, the mathematical apparatus of the theory is written and the most detailed instructions on how to use it are presented. The first axiom: an atom, moving along the surface, is present only in places with minima of potential energy. The second axiom: the face of an atom is divided into cells, and the position of the atom on the surface of the face is set by one parameter: the cell number. The third axiom: the atom interacts with the surrounding material bodies only at the points of minimum potential energy. The fourth axiom: the solution of the equations is a map of the arrangement of atoms on the surface. The fifth axiom: quantitative equations are based on the concept of a statistically independent particle. The formation energies of these particles and their concentration are calculated by the developed program. The program based on these axioms allows you to simulate and calculate the interaction energies of atoms on any crystal face. The monograph is intended for students, post-graduate students and researchers studying work and working in petrochemistry and oil refining.
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Pinto, José Carlos, and Martin Schmal. Chemical Reaction Engineering: Parameter Estimation, Exercises and Examples. Taylor & Francis Group, 2021.
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Pinto, José Carlos, and Martin Schmal. Chemical Reaction Engineering: Parameter Estimation, Exercises and Examples. Taylor & Francis Group, 2021.
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Pinto, José Carlos, and Martin Schmal. Chemical Reaction Engineering: Parameter Estimation, Exercises and Examples. Taylor & Francis Group, 2021.
Find full textBook chapters on the topic "Kinetic Thermodynamic parameters"
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Murugesh, Solairajan, T. A. M. Msagati, Venkataraman Sivasankar, and R. Hariharan. "Adsorption Investigations: Kinetic and Isotherm Models, Determination of Thermodynamic Parameters." In Surface Modified Carbons as Scavengers for Fluoride from Water. Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-40686-2_7.
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Côme, Guy-Marie. "Tables of Thermodynamic and Kinetic Data and of Molecular Parameters." In Gas-Phase Thermal Reactions. Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-015-9805-7_15.
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Bondarenko, Yu O., N. F. Voronina, and O. A. Shmatko. "Kinetic and Thermodynamic Precipitation Parameters of the Pb-Sn Solid Solutions." In Defect and Diffusion Forum. Trans Tech Publications Ltd., 2008. http://dx.doi.org/10.4028/3-908451-55-8.193.
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Bianconi, M. Lucia. "Titration Calorimetry as a Tool to Determine Thermodynamic and Kinetic Parameters of Enzymes." In Biocalorimetry 2. John Wiley & Sons, Ltd, 2005. http://dx.doi.org/10.1002/0470011122.ch9.
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Goss, Dixie J., Thomas C. Becker, and Donna J. Rounds. "Kinetic and Thermodynamic Parameters of Artemia Ribosome Subunit Interactions: The Effects of Polyamines." In Cell and Molecular Biology of Artemia Development. Springer US, 1989. http://dx.doi.org/10.1007/978-1-4757-0004-6_24.
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Lorandi, Francesca, Marco Fantin, Francesco De Bon, Abdirisak A. Isse, and Armando Gennaro. "Electrochemical Procedures To Determine Thermodynamic and Kinetic Parameters of Atom Transfer Radical Polymerization." In ACS Symposium Series. American Chemical Society, 2018. http://dx.doi.org/10.1021/bk-2018-1284.ch007.
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Kuo, Jeff (Jih Fen). "Water Quality Parameters." In Chemistry, Thermodynamics, and Reaction Kinetics for Environmental Engineers. CRC Press, 2024. http://dx.doi.org/10.1201/9781003502661-12.
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Pandey, Satya Prakash, Achyut K. Panda, and Sachin Kumar. "Thermo-kinetic Study of Arthrospira Platensis Microalgae Pyrolysis: Evaluation of Kinetic and Thermodynamics Parameters." In Clean Energy Production Technologies. Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-6810-5_8.
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"Measuring Thermodynamic and Kinetic Parameters from Localized Corrosion Processes." In Heterogeneous Electrode Processes and Localized Corrosion. John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118466360.ch4.
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Kourim, Aicha, Moulay Abderrahmane Malouki, and Aicha Ziouche. "Thermodynamic and Kinetic Behaviors of Copper (II) and Methyl Orange (MO) Adsorption on Unmodified and Modified Kaolinite Clay." In Clay and Clay Minerals [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98625.
Full textAbstract:
In this study, the adsorption of Copper Cu (II) and methyl Orange (MO) from aqueous solution, on Tamanrasset’s unmodified and modified Kaolinite clay which as low cost adsorbents, was studied using batch experiments. The adsorption study includes both equilibrium adsorption isotherms, kinetics and thermodynamics study. For the characterization of the adsorbent several properties are determined such as pH, the Specific Surface Area, the Point of Zero Charge and the Cation Exchange Capacity. Indeed, various parameters were investigated such as contact time, initial metal and dye concentration, mass of solid, pH of the solution and temperature. The adsorption process as batch study was investigated under the previews experimental parameters.
Conference papers on the topic "Kinetic Thermodynamic parameters"
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Wu, Kaisheng, Paul Mason, Gustaf Sterner, and Qing Chen. "Modeling Precipitation Kinetics during Heat Treatment with CALPHAD-Based Tools." In HT 2013, edited by B. Lynn Ferguson. ASM International, 2013. https://doi.org/10.31399/asm.cp.ht2013p0206.
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Abstract Traditionally, chemists and metallurgists have used phase diagrams and tables of thermodynamic data for understanding and making predictions related to alloy development and process improvement, such as heat treatment. However, for complex, multi-component systems that extend beyond ternaries, such an approach can be limiting. Computational thermodynamics and specifically the CALPHAD approach allows for the prediction of the thermodynamic properties and phase equilibria of multi-component, multi-phase systems based on mathematical models that describe the Gibbs energy as a function of temperature, pressure and composition for each individual phase in a system. Parameters in the numerical models capture the composition and temperature dependence in binary and ternary systems and are optimized in order to best correspond to the experimental data available and are stored in databases which are then used in conjunction with computer codes whereby extrapolations can be made into the multi-component systems of interest. Additionally, the CALPHAD method can also be extended to model atomic mobilities and diffusivities in a similar way. Thermodynamic and kinetic databases are developed through a hybrid of experiments, first-principles calculations and CALPHAD modelling. By combining the thermodynamic and mobility databases, kinetic reactions during solidification and subsequent heat treatment processes can then be simulated. Through the use of such simulations it is possible to optimize alloy compositions and predict optimal solidification processes and solution heat treatment temperature ranges without performing many time-consuming and costly experiments.
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Desai, P. S., and S. M. Kapopara. "Inhibitory Action of Xylenol Orange on Aluminum Corrosion in Hydrochloric Acid Solution." In CORROSION 2012. NACE International, 2012. https://doi.org/10.5006/c2012-01101.
Full textAbstract:
Abstract The purpose of this paper is to study the inhibition effect of xylenol orange on the corrosion of aluminum (2S Grade) in 0.4 -0.6 M HCl over the temperature range of 40-60°C. It also attempts to correlate both thermodynamic parameters and kinetic parameters with the inhibition effect. The inhibition efficiencies of xylenol orange are investigated by weight loss and potentiodynamic polarization methods. The corrosion rate of aluminum decreases with increasing inhibitor concentrations and the efficiency of inhibition increases with increasing concentration of inhibitor up to almost 87% in 0.4M HCl and up to 84% in 0.6M HCl. The concentrations of inhibitor were in the range of 2 mM to 8mM. Xylenol orange acts as a good inhibitor and inhibition efficiency increases with the inhibitor concentration, while it decreases with HCl concentration and temperature. The adsorption of inhibitor on the aluminum surface obeys the Langmuir adsorption isotherm equation. The inhibition effect is satisfactorily explained by both thermodynamic and kinetic parameters. The experimental data have been treated with adsorption theory and kinetic equations successfully. Polarization curves show that xylenol orange is a mixed-type inhibitor in hydrochloric acid.
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Vijayalakshmi, P. R., and R. Rajalakshmi. "Inhibition of Mild Steel Corrosion Using Aqueous Extract of COcos Nucifera L. Peduncle in Acidic Solutions and Their Adsorption Characteristics." In CORROSION 2013. NACE International, 2013. https://doi.org/10.5006/c2013-02303.
Full textAbstract:
Abstract Cocos nucifera L. peduncle (CNP) extract, obtained from destructive distillation, as a possible source of green inhibitor, for the corrosion of mild steel in 1 M HCl was evaluated using mass loss method, potentiodynamic polarization technique, and electrochemical impedance spectroscopy (EIS). The inhibition efficiency was found to change with variation in concentration of the inhibitor, time of immersion, and temperature. The adsorption of the inhibitor molecule onto the metal surface was found to obey El-Awady kinetic thermodynamic and Frumkin adsorption isotherm. The activation energy (Ea) and other thermodynamic parameters indicate a strong interaction between the inhibitor and the mild steel surface. Polarization measurements indicate that CNP act as a mixed type inhibitor. SEM confirmed the adsorption of inhibitor molecules on mild steel surface. Quantum chemical calculations were performed by Gaussian 03 code of programs using B3LYP /6-31 G (d) basis set, to gain some insight, about structural and electronic effects on the inhibition efficiency of the tested inhibitor. FT-IR spectral studies further corroborated the mechanism of inhibition.
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Guraieb, Paula, Elizabeth Contreras, Jin Huang, Mason Tomson, Chao Yan, and Ross Tomson. "Validation of the Activity Coefficients for Carbonates at Various High Pressure High Temperature (HPHT) and Total Dissolved Solids (TDS)." In CORROSION 2014. NACE International, 2014. https://doi.org/10.5006/c2014-4360.
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Abstract The equilibrium constants and activity coefficients are reasonably well known for most common systems from room temperature to 100°C (212°F) and 6,000 psia. However, the limited knowledge of the thermodynamic and kinetic properties of mineral systems under high pressure (24,000 psia), high temperature, 250°C (482 °F) and high TDS (360,000 mg/L) has presented a huge challenge in ultra deepwater oil and gas production. The lack of data and models for scale at these extreme temperatures and pressures increase the economic and safety and risks of offshore production. With the use of a novel apparatus, high temperature and pressure solubility experiments were performed to deduce the species activity coefficients needed for the Pitzer model. Preliminary work was done at low temperature and pressure to determine if there is reason to question the reported thermodynamic equilibrium constant values for the carbonate system then extended to high temperature and pressure to determine those parameters. The activity coefficients and the equilibrium constants of these systems at extreme temperature and pressure (xHTHP) will allow for better prediction and prevention of scale formation in deepwater wells.
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Melaragno, Giacomo, Boian Alexandrov, John Shingledecker, John Siefert, Michael Gagliano, and Jorge Penso. "Weldability Evaluation of Computationally Designed Filler Wires for Wire-Arc Additive Manufacturing of Functionally Graded Materials in Harsh Service Environments." In AM-EPRI 2024. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.am-epri-2024p0723.
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Abstract Olefin furnaces contain gravity cast U-bend fittings from Fe-Ni-Cr alloys that can experience premature failures due to a combination of harsh service conditions. The fittings undergo steep temperature variations during startup and shutdown, outer diameter (OD) oxidation from furnace flue gases, and inner diameter (ID) carburization from process fluids. As a result, cracking often occurs along large solidification grain boundaries from interconnected networks of carbides and secondary phases. To address these degradation concerns, Wire Arc Additive Manufacturing (WAAM) is being used to produce a functionally graded fitting that provides increased oxidation, carburization, creep, and thermal fatigue resistance. Three welding wire compositions have been designed based on thermodynamic and kinetic modeling techniques to address the appropriate corrosion resistance and mechanical properties needed in the OD, Core, and ID regions of the U- bend fitting cross-section. A Fe-35Cr-45Ni-0.7Nb solid welding wire is being used for the Core section, and metal-cored welding wires based around this composition with additions of Si or Al are being used for the OD and ID sections, respectively. This study involved weldability evaluation focused on understanding the microstructures and potential additive manufacturing printability challenges associated with graded WAAM structures using these welding wires. To achieve this, Cast Pin Tear Testing (CPTT) was performed to evaluate solidification cracking susceptibility of the welding wires. Additionally, Scheil calculations were performed in Thermo-Calc software to predict solidification microstructures. To validate the results, SEM characterization was conducted on cast buttons of each welding wire to identify phases in the respective microstructures. These unique data will help inform WAAM design parameters needed to produce a Functionally Graded Material (FGM) that improves the lifetime of Fe-Ni-Cr U-bend fittings in olefin furnaces.?
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Papavinasam, Sankara, R. Winston Revie, and Alex Doiron. "Predicting Internal Pitting Corrosion of Oil and Gas Pipelines: Review of Corrosion Science Models." In CORROSION 2005. NACE International, 2005. https://doi.org/10.5006/c2005-05643.
Full textAbstract:
Abstract One significant factor in the degradation of pipelines used for oil and gas production is internal pitting corrosion. A corrosion scientist typically assumes parameters influencing pitting corrosion, conducts laboratory experiments to understand the extent and influence of these parameters on corrosion rates, develops theoretical explanations (based on corrosion kinetics and/or thermodynamics), and finally integrates the influence of these parameters to develop a prediction model. This paper reviews the merits and demerits of corrosion science prediction models.
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Anderko, Andrzej, and Narasi Sridhar. "Corrosion Simulation for the Process Industry." In CORROSION 2001. NACE International, 2001. https://doi.org/10.5006/c2001-01348.
Full textAbstract:
Abstract The paper describes several approaches to perform computer simulation of corrosion occurring in the chemical process industries. While the present state of the art does not permit simulating all modes of corrosion observed in process systems, useful insights can be gained at the design stage by the inclusion of corrosion simulation tools. A thermodynamic speciation model coupled to electrochemical kinetic model is used to calculate the uniform corrosion rates in a variety of mixed acid systems. Such a model can also compute the corrosion potential; an important parameter that can determine the occurrence of a variety of localized corrosion processes. For systems undergoing localized corrosion, a semi-empirical model, involving repassivation and corrosion potentials is described. Other approaches to corrosion prediction are described briefly. Areas for further development are identified.
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Yang, Mei, Xiaolan Wang, and Richard D. Sisson. "Modeling the Gas Nitriding Process for Steels." In HT 2013, edited by B. Lynn Ferguson. ASM International, 2013. https://doi.org/10.31399/asm.cp.ht2013p0166.
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Abstract This paper describes the development of a simulation program to model gas nitriding processes for steels and replace traditional trial-and-error methods that are expensive, time-consuming, and often inaccurate. The authors introduce a compound layer growth model that simulates key nitriding outcomes, including phase composition, compound layer thickness, and nitrogen concentration profiles based on process parameters (temperature, time, and nitriding potential or dissociation rate). The model employs computational thermodynamics to construct alloy-specific Lehrer diagrams that describe phase stabilities, uses parabolic law to simulate compound layer growth kinetics, and applies constant effective nitrogen diffusivity in the diffusion zone for specific alloys at given temperatures. Validation testing on AISI 4140 steel under various nitriding conditions demonstrated excellent agreement between simulated and experimental results for both as-washed and pre-oxidized specimens, confirming that the software provides an effective tool for determining optimal nitriding parameters to meet specifications and ensure reliable performance through accurate process control.
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Raheem, Kabir, Olujide Sanni, Thibaut Charpentier, and Anne Neville. "Surface Precipitation and Growth Kinetics of Calcium Carbonate (CaCO3) Scale Using a Novel Capillary Flow Rig." In CORROSION 2021. AMPP, 2021. https://doi.org/10.5006/c2021-16560.
Full textAbstract:
Abstract The oil and gas industry is plagued with various flow assurance challenges including the formation of inorganic scale on component surfaces. Much research into scaling and inhibition is now being directed towards surface deposition as fouling on surfaces often causes operational problems and the rates cannot be predicted by consideration of bulk precipitation processes. However, achieving a mechanistic understanding of surface kinetics requires laboratory techniques that offer the ability to control thermodynamic parameters. A novel once-through capillary flow rig design based on the conventional tube blocking methodology was used to evaluate the surface formation of CaCO3 under dynamic flowing conditions; an important attribute of this set-up is that saturation ratio (SR) remains constant in the capillary cell due to the short residence time of the flowing brine, and conditions can be such that there is no bulk (pre-precipitated) crystals in the solution when it flows through the cell. This allows the decoupling of bulk and surface scaling, enabling the reliable assessment of the kinetics of scale deposits present in the capillaries and provides an improved mechanistic understanding of mineral scaling on surfaces. CaCO3 surface scaling kinetics was investigated by evaluating the induction times and gravimetric measurements of mass gain in the capillary cell. Scale precipitation tests were carried out on as-received (plain) and functionalized stainless steel substrates at three saturation ratios and flow rates ranging from 10-30 ml/min. Analyses of the induction times and deposition of scale show the significant influence of flow velocity and surface wettability on heterogeneous crystallization processes, and that scale growth on surfaces is not necessarily due to the deposition of bulk precipitated crystals.
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Das, Gaurav, Ronald D. Springer, Jerzy Kosinski, and Andre Anderko. "Induction Time Modeling for Common Scaling Minerals in the Absence and Presence of Inhibitors Using a Novel Theoretical Framework." In CONFERENCE 2023. AMPP, 2023. https://doi.org/10.5006/c2023-18805.
Full textAbstract:
Abstract Mineral scaling in the oil and gas industry poses a significant challenge for flow assurance due to changes in process conditions, such as pressure and temperature changes, dissolved gases, or incompatibility between waters that are mixed in waterflooding process and chemical treatment operations. This study focuses on understanding the scaling threat of common mineral scales (barite, celestine, gypsum, calcite) and on the effectiveness of phosphonate inhibitors at various solution conditions including the concentrations of background electrolytes and temperature. We propose a novel modeling scheme through the incorporation of the classical nucleation theory (CNT) into the Mixed Solvent Electrolyte (MSE) model. The MSE thermodynamic framework has been widely applied for modeling solubilities of numerous systems containing the scaling minerals across varying solution conditions. The strength of the framework lies in its ability to explicitly consider prevailing hydrated and anhydrous solids in conjunction with aqueous speciation in the model formulation. Especially, the MSE model is known to provide accurate estimates of scaling index/ tendency, which is a key parameter for identifying the supersaturation level of a specific solid in the solution and is a key input to the CNT. While MSE assesses scaling risk based on the scaling index, CNT provides kinetic information, i.e., an estimate of induction time, based on the continuum thermodynamic treatment of clusters. In this work, the solution chemistry of the scaling solids and the inhibitors has been first developed using the MSE model, primarily by utilizing experimental solubility data for solids and speciation data for inhibitors (as determined mainly from relevant titration curves). Subsequently, the CNT model has been parameterized using the induction time data that are available primarily from turbidimetric measurements. While the application of the CNT for scale-forming minerals in the absence of inhibitors is well established for assessing the induction time, the development of a theoretical formulation in the presence of inhibitors is still evolving. In this work, we propose a simple approximation approach to incorporate the effect of the inhibitors in the formulation of the CNT through the adjustment of the surface tension parameter. This effectively quantifies the effectiveness of multiple inhibitors on one or more scaling solids.