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Literatura académica sobre el tema "Isosteric method"

Autor: Grafiati

Publicado: 25 de mayo de 2024

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Artículos de revistas sobre el tema "Isosteric method"

Zheng, Qing Rong, Shuai Gao y Chen Jie. "Determination of the Isosteric Heat of Adsorption of Hydrogen on the Multi-Walled Carbon Nanotubes". Advanced Materials Research 512-515 (mayo de 2012): 1484–91. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.1484.

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The isosteric heat of adsorption was used to study the interaction between hydrogen molecules and the Multi-Walled Carbon Nanotubes (MWCNTs). Characterizations of the MWCNTs sample were carried out based on the N2 adsorption isotherm at 77 K and the images from TEM and HRTEM. Step by step method was used to volumetrically measure hydrogen adsorption isotherms at equilibrium temperature-pressures from 123-310 K and 0-12.3 MPa. Isosteric heats of adsorption at seven excess adsorption amounts and that at zero surface loading were respectively determined by the slopes of the adsorption isosteres and the plot of the temperature dependence of the Henry’s constants. Results show that the limit of the isosteric heat of adsorption at zero surface loading is about and the mean under the experimental condition is about . The values are in the same grade as those of hydrogen on the activated coconut charcoal but smaller than those of hydrogen on the graphitized carbon black P33, the activated carbon AX-21 and the Single-Walled Carbon Nanotubes (SWCNTs). Conclusions are drawn that relatively lower adsorption amounts and the isosteric heat of hydrogen adsorption on the MWCNTs could be ascribed to the small specific surface area and the large mesopores.

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Giraldo, Liliana, Paola Rodriguez-Estupiñán y Juan Carlos Moreno-Piraján. "Isosteric Heat: Comparative Study between Clausius–Clapeyron, CSK and Adsorption Calorimetry Methods". Processes 7, n.º 4 (10 de abril de 2019): 203. http://dx.doi.org/10.3390/pr7040203.

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This work presents the calorimetric study of five adsorbents with different chemical and textural characteristics: MOF-199, MCM-41, SBA-15, activated carbon prepared from corn cob (GACKP) and graphite. These solids were used to establish the differences between isosteric heats evaluated by three different methods: Clausius–Clapeyron (C-C), Chakraborty, Saha and Koyama (CSK) and Adsorption Calorimetry (A-Cal). The textural characterization results show solids that have values of specific surface area between 2271 m2·g−1 for the MOF-199 and 5.2 m2·g−1 for the graphite. According to the results obtained for the isosteric heats for each sample, the magnitude varies depending on the coverage of the adsorbate and the textural characteristics of each adsorbent. Solids with an organized structure have isosteric heat values that are coincident among the three methods. Meanwhile, heterogeneous solids such as activated carbon values evaluated by the CKS and C-C have a high dispersion method regarding the adsorption calorimetry method. The results obtained show that the adsorption calorimetry, being a direct experimental measurement method, presents less dispersed data. At low quantities, the isosteric heat of nitrogen adsorption decreased in the order MOF-199, GACKP, MCM-41, SBA-15 and Graphite. The order for the isosteric heats values was coherent with the surface characteristics of each of the solids, especially with the pore size distribution. Finally, throughout the coverage examined in this work, the isosteric heats for nitrogen adsorption determined by adsorption calorimetry (A-Cal) were larger than the evaluated by C-C and CSK indirect methods of vaporization. According to the results, it is shown that the adsorption calorimetry allows values of the isosteric heats of adsorption with an error of less than 2% to be established and also reveals the complex nature of the heterogeneity or homogeneity of the adsorbent.

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Yonova, Albena. "Experimental studies on equilibrium adsorption isosteres and determination of the thermodynamic quantities of polar media on alumina Al2O3". Acta Scientifica Naturalis 4, n.º 1 (1 de marzo de 2017): 34–45. http://dx.doi.org/10.1515/asn-2017-0006.

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Abstract The present work is a revieif of theoretical and experimental study on the adsorption performance of the adsorbent Alumina (Al2O3) used in the adsorption system. An experimental investigation on the equilibrium adsorption isosteres at low pressure (< 1 atm) of working pairs Al2O3/H2O and Al2O3/C2H6O2 is carried out. The isovolume measurement method is adopted in the test setup to directly measure the saturated vapor pressures of working pairs at vapor-liquid equilibrium (dG=0 and dμi=0). Quantity adsorbed is determined from pressure, volume and temperature using gas law. The isosteric heat of adsorption is calculated from the slope of the plot of lnP versus 1/T different amounts of adsorbate onto adsorbent as follows: 0,01 vol% Al2O3/H2O; 0,03 vol% Al2O3/H2O; 0,1 vol% Al2O3/H2O; 0,01 vol% Al2O3/C2H6O2; 0,03 vol% Al2O3/C2H6O2; 0,1 vol% Al2O3/C2H6O2. This study shows that adsorption working pair Al2O3 C2H6O2 has better adsorption performances than those of the A2O3/H2O. Surface acidity! is a most important property! far both adsorption and catalysis and therefore is examined structure of active sites of alumina surface. Thermodynamic parameters such as isosteric heat of adsorption, isosteric enthalpy and entropy of adsorption are critical design variables in estimating the performance and predicting the mechanism of an adsorption process and are also one of the basic requirements for the characterization and optimization of an adsorption process

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Štencl, Jiří. "Effect of temperature and water activity on heat transfer in parsley leaves in the range of temperatures 10–30 °C". Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 55, n.º 5 (2007): 181–86. http://dx.doi.org/10.11118/actaun200755050181.

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The equilibrium moisture contents of parsley leaves were measured by the gravimetric dynamic method with continuous recording of changes in sample weight. Consequently water activity values were determined. Henderson equation was found to be a good model both for moisture adsorption and desorption. Isosteric heat of sorption was defined and determined in the temperature range of 10–30 °C. Clausius-Clapeyron equation was used to calculate the isosteric heat of sorption since no dependence on temperature in the analysed range was observed. The isosteric heats of sorption (qnst) were indicated graphic in the form qnst versus moisture content. Values for isosteric heat of sorption ranged from 54.41 to 46.85 kJ/mol.

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Li, Dong. "Study on the Calculation method of the Coal and Gas Outburst Threshold". International Journal of Innovative Research in Advanced Engineering 10, n.º 02 (28 de febrero de 2023): 10–17. http://dx.doi.org/10.26562/ijirae.2023.v1002.01.

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The four undetermined parameters of the temperature-pressure-adsorption equation (TPAE) were obtained by regression of the series isothermal adsorption data of the measured middle-rank deformed coal and normal coal. The unit isosteric adsorption enthalpy (UIAE) was obtained. According to the negative value of the UIAE, adsorption is an exothermic process, desorption is an endothermic process. The coal and gas outburst threshold (OT) is defined as the product of the firmness coefficient and the unit isosteric desorption enthalpy (UIDE) to show the combined effect of adsorption thermodynamics and tectonic stress. The UIDE difference between the two coals was from 1.91 times expanded to OT difference of 5.74 times.

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Kloutse, A. F., R. Zacharia, D. Cossement, R. Chahine, R. Balderas-Xicohténcatl, H. Oh, B. Streppel, M. Schlichtenmayer y M. Hirscher. "Isosteric heat of hydrogen adsorption on MOFs: comparison between adsorption calorimetry, sorption isosteric method, and analytical models". Applied Physics A 121, n.º 4 (11 de septiembre de 2015): 1417–24. http://dx.doi.org/10.1007/s00339-015-9484-6.

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Cavalcante, Maisa D., Geovana R. Plácido, Daniel E. C. de Oliveira, Bheatriz S. M. de Freitas, Caroline Cagnin y Déborah de S. Oliveira. "Isotherms and isostatic heat of foam-mat dried yellow mombin pulp". Revista Brasileira de Engenharia Agrícola e Ambiental 22, n.º 6 (junio de 2018): 436–41. http://dx.doi.org/10.1590/1807-1929/agriambi.v22n6p436-441.

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ABSTRACT Yellow mombin has high nutritional value but is very perishable. Foam mat drying is a method that has been widely used to preserve liquid and semi-solid powdered foods. In this context, the aim of this study was to determine desorption isotherms and isosteric heat of yellow mombin (Spondias mombin L.) foam for different conditions of temperature and water activity. Powdered yellow mombin pulp was obtained by drying in forced-air oven regulated to 60 ° C. The indirect static method was used to determine the isotherms and isosteric heat, whereas water activity (aw) was determined using the Hygropalm-HP23AW-A analyzer. A B.O.D. incubator, set at 10, 20, 30 and 40 °C, was used to control the temperature, and the water activity for each temperature was between 0.220 and 0.832. The experimental data were fitted to mathematical models frequently used to represent the hygroscopicity of agricultural products, and the best model was the Modified Halsey. Integral isosteric heat of desorption of yellow mombin powder, within the water content range of 17.22 to 57.58 (% d.b.), ranged from 3198.56 to 2598.38 kJ kg-1. It was concluded that the equilibrium water content of yellow mombin pulp powder increased with the increment in water activity; desorption isotherms obtained for yellow mombin pulp powder showed sigmoid form and, with the reduction of water content, the isosteric heat increases.

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Liu, Xiu Ying, Wei Guo Sun, Zhi Qin Fan y Li Ying Zhang. "Adsorption of Methane on Several Zeolites by Monte Carlo Method". Advanced Materials Research 512-515 (mayo de 2012): 1353–57. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.1353.

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Grand Canonical Monte Carlo (GCMC) method is employed to simulate the adsorption of methane in several nanoporous zeolites. Adsorption isotherms over the temperature 177-398K and the pressure 0-12MPa are simulated. And their adsorption capacities of methane in these zeolites at different temperatures and pressures are also compared. The results show that: (1) the methane uptake is in the order of LTA>MOR>MFI at the same condition. The isosteric heat can support this conclusion: the value of isosteric heat in LTA is the largest, intermediate in MOR and the least in MFI. (2) The effects of the pore volume, channel size and the energetic interactions between zeolite and methane on adsorption amounts are considered. A large pore volume and a suitable channel size near to the kinetic diameter of a methane molecule are very important for improving the storage capacity of zeolites. Based on this, we conclude that LTA zeolite with a large pore volume and a suitable channel diameter exhibit a most efficient methane storage capacity than MOR and MFI zeolites.

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Tautz, Markus, César Saldías, Antonio Diego Lozano-Gorrín y David Díaz Díaz. "Use of a bis-1,2,3-triazole gelator for the preparation of supramolecular metallogels and stabilization of gold nanoparticles". New Journal of Chemistry 43, n.º 35 (2019): 13850–56. http://dx.doi.org/10.1039/c9nj03427g.

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Poyet, Stéphane, Gaëtan Touzé, Jean-Luc Adia, Laurent Charpin y Sylvie Michel-Ponnelle. "A simple method to measure the isosteric energy of adsorption". Cement and Concrete Research 147 (septiembre de 2021): 106520. http://dx.doi.org/10.1016/j.cemconres.2021.106520.

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Tesis sobre el tema "Isosteric method"

Benchaabane, Mohammed-El Amine. "Etude des propriétés d'absorption de nouveaux absorbants innovants à base de matériaux hybrides poreux : application à la séparation de gaz". Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0323.

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Le contexte de cette étude concerne la séparation propène/propane, revendiquée comme un défi technique et énergétique dans l’industrie. La difficulté est principalement due à la forte similarité des propriétés physique et chimique des molécules en jeu. Pour y remédier, nous nous sommes intéressés à évaluer les performances d’adsorption vis-à-vis de ces gaz, en termes de capacité et de sélectivité d’un éventail de matériaux poreux (zéolithes et ZIFs). À cette fin, une étude complète, à la fois sur l’aspect thermodynamique et cinétique, des propriétés d’adsorption sur les zéolithes de type A, purement silicique et avec différents cations de compensation et des ZIFs-8, a été menée par un appareillage spécifique de microcalorimétrie d’adsorption qui permet de mesurer simultanément les isothermes d’adsorption et les énergies correspondantes. Ainsi pour les différents matériaux poreux ; l’affinité de l’adsorbant pour un gaz et la sélectivité par la méthode IAST ont été déterminées à partir des isothermes d’adsorption à l’équilibre des gaz purs. Les paramètres cinétiques ont été également calculés par application du modèle de Crank et LDF à partir des courbes de taux d’adsorption en fonction du temps. Dans la famille des ZIF-8, il est apparu que la cinétique d’adsorption des molécules d’adsorbant est essentiellement contrôlée par la taille d’ouverture des pores ainsi que sa flexibilité
The context of this study concerns the propene/propane separation, claimed as a technical and energetic challenge in the industry. The difficulty is mainly due to the strong similarity of the physical and chemical properties of the molecules involved. To address this issue, we have been interested in evaluating the adsorption performance towards these gases, in terms of capacity and selectivity of a range of porous materials (zeolites and ZIFs). To this end, a complete study, both on the thermodynamic and kinetic aspects, of the adsorption properties on type A zeolites, purely silicic and with different compensation cations and ZIFs-8, has been carried out by a specific adsorption microcalorimetry apparatus which allows to measure simultaneously the adsorption isotherms and the corresponding energies. Thus for the different porous materials; the affinity of the adsorbent for a gas and the selectivity by the IAST method were determined from the equilibrium adsorption isotherms of pure gases. Kinetic parameters were also calculated by application of the Crank and LDF model from the adsorption rate versus time curves. In the ZIF-8 family, it was found that the adsorption kinetics of the adsorbent molecules is mainly controlled by the pore opening size as well as its flexibility

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Hilding, Jenny Marie. "Characterization and Applications of Multiwalled Carbon Nanotubes". UKnowledge, 2004. http://uknowledge.uky.edu/gradschool_diss/303.

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Multiwalled carbon nanotubes (MWNTs) have attracted great interest during thelast decade due to their possession of a unique set of properties. In addition totheir strength, MWNTs have well defined morphologies, with large aspect ratiosand pores in the meso range, and intriguing transport properties, such as highelectrical and thermal conductivity.We are interested in how variations in the MWNT morphology affect areas ofpossible engineering applications. We have identified morphology as a criticalelement for the performance of MWNTs in engineering applications. Specificareas studied and reported here spans from surface adsorption and capillarycondensation, to dispersion and dispersion processes, and transport propertiesin relation to MWNT aspect ratio. This wide range of exploration is typicallyneeded for evaluating opportunities for new materials.MWNTs can be used in different types of adsorption systems and it should bepossible to tailor the MWNT morphology to suit a specific adsorption process.We found that the major part of butane, our model gas, adsorbs on the externalMWNT and only a small fraction ends up in the pores.The unusually large aspect ratio makes MWNTs ideal as fillers in polymermatrixes. Since MWNTs are electrically conductive, it is possible to align theMWNTs in the matrix before curing. We investigated the effect of AC-fields onaqueous MWNT dispersions and the possibility to align MWNTs in an electricalfield.It is also necessary to develop suitable dispersion methods, to enable theproduction of homogeneous dispersions and composites. We studied a numberof different mechanical dispersion methods and their effect on the MWNTmorphology.

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(8086712), Lee M. Stunkard. "UNVEILING ENZYMATIC MECHANISMS WITH MALONYL-THIOESTER ISOSTERES". Thesis, 2019.

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Malonyl-thioesters are reactive at the thioester carbonyl and the carboxylate moieties, as seen in acyl transfer or hydrolysis and decarboxylation. Enzymes use these reactive centers to perform different enzyme chemistry throughout metabolism. This enzyme chemistry coupled with the inherent reactivity of malonyl-thioesters makes structure-function studies difficult. When malonyl-thioesters are used for structure-function studies, it usually results in a hydrolyzed or decarboxylated product. There are examples, however, where this is overcome, many of which are discussed throughout this thesis. To overcome the inherent reactivity of malonyl-thioesters and enzymes, analogs have been synthesized to perform structure-function studies. Initial studies focused on altering the thioester carbonyl to limit hydrolysis and decarboxylation; however, these studies revealed the importance of retaining the thioester carbonyl to be positioned in the oxyanion hole. My thesis work focused on the synthesis, characterization, and use in structure-function studies of malonyl-thioester analogs that either preserve the thioester carbonyl or alter it to an ester or amide, and alter the carboxylate to a sulfonate or nitro group. After synthesizing the methylmalonyl-CoA analogs, we performed structure-function studies with methylmalonyl-CoA decarboxylase. This case study revealed the potential of these analogs to both inhibit decarboxylase activity and their use in structure-function studies to gain mechanistic insights. This successful study prompted us to continue these structure-function studies in enzymes with different chemistries such as an epimerase or bi-functional acyltransferase/decarboxylase. The widespread use of these methylmalonyl-CoA analogs also motivated us to add more malonyl-thioester analogs to our toolbox. I have preliminary data that these malonyl-thioester analogs inhibit β-keto-acyl-synthase III, an enzyme involved in fatty acid production in E. coli. This inhibition gives us confidence that these analogs will be useful in structure-function studies that will reveal answers to long standing mechanism and protein-protein interaction questions in the polyketide and fatty acid synthase field.

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Capítulos de libros sobre el tema "Isosteric method"

Mtori, Samia, Amira Touil y Fethi Zagrouba. "Desorption Isotherms and Thermodynamic Properties of Prickly Pear Seeds". En Advances in the Modelling of Thermodynamic Systems, 63–79. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-7998-8801-7.ch004.

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Sorption isotherms of prickly pear seeds were determined by static gravimetric method at temperatures 45º, 60º, and 70ºC, over a relative moisture range of 5-95%. Sorption isotherms are important to define dehydration limits of the product, estimate moisture content alterations under environment conditions, and to acquire moisture content values for safe storage. Four mathematical models were applied to analyze the experimental data. Equilibrium moisture contents of prickly pear seeds decreased with temperature increment at a constant value of relative humidity. The GAB model showed the best fitting to the experimental data. Isosteric heat and differential entropy, determined by applying the Clausius-Clapeyron and Gibbs-Helmholtz equations respectively, decreased strongly as the moisture content increased and could be well adjusted by an empirical exponential relationship. Enthalpy-entropy compensation theory is valid for the sorption of prickly pear seeds, in which the water sorption mechanism in seeds can be considered to be enthalpy controlled.

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Byerly-Duke, Jacob, Emily A. O’Brien, Brendan J. Wall y Brett VanVeller. "Thioimidates provide general access to thioamide, amidine, and imidazolone peptide-bond isosteres". En Methods in Enzymology. Elsevier, 2024. http://dx.doi.org/10.1016/bs.mie.2024.04.012.

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McCash, Elaine M. "Adsorption and desorption". En Surface Chemistry. Oxford University Press, 2001. http://dx.doi.org/10.1093/hesc/9780198503286.003.0003.

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This chapter examines adsorption and desorption. There are several possible outcomes when an atom or a molecule hits a surface, including elastic and inelastic scattering. However, the outcome of an atomic or a molecular collision that results in the retention of the molecule on the surface is of far greater importance to the study of surface chemistry. There are two types of interactions that can occur: physical adsorption (or physisorption) and chemisorption. In each case, the atom or molecule being adsorbed on the surface is usually described as the adsorbate; the adsorbing surface is usually termed the adsorbent or substrate. The chapter then looks at adsorption isotherms, before considering the measurement of heats of adsorption, isosteres, and desorption rates. It also discusses adsorption sites and geometries. Finally, the chapter highlights two methods which can provide information on surface chemical composition: auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS).

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Brinson, Robert G., Jennifer T. Miller, Jason D. Kahn, Stuart F. J. Le Grice y John P. Marino. "Applying Thymine Isostere 2,4-Difluoro-5-Methylbenzene as a NMR Assignment Tool and Probe of Homopyrimidine/Homopurine Tract Structural Dynamics". En Methods in Enzymology, 89–110. Elsevier, 2016. http://dx.doi.org/10.1016/bs.mie.2015.05.009.

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Actas de conferencias sobre el tema "Isosteric method"

Amel, Fedol y A. Cheriti. "Modelling the Water Sorption Isotherms of Warionia Saharae and determination of sorption heats and drying kinetics". En 21st International Drying Symposium. Valencia: Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/ids2018.2018.7669.

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The hygroscopic equilibrium of Warionia saharae was studied, which allowed getting an idea of the equilibrium water content relative to a given humidity. The results of this study made it possible to have the sorption curves. The results of this study made it possible to obtain the sorption curves necessary for know the storage conditions of the plant and the study of its drying kinetics. The static gravimetric method was used to determine sorption isotherms of Warionia saharae leaves at 30and 40 ◦C and in the range of water activity varying from 0.063 to 0.898. The Gab, Peleg models was found to be the most suitable for describing the sorption curves. The isosteric heat calculated by applying the Clausius–Clapeyron equation .The desorption isosteric heat was higher than the isosteric heat of adsorption and both decreased continuously with increasing of the equilibrium moisture content. The experimental results obtained allowed us to determine the temporal evolution of the drying kinetics as a function of the moisture content. The curve of the evolution of the water content as a function of time shows the absence of the phases product temperature and constant drying rate Keywords: Sorption isotherm, isosteric heats, modelling, kinetics, Warionia saharae.

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Luna-Flores, Mario, Mariana Gisela Peña-Juarez, Angélica Mara Bello-Ramirez, Javier Telis-Romero y Guadalupe Luna-Solano. "Moisture sorption isotherms and isosteric heat sorption of habanero pepper (Capsicum chínense) dehydrated powder". En 21st International Drying Symposium. Valencia: Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/ids2018.2018.7637.

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Moisture sorption isotherms of the habanero pepper powder were determined using the Dynamic Vapor Sorption (DVS) method at 20, 25, 35, 45 and 55 °C in a range of water activity from 0.10 to 0.90 at which the processes of drying, packing and storage of habanero pepper are developed. The sorption capacity decreased with increasing temperature at a given water activity and the sorption isotherms showed a sigmoid form (Type II). The hysteresis phenomenon was observed in the sorption isotherms at all temperatures studied and it was more pronounced at temperatures high. The experimental sorption curves were fitting to the GAB, BET and Oswin models. It was concluded that the models that best describe the adsorption and desorption data for habanero pepper dehydrated powder were the GAB and Oswin models. The isosteric heat of water sorption was calculated with the moisture content data in equilibrium. The desorption isotherms present a higher isosteric heat in relation to the adsorption isotherms. In both, the isosteric heat decreased as the moisture content increased. Keywords: Habanero pepper dehydrated powder; Convective drying; Moisture sorption isotherms; Mathematic models

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Collazos-Escobar, Gentil Andres, Nelson Gutiérrez-Guzmán, Henry Alexander Vaquiro-Herrera y Erika Tatiana Cortes-Macias. "Modeling sorption isotherms and isosteric heat of sorption of roasted coffee beans". En 21st International Drying Symposium. Valencia: Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/ids2018.2018.7668.

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The aim of this work was determine the sorption isotherms in roasted beans of specialty coffee at temperatures of 25, 30 and 40 °C and water activities between 0.1 and 0.8 using the dynamic dew point method. The experimental sorption data were modeled using 12 different equations to represent the dependence of equilibrium moisture content with aw and temperature. The net isosteric heat of sorption was determined from the experimental sorption data using the Clausius-Clapeyron equation. The Weibull model satisfactorily modeled the effect of the temperature on the hygroscopic equilibrium in roasted coffee beans (R2adj =0.902 and RMSE = 0.00550 kg·kg-1d.b.). The net isosteric heat of sorption increase with increased moisture content. Keywords: water activity; sorption properties; equilibrium moisture content; hygroscopicity

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Saha, Bidyut Baran, Kandadai Srinivasan, Anutosh Chakraborty, Khairul Habib, Ibrahim Ibrahim El-Sharkawy y Shigeru Koyama. "Adsorption Characteristics of Maxsorb-III + Methane Systems by Desorption Experiments". En ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42941.

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The adsorption isotherms and kinetics of gaseous methane onto highly porous activated carbon (Maxsorb-III) at temperatures ranging from 278 to 333 K and at different equilibrium pressures between 0.1 and 2.0 MPa have been experimentally measured by the desorption method unlike volumetric or thermo-gravimetric apparatus. The thermophysical properties such as skeletal density, BET surface area, pore size, pore volume and the total porosity of Maxsorb-III have been determined. The Dubinin-Astakhov (DA) and Langmuir isotherm models are found to fit well all of the experimental data within the experimental errors. The experimental isotherms and the computed isosteric heat of adsorption are compared with the measurements of similar specimens of activated carbon of other researchers, and found to be consistent. The present isotherm and isosteric heat data are useful for designing environmentally benign adsorption cooling and storage systems.

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Yang, Yun y Shimin Liu. "Quantification of Temperature-Dependent Sorption Kinetics in Shale Gas Reservoirs: Experiment and Theory". En SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205897-ms.

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Abstract A critical component of natural gas in organic-rich shales is adsorbed gas within organic matter. Quantification of adsorbed gas is essential for reliable estimates of gas-in-place in shale reservoirs. However, conventional high-pressure adsorption measurements for coal on the volumetric method are prone to error when applied to characterize sorption kinetics in shale-gas systems due to limited adsorption capacity and finer pores of shale matrix. An innovated laboratory apparatus and measurement procedures have been developed for accurate determination of the relatively small amount of adsorbed gas in the Marcellus shale sample. The custom-built volumetric apparatus is a differential unit composed of two identical single-sided units (one blank and one adsorption side) connected with a differential pressure transducer. The scale of the differential pressure transducer is ± 50 psi, a hundred-fold smaller than the absolute pressure transducer measuring to 5000 psi, leading to a significant increase in the accuracy of adsorption measurement. Methane adsorption isotherms on Marcellus shale are measured at 303, 313, 323 and 333 K with pressure up to 3000 psi. A fugacity-based Dubinin-Astakhov (D-A) isotherm is implemented to correct for the non-ideality and predict the temperature-dependence of supercritical gas sorption. The Marcellus shale studied displays generally linear correlations between adsorption capacity and pressure over the range of temperature and pressure investigated, indicating the presence of a solute gas component. It is noted that the condensed phase gas storage exists as the adsorbed gas on shale surface and dissolved gas in kerogen, where the solute gas amount is proportional to the partial pressure of that gas above the solution. To our best understanding, it is the first time to observe the contribution of dissolved gas to total gas storage. With adsorption potential being modeled by a temperature dependence expression, the D-A isotherm can successfully describe supercritical gas sorption for shale at multiple temperatures. Adsorption capacity remarkably decreases with temperature attributed to the isosteric heat of adsorption. Lastly, the wide applicability of the proposed fugacity-based D-A model is also tested for literature adsorption data on Woodford, Barnett, and Devonian shale. Overall, the fugacity-based D-A isotherm provides precise representations of the temperature-dependent gas adsorption on shales investigated in this work. The application of the proposed adsorption model allows predicting adsorption data at multiple temperatures based on the adsorption data collected at a single temperature. This study lays the foundation for accurate evaluation of gas storage in shale.

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