Academic literature on the topic 'BET adsorption isotherms'
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Journal articles on the topic "BET adsorption isotherms"
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Cascarini de Torre, Lydia Ethel, and Eduardo Jorge Bottani. "BET Adsorption Isotherm and Surface Heterogeneity." Collection of Czechoslovak Chemical Communications 57, no. 6 (1992): 1201–9. http://dx.doi.org/10.1135/cccc19921201.
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The BET adsorption isotherm is modified in order to take account of surface heterogeneity. The adsorption isotherm is obtained following the statistical mechanics formalism, proposed by Steele, and the effect of surface heterogeneity is limited to the first layer. A Gaussian adsorption energies distribution function is used to describe surface heterogeneity. The variations of the C parameter, multilayer formation and the inversion of adsorption isotherms are analysed.
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Agarwal, Ajay K., Mahendra S. Kadu, Chandrashekhar P. Pandhurnekar, and Ishwardas L. Muthreja. "Equilibrium isotherm studies for the sorption of Nickel ions onto coal fly ash." Environment Conservation Journal 15, no. 1&2 (June 18, 2014): 153–59. http://dx.doi.org/10.36953/ecj.2014.151220.
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The objective of the present study was to study equilibrium isotherm for the sorption of Nickel ions onto coal fly ash. In this study, BET adsorption isotherm was found to be best fitted among Langmuir, Freundlich, BET, Temkin and Harkins Jura adsorption isotherms using lest square fit method. The best fit adsorption isotherm is assessed by the linear coefficient of determination (R2) and non-linear Chi-square test. The theoretical value of qe calculated from the best fit linear equation of each adsorption isotherm and the experimental values of qe (0.08) are plotted against Ce, to compare the experimental and Theoretical value of qe.
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Bakaev, V. A., and W. A. Steele. "The Characteristic Curve in Physical Adsorption." Adsorption Science & Technology 10, no. 1-4 (March 1993): 123–36. http://dx.doi.org/10.1177/0263617499010001-411.
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The concept of the characteristic curve in physical adsorption and the rule of its temperature invariance is traced from the potential theory of adsorption by Polanyi to the Frenkel–Halsey–Hill equation, the theory of volume filling of micropores by Dubinin et al. and the theory of adsorption on heterogeneous surfaces. A computer simulation of an irregular atomic configuration at the surface of amorphous carbon is presented. In the submonolayer region, the isotherms of argon adsorption simulated on that surface are shown to correspond to the Freundlich equation and are close to the experimental isotherms on a diamond dust sample. Simulated isosteric heats of adsorption are also reasonably close to the experimental data for argon on a real carbon black. The BET C constant for the simulated isotherm is lower than for the real isotherm on untreated carbon black. However, the isotherms at two temperatures can be described by one absolute isotherm of adsorption.
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Mashile, Geaneth Pertunia, Kgokgobi Mogolodi Dimpe, and Philiswa Nosizo Nomngongo. "A Biodegradable Magnetic Nanocomposite as a Superabsorbent for the Simultaneous Removal of Selected Fluoroquinolones from Environmental Water Matrices: Isotherm, Kinetics, Thermodynamic Studies and Cost Analysis." Polymers 12, no. 5 (May 12, 2020): 1102. http://dx.doi.org/10.3390/polym12051102.
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The application of a magnetic mesoporous carbon/β-cyclodextrin–chitosan (MMPC/Cyc-Chit) nanocomposite for the adsorptive removal of danofloxacin (DANO), enrofloxacin (ENRO) and levofloxacin (LEVO) from aqueous and environmental samples is reported in this study. The morphology and surface characteristics of the magnetic nanocomposite were investigated by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption–desorption and Fourier transform infrared spectroscopy (FTIR). The N2 adsorption–desorption results revealed that the prepared nanocomposite was mesoporous and the BET surface area was 1435 m2 g−1. The equilibrium data for adsorption isotherms were analyzed using two and three isotherm parameters. Based on the correlation coefficients (R2), the Langmuir and Sips isotherm described the data better than others. The maximum monolayer adsorption capacities of MMPC/Cyc-Chit nanocomposite for DANO, ENRO and LEVO were 130, 195 and 165 mg g−1, respectively. Adsorption thermodynamic studies performed proved that the adsorption process was endothermic and was dominated by chemisorption.
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Chen, Qing, Yuanyuan Tian, Peng Li, Changhui Yan, Yu Pang, Li Zheng, Hucheng Deng, Wen Zhou, and Xianghao Meng. "Study on Shale Adsorption Equation Based on Monolayer Adsorption, Multilayer Adsorption, and Capillary Condensation." Journal of Chemistry 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/1496463.
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Shale gas is an effective gas resource all over the world. The evaluation of pore structure plays a critical role in exploring shale gas efficiently. Nitrogen adsorption experiment is one of the significant approaches to analyze pore size structure of shale. Shale is extremely heterogeneous due to component diversity and structure complexity. Therefore, adsorption isotherms for homogeneous adsorbents and empirical isotherms may not apply to shale. The shape of adsorption-desorption curve indicates that nitrogen adsorption on shale includes monolayer adsorption, multilayer adsorption, and capillary condensation. Usually, Langmuir isotherm is a monolayer adsorption model for ideal interfaces; BET (Brunauer, Emmett, Teller) adsorption isotherm is a multilayer adsorption model based on specific assumptions; Freundlich isotherm is an empirical equation widely applied in liquid phase adsorption. In this study, a new nitrogen adsorption isotherm is applied to simultaneously depict monolayer adsorption, multilayer adsorption, and capillary condensation, which provides more real and accurate representation of nitrogen adsorption on shale. In addition, parameters are discussed in relation to heat of adsorption which is relevant to the shape of the adsorption isotherm curve. The curve fitting results indicate that our new nitrogen adsorption isotherm can appropriately describe the whole process of nitrogen adsorption on shale.
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Ribeiro, Luciana C., José M. C. da Costa, and Marcos R. A. Afonso. "Hygroscopic behavior of lyophilized acerola pulp powder." Revista Brasileira de Engenharia Agrícola e Ambiental 20, no. 3 (March 2016): 269–74. http://dx.doi.org/10.1590/1807-1929/agriambi.v20n3p269-274.
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ABSTRACT Powder products are characterized by their practicality and long life. However, fruit powders have high hygroscopicity and tend to agglomerate due to its hydrophilic nature. The isotherms of equilibrium moisture content apply to the study of dehydrated food preservation potential. Acerola is a nutritionally rich fruit, with great economic and industrial potential. The objective of this study was to analyse acerola powder adsorption isotherms obtained by lyophilization and characterize the powder obtained from lyophilized acerola pulp. Analysis of hygroscopicity, solubility and degree of caking were performed. Isotherms were represented by the mathematical models of GAB, BET, Henderson and Oswin, at temperatures of 25, 35 and 45 °C. According to the results, the obtained powder showed hygroscopicity of 5.96 g of absorbed water 100g-1 of solids, solubility of 95.08% and caking of 14.12%. The BET model showed the best fit to the adsorption isotherms of the acerola pulp powder obtained by lyophilization. The obtained isotherm was of type III, with a "J" shape. There was an inversion of the effect of temperature on the isotherms of acerola powders.
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Yu, Wei, Kamy Sepehrnoori, and Tadeusz W. Patzek. "Modeling Gas Adsorption in Marcellus Shale With Langmuir and BET Isotherms." SPE Journal 21, no. 02 (April 14, 2016): 589–600. http://dx.doi.org/10.2118/170801-pa.
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Summary Production from shale-gas reservoirs plays an important role in natural-gas supply in the United States. Horizontal drilling and multistage hydraulic fracturing are the two key enabling technologies for the economic development of these shale-gas reservoirs. It is believed that gas in shale reservoirs is mainly composed of free gas within fractures and pores and adsorbed gas in organic matter (kerogen). It is generally assumed in the literature that the monolayer Langmuir isotherm describes gas-adsorption behavior in shale-gas reservoirs. However, in this work, we analyzed four experimental measurements of methane adsorption from the Marcellus Shale core samples that deviate from the Langmuir isotherm, but obey the Brunauer-Emmett-Teller (BET) isotherm. To the best of our knowledge, it is the first time to find that methane adsorption in a shale-gas reservoir behaves similar to multilayer adsorption. Consequently, investigation of this specific gas-desorption effect is important for accurate evaluation of well performance and completion effectiveness in shale-gas reservoirs on the basis of the BET isotherm. The difference in calculating original gas in place (OGIP) on the basis of both isotherms is discussed. We also performed history matching with one production well from the Marcellus Shale and evaluated the contribution of gas desorption to the well's performance. History matching shows that gas adsorption obeying the BET isotherm contributes more to overall gas recovery than gas adsorption obeying the Langmuir isotherm, especially at early time in production. This work provides better understanding of gas desorption in shale-gas reservoirs and updates our current analytical and numerical models for simulation of shale-gas production.
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Jabłoński, Maciej. "BET-Type Adsorption Isotherms for Gaseous Mixtures." Adsorption Science & Technology 23, no. 6 (July 2005): 487–96. http://dx.doi.org/10.1260/026361705774859875.
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A formalism for describing the adsorption of gaseous mixtures at solid surfaces was derived as an extension of the BET theory. The following additional assumptions were made; the composition of all the adsorbed layers is the same and interaction occurs between the component molecules in the adsorbed layers. The proposed equations were compared with the experimental data obtained from measurements of the adsorption of an acetone—methanol mixture onto N-type active carbon.
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Ge, Mingliang, Xubin Wang, Mingyi Du, Guodong Liang, Guoqing Hu, and Jahangir S.M. "Adsorption Analyses of Phenol from Aqueous Solutions Using Magadiite Modified with Organo-Functional Groups: Kinetic and Equilibrium Studies." Materials 12, no. 1 (December 28, 2018): 96. http://dx.doi.org/10.3390/ma12010096.
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Organically-modified magadiite (MAG–CTAB–KH550) was synthesized via ion-exchange method and condensation reaction in the presence of pure magadiite (MAG), cetyltrimethylammonium bromide (CTAB) and γ-aminopropyltriethoxysilane (KH550) in aqueous solution in this research. This new adsorbent material was studied using scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and N2 adsorption/desorption isotherms process. It was found that the MAG–CTAB–KH550 has high Brunaur-Emmet-Teller (BET) specific surface area and mesoporous pore size distribution which enhanced its ability to remove phenol in aqueous solution; and, the value of pH has a relatively large impact on the adsorption behavior of the sorbent. Finally, the adsorptive behavior of the mesoporous material on phenol was followed pseudo-second-order kinetic adsorption model. In contrast, the adsorption equilibrium isotherm was better performed Langmuir isotherm model than the Freundlich isotherm model; in addition, the results also showed that the MAG–CTAB–KH550 had a better adsorption capacity and removal efficiency than MAG.
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Luo, Li Jun, Ping Bao Ban, Xue Jiao Huang, and Jun Hong Li. "Functionalized Mesporous Silica with Ethylenediamine for Removal of Pb(II)." Applied Mechanics and Materials 395-396 (September 2013): 610–14. http://dx.doi.org/10.4028/www.scientific.net/amm.395-396.610.
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Amine-functionalized mesporous silicas ((referred as NH2MS)) were synthesized by grafting with ethylenediamine. The obtained materials have been characterized by N2 adsorption desorption measurement (BET). Adsorption behaviors of the adsorbent for lead (containing effects factors, kinetics, isotherms, thermodynamics) were investigated. The result indicated that the obtained particles possessed mesoporous structrure. The Pb (II) adsorption isotherm and kinetic data fit Freundlich model and the pseudo second-order kinetic model respectively. the adsorption of Pb (II) onto NH2-MS was an enothermic nature.
Dissertations / Theses on the topic "BET adsorption isotherms"
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Biggs, Georgina Aimee. "The Onsager heat of transport at the liquidvapour interface of p-tert-butyltoluene." Thesis, University of Canterbury. Chemistry, 2007. http://hdl.handle.net/10092/1386.
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The Onsager heat of transport for p-tert-butyltoluene was measured, as part of a series of preliminary experiments towards the determination of the importance of temperature gradients on the air-sea flux of carbon dioxide. The results presented in this thesis imply that the temperature gradient is a major contributor to the magnitude of the air-sea flux. The heat of transport has been measured for the p-tert-butyltoluene system by measuring stationary-state pressure changes for known temperature differences on the vapour side of the interface. At the pressure ranges used the number of mean free paths was always outside the Knudsen zone, but the values of Q* were approximately 100 % of the latent heat of vaporisation. Departures from linearity of plots of P against ΔT are attributed to temperature jumps at the surface of the dry upper plate. Both the results taken for p-tert-butyltoluene and the earlier results for water from this laboratory fit to a Type III BET isotherm, where the c parameter is not constant. They also reveal the importance of the temperature gradient in determining the value of the thermal accommodation coefficient, and provide a new method of measuring thermal accommodation coefficients for a variety of surfaces and vapours
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Borsato, Francimeiri Piva. "Avaliação do mecanismo de adsorção do metronidazol em carvão ativado da casca do coco babaçu." Universidade Estadual do Oeste do Paraná, 2018. http://tede.unioeste.br/handle/tede/3988.
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This work has evaluated the adsorption capability of three coal produced in the Universidade Estadual do Oeste do Paraná (tilapia bone residual coal, soybean bark coal and chestnut from Pará) and other kind of coal commercially obtained (babaçu coconut pealing coal) to remove the metronidazole from aqueous solution. The coal which better absorbed the metranidazole was the babaçu coconut peal one (CCCB) with temperature from 40ºC, 150 rpm of stirring and with no pH adjustment. Thus, the kinetic tests were performed by using the SOTAX dissolution apparatus, with 1000 mL of metronidazole solution, varying the concentration (200, 400, 650 and 850 mg/ L) and the temperature (30, 40, 45ºC), 1 g of the coal and 150 rpm of stirring. The equilibrium time observed was around 20 hours and in the first 4 hours a bigger amount of metranidazole was adsorbed, this inicial amount corresponds to the metranidazole adsorption in the outer layer of the CCCB. The results obtained from the adsorption kinetics were described by the intraparticule diffusion in which were verified the appearing of four well defined regions corresponding to the adsorption in the outer layer, in the macropores, in the CCCB mesopores and the equilibrium, respectively. In the equilibrium studies, were presented two adsorption mechanisms: monolayer and multilayer with increasing concentration of the adsorbate, corresponding to the hybrid model of Langmuir + BET. The removing process of metranidazole by using CCCB became economically viable due to the low cost in the obtention or production of the adsorbent, the easily extracetion of the babaçu coconut biomass and the excellent capability of maximum adsorptive to the metranidazole.
Neste trabalho, avaliou-se a capacidade de adsorção de três carvões produzidos na Universidade Estadual do Oeste do Paraná (carvão do resíduo ósseo de tilápia, carvão da casca da soja e o carvão da casca da castanha do Pará) e um carvão obtido comercialmente (carvão da casca do coco babaçu) para remoção do antibiótico metronidazol de solução aquosa. O carvão que melhor adsorveu o metronidazol foi o carvão da casca do coco babaçu (CCCB) com temperatura de 40ºC, 150 rpm de agitação e sem ajuste de pH. Dessa forma, os testes cinéticos foram realizados com o auxílio de um dissolutor (Sotax), utilizando 1000 mL de solução de metronidazol, variando a concentração (200, 400, 650 e 850 mg L-1) e a temperatura (30, 40 e 45ºC), 1 g do carvão e 150 rpm de agitação. O tempo de equilíbrio observado foi de aproximadamente 20 horas e nas primeiras 4 horas uma maior quantidade de metronidazol foi adsorvida, essa quantidade inicial corresponde à adsorção do metronidazol na camada externa do CCCB. Os dados obtidos a partir da cinética de adsorção foram descritos pelo modelo de difusão intrapartícula, no qual verificou-se o aparecimento de quatro regiões bem definidas correspondendo respectivamente a adsorção na camada externa, nos macroporos, nos mesoporos do CCCB e por último o equilíbrio. No estudo de equilíbrio, apresentou dois mecanismos de adsorção: monocamada e multicamadas com o aumento da concentração do adsorvato, correspondendo ao modelo híbrido de Langmuir+ BET. O processo de remoção de metronidazol utilizando o CCCB é economicamente viável visto o baixo custo na obtenção ou fabricação do adsorvente por ser extraído da biomassa do coco babaçu, além de possuir uma excelente capacidade máxima adsortiva para o antibiótico estudado.
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Yeboah, Siegfried Kwame. "An integrated packed bed-oscillating heat pipe system for energy efficient isothermal adsorption processes." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/48342/.
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Energy use in buildings accounts for a large portion of global and regional energy demand and energy-related CO2 emissions. To steer the world towards a low carbon future, the development of new and more efficient technologies is required. In hot and humid climates, the high latent heat loads results in uncomfortable and unhealthy indoor environments, accounting for 30% to 50% of standard air conditioning energy requirements. Physical adsorption of water vapour on solid desiccants is found to offer an energy efficient alternative to conventional dehumidification process using standard air conditioning systems. However, the isosteric heat of adsorption released increases the surface vapour pressure of the solid desiccants resulting in a decreased adsorption capacity. In packed beds of solid desiccants, this heat of adsorption increases the bed temperature, exit air temperature and exit air humidity ratio subsequently imposing an increased cooling load requirement and high energy requirement in the regeneration of the solid desiccants. In literature, several approaches used in removing in situ the heat of adsorption released in packed bed systems were fraught with several limitations. To this end, an integrated packed bed-oscillating heat pipe (OHP) system was proposed. The concept was for the evaporator of the OHP to remove the heat of adsorption generated by the packed bed and reject at its condenser towards an energy efficient isothermal adsorption process. To achieve this, theoretical investigations of the individual systems and the integrated systems preceded experimental testing of a rig set up in the laboratory. For the theoretical studies, the OHP was helically coiled at both ends, filled with ethanol, methanol and water working fluids respectively at 50% volume fraction and numerically investigated using the Eulerian Volume of Fluid (VOF) model in ANSYS Fluent R15.0. The packed bed on the other hand was configured as a Heggs et al (1994) Z-type flow arrangement for enhanced radial flow using the Porous Media model in ANSYS Fluent R15.0 set up with the properties of Silica Gel. ANSYS Fluent R15.0 System Coupling limitations led to the development of mathematical models for the prediction of the integrated system performance. The experimental investigations were in line with the theoretical only in this case the optimum working fluid, deionized water, was used as the main working fluid in the helically coiled OHP (HCOHP). The results showed reasonable agreement between the performance of the numerical model and experimental prototype. The HCOHPs were capable of passively removing heat from the packed bed systems. Mean bed temperature reduction between the integrated packed bed-HCOHP system and corresponding individual packed bed configurations were about 5.61°C, 9.48°C and 10.14°C respectively for the large annulus (LAPB), medium annulus (MAPB) and small annulus (SAPB) packed bed configurations. Average packed bed outlet temperature reductions of about 6.61°C, 9.19°C and 6.29°C were also achieved for the respective configurations. A validation of the theoretical model showed average temperature difference of about 5.60°C between the experimental prototype of the integrated system and results predicted using experimental packed bed temperature data and HCOHP thermal resistance. Compared to other similar systems in literature, the integrated packed bed-HCOHP system showed capacity to passively remove significant amounts of the heat of adsorption released in silica gel packed beds towards isothermal adsorption.
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Tetteh, Emmanuel. "Adsorption of Pharmaceuticals and Endocrine Disrupting Compounds using Unmodified and Surfactant Modified Palygorskite-Montmorillonite Clay Particles in Batch and Fixed Bed Column Modes." Miami University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=miami1543583842195458.
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Freire, Flavio Bentes. "Tratamento anaeróbio de efluente contendo pentaclorofenol em reator de leito fluidificado." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-04092007-171136/.
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Remoções quase totais de clorofenóis, por processos anaeróbios, já foram atingidas mediante elevada concentração de matéria orgânica e um número considerável de fontes de carbono. Porém, é necessário que se investigue o desempenho dos reatores submetidos a condições menos idealizadas. Este trabalho apresenta o desenvolvimento de uma metodologia para avaliar um reator anaeróbio de leito fluidificado (RALF) como etapa de pré-tratamento de substrato sintético contendo pentaclorofenol (PCP). Para isso, foram adotadas as seguintes condições experimentais: fonte única de carbono; concentração reduzida de matéria orgânica; biomassa não previamente adaptada, e menores tempos de detenção hidráulica. Para cumprir o objetivo citado, foram desenvolvidos dois reatores, com 2,2 e 16 litros, respectivamente, e foram realizadas etapas de avaliação de materiais suporte, estudo de diversas interações (partícula/fluido, partículas fluido, biopartícula/fluido e biopartículas/fluido), e análise do desempenho do RALF sem PCP e com PCP. Os materiais suporte escolhidos foram a alumina, o basalto e o carvão ativado granular, todos com diâmetros próximos a 3 mm. Eles foram avaliados em ensaios de caracterização física, de microscopia eletrônica de varredura, de fluidodinâmica e de análise de imagens. O carvão apresentou os melhores resultados e foi escolhido para a continuidade do trabalho. As interações foram analisadas através de ensaios fluidodinâmicos, isotermas de adsorção, dentre outros. Nas condições experimentais utilizadas, a biomassa aumentou a densidade da partícula, fato que foi comprovado pelos ensaios para determinação da velocidade mínima de fluidificação, de expansão e porosidade do leito, e também de velocidade terminal da partícula isolada. As isotermas de adsorção demonstraram que a presença de matéria orgânica diminuiu em 9% a adsorção do PCP. O RALF apresentou um comportamento satisfatório no período de operação sem PCP. Nos 105 dias de operação, a eficiência média de remoção de DQO ficou quase sempre superior a 90%, e os outros parâmetros de monitoramento de desempenho apresentaram valores típicos, indicando estabilidade no processo. A presença de PCP no sistema, nas concentrações utilizadas, não alterou a qualidade da biomassa presente, e nem os parâmetros de monitoramento de desempenho, como DQO, alcalinidade, pH e ácidos voláteis. Mesmo sob condições menos idealizadas, foi observado um desempenho satisfatório do reator na remoção do PCP. Em concentrações variando de 1 a 6 mg/L, foram observadas eficiências médias de remoção de 93% e 70%, respectivamente, para os 80 dias de operação nessas condições. Diante dos resultados obtidos, foi possível concluir que a remoção de PCP em um RALF pode ser atingida mediante condições operacionais mais simples.The almost total removal of chlorophenols by anaerobic processes has been achieved under high concentrations of organic matter and a considerably large number of carbon sources. However, it is necessary to investigate the performance of such reactors under less idealized conditions. The present work shows the development of a new methodology for evaluating the use of an anaerobic fluidized bed reactor (AFBR) in the pretreatment step of a synthetic substrate containing pentachlorophenol (PCP). In order to do that, the following experimental conditions were used: a single source of carbon; reduced concentrations of organic matter; non-previously adapted biomass, and smaller hydraulic retention times. To achieve the main objective, two reactors, one having a volume of 2.2 L and the other one, 16 L, were especially designed; evaluation steps of support material and the study of several interactions (particle/fluid, particles/fluid, bioparticle/fluid, bioparticles/fluid) were carried out, and the performance of the AFBR with and without PCP was analyzed. The three support materials employed were alumina, basalt and granular activated carbon, all having average diameters of 3 mm. These materials were evaluated through physical characterization methods, microscopy, hydrodynamic and image analyses. The activated coal showed the best results and was exclusively employed in the remainder of the work. The interactions were analyzed by hydrodynamics and adsorption isotherms, to name but a few. Under the experimental conditions employed, the biomass made the particle density increase, a fact that was verified in the determination of the minimum fluidization velocity, the bed porosity and expansion as well as the terminal velocity of isolated particles. The adsorption isotherms showed a decrease of 9% in PCP absorption due to the existence of organic matter. The AFBR showed satisfactory results during the operation without PCP. In the 105 days of operation, the average efficiency of COD removal remained almost always over 90%, while the other performance monitoring parameters remained at typical values, indicating the process stability. The presence of PCP under the concentrations used in the system did not seem to affect neither the quality of the biomass nor the performance monitoring parameters, like COD, alkalinity, pH and volatile acids. Even under less idealized conditions, the reactor showed good performance in removing PCP. The average efficiencies of removal attained around 93% and 70% for concentrations of 1 to 6 mg/L respectively. These concentration levels were kept during 80 days. In view of the results obtained, it is possible to conclude that reasonably good efficiency of PCP removal in AFBR can be attained under simpler operational conditions.
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Melo, Diego de Quadros. "LIGNOCELLULOSIC ACTIVATED WASTE USE ADSORBENTS IN TOXIC METALS IONS REMOVAL: BATCH AND COLUMN STUDIES USING DESING EXPERIMENTAL." Universidade Federal do CearÃ, 2015. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=17236.
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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgicoThe tururi and buriti fibers, and the castor bean stalks are extremely efficient to sorption of metal ions from aqueous solutions. In this study, the adsorbents were activated with different concentrations of alkali solutions (5, 7, 10 and 15% w/v). The materials were characterized by analytical techniques as infrared, X-ray Diffraction (XRD) and Thermogravimetry analysis. The infrared spectra revealed that associated groups to macromolecules of hemicellulose and lignin after alkaline activation have less intensity compared to the initial samples. The XRD revealed, that after castor bean stalks alkaline activation, the presence of the cellulose type II peaks, which did not occur with tururi and buriti fibers. The fluorescence X-ray data showed that the cations present in the initial adsorbents, K+ and Ca2 + are exchanged by Cu (II), Ni (II), Cd (II) and Pb (II) in the sorption process. Studies of the influences of variables: mass of adsorbent; agitation rate; the initial pH and concentration using a fractional factorial design 24-1 demonstrated that all variables affect the response (adsorption capacity mg g-1). As a result for a larger value of qtotal, conditions were observed while maintaining the pH at 5.5; mass of the adsorbent 50 mg; agitation at 200 rpm and the initial concentration: 500 mg L-1. The adsorption kinetics revealed fast adsorption process, about 30 minutes, and good fitting to pseudo-second-order theoretical model to all adsorption process studied. Intraparticle diffusion models as Weber-Morris and Boyd were testes in order to study the limiting steps of the process.The results showed that for tururi and buriti fibers (with the exception of nickel ions) the rate-limiting step is not the intraparticle diffusion, while for the castor bean stalks, it was found that the rate-limiting step of the process is the intraparticle diffusion. The study of monoelement and multielement systems were performed at pH 5.5, initial concentrations from 20-500 mg L-1, which the experimental data were fitted to the Langmuir, Freundlich and Sips theoretical models. The tururi fibers adsorption capacities (mg g-1) in monoelementar and multielement system follows the order Pb (188.79)> Cd (92.20)> Cu (32.82)> Ni (22.23) and Cd (77.53)> Pb (43.93)> Cu (24.99)> Ni (19.51), respectively. Buriti fibers adsorption capacities (g-1 mg) in monoelementar and multielement systems follows the order of Cu (143.1)> Pb (112.1)> Ni (103.7)> Cd (86.33) and Pb (69.12)> Cu (49.28)> Ni (45.10)> Cd (24.95), respectively. Castor bean stalks adsorption capacities (g-1 mg) in in monoelementar and multielement systems follows the order of Pb (175.1)> Cd (124.8)> Ni (111.1)> Cu (89.23) and Cu (56.78)> Pb (55.82)> Cd (44.72)> Ni (43.48), respectively. The results showed a better fit for the Sips model, relating to a heterogeneous adsorption. Fixed bed studies using castor bean stalks checking the influence of variables adsorbent flow (1, 2 and 3 mL min-1), the height of the column (5, 7 and 10 cm) and initial concentration (100 , 200, 300 mg L-1) by the Box-Behnken planning revealed that there were no influence between the variables in the studied. The breakthrough curves were well fitted to the Thomas model. The study in real effluent with Cu (II) (galvanoplastic sector) was carried out using the optimized condition: flow (1 ml min-1); bed height (10 cm) initial concentration: (245.5 mg L-1) and it was found adsorption capacity of 32.42 mg g-1. The mamoneira stalks adsorbent was used for five cycles to verify their potential reuse, and it was found no significant efficiency losses.
As fibras tururi, buriti e talos da mamoneira sÃo resÃduos lignocelulÃsicos extremamente eficientes na sorÃÃo de metais de soluÃÃes aquosas. Neste trabalho, eles foram ativados com diferentes concentraÃÃes de soluÃÃes alcalinas (5, 7, 10 e 15% m/v). Os materiais foram caracterizados pelas tÃcnicas analÃticas de Infravermelho, DifraÃÃo de Raios-X (DRX) e Termogravimetria. Os espectros de infravermelho revelaram que os grupos associados Ãs macromolÃculas de hemicelulose e lignina diminuem em intensidade ou desaparecem apÃs a ativaÃÃo alcalina. Os DRX revelaram que apÃs a ativaÃÃo alcalina, os talos da mamoneira apresentaram picos de celulose tipo II, o que nÃo ocorreu com as fibras de tururi e buriti. O dados de FluorescÃncia de Raios-X revelaram que os cÃtions presentes nos adsorventes como Na(I) e Ca(II) sÃo trocados pelos Ãons Cu(II), Ni(II), Cd(II) e Pb(II) no processo de sorÃÃo. Os estudos das influÃncias das variÃveis: massa do adsorvente; taxa de agitaÃÃo; pH e concentraÃÃo inicial utilizando planejamento experimental fracionÃrio 24-1 demostrou que todas as variÃveis afetaram a resposta (capacidade de adsorÃÃo mg g-1). Como resultado para um maior valor de qtotal, as condiÃÃes observadas foram mantendo o pH em 5,5; massa do adsorvente em 50 mg; taxa de agitaÃÃo em 200 rpm e concentraÃÃo inicial 500 mg L-1. A cinÃtica de adsorÃÃo revelou rÃpida adsorÃÃo, cerca de 30 minutos em geral, seguindo o modelo de pseudo-segunda ordem em todos os processos adsortivos. Modelos de difusÃo intrapartÃcula como de Webber-Morris e Boyd foram estudados a fim de determinar as etapas limitantes do processo. Os dados evidenciaram que para as fibras de tururi e buriti (com exceÃÃo dos Ãons nÃquel) a etapa limitante da velocidade nÃo à a difusÃo intraporo, enquanto para os talos de mamoneira foi verificado que a etapa limitante do processo à a difusÃo intrapartÃcula. O estudo com sistema monoelementar e multielementar foi realizado em pH 5,5, concentraÃÃes variando de 20-500 mg L-1, nos quais os dados foram aplicados aos modelos de Langmuir, Freundlich e Sips. As capacidades de adsorÃÃo (mg g-1) em sistema monoelementar e multielementar das fibras de tururi segue a ordem Pb(188,79)> Cd(92,20)> Cu(32,82)> Ni(22,23) e Cd(77,53)> Pb(43,93)> Cu(24,99)> Ni(19,51), respectivamente. As capacidades de adsorÃÃo (mg g-1) das fibras de buriti em sistema monoelementar e multielementar segue a ordem Cu(143,1)> Pb(112,1)> Ni(103,7) > Cd(86,33) e Pb(69,12)> Cu(49,28)> Ni(45,10)> Cd(24,95), respectivamente. As capacidades de adsorÃÃo (mg g-1) dos talos de mamoneira em sistema monoelementar e multielementar segue a ordem Pb(175,1)> Cd(124,8)> Ni(111,1)> Cu(89,23) e Cu(56,78)> Pb(55,82)> Cd(44,72)> Ni(43,48), respectivamente. Em geral, os resultados evidenciaram melhor aplicabilidade ao modelo de Sips, o qual prediz que os sÃtios disponÃveis para adsorÃÃo sÃo heterogÃneos. Em relaÃÃo ao estudo de adsorÃÃo em leito fixo utilizando talos de mamoneira, a verificaÃÃo da influÃncia das variÃveis: fluxo do adsorvente (1, 2 e 3mL min-1), altura da coluna (5, 7 e 10 cm) e concentraÃÃo inicial (100, 200, 300 mg L-1) pelo planejamento de Box-Behnken, revelou que nÃo hà influencia mutua entre as variÃveis no intervalo estudado. As curvas de ruptura experimentais foram bem aplicadas ao modelo teÃrico de Thomas. O estudo com efluente real de Ãons Cu (II) (setor galvanoplÃstico) utilizando a condiÃÃo otimizada: fluxo (1mL min-1); altura de leito (10 cm) e concentraÃÃo inicial: (245,5 mg L-1) obteve 32,42 mg g-1 de capacidade de adsorÃÃo O adsorvente talos de mamoneira foi utilizado por cinco ciclos para verificar seu potencial de uso, nÃo havendo perdas significativas de eficiÃncia.
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Neto, Vicente de Oliveira Sousa. "ModificaÃÃo QuÃmica da Casca do Coco Bruto (Cocos Nucifera) para RemoÃÃo de Cu(II) de Efluente SintÃtico e Industrial: Estudo de Isoterma de AdsorÃÃo, CinÃtica e Coluna de Leito Fixo." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8901.
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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgicoOs metais pesados sÃo conhecidos por serem altamente tÃxicos em baixÃssimas concentraÃÃes na Ãgua. Sendo assim, numerosos estudos tem sido dedicados à sua remoÃÃo a limites aceitÃveis do ponto de vista ambiental. Tais pesquisas se concentram, principalmente, no desenvolvimento de uma remoÃÃo eficiente e de baixo custo. Muitos mÃtodos tÃm sido propostos para remoÃÃo de metais pesados, por exemplo, precipitaÃÃo, membranas filtrantes, troca iÃnica e adsorÃÃo. A precipitaÃÃo à um dos mÃtodos que mais vem sendo utilizado embora seja um mÃtodo inadequado no que se refere a impactos ambientais por gerar resÃduos. A casca de coco oferece facilidade natural de ser encontrado e manejado, por isso à um dos materiais mais estudados para fins de reaproveitamento. Este trabalho se propÃe a fazer um estudo de adsorÃÃo de Cu+2 utilizando casca de coco modificado como adsorbente. As modificaÃÃes empregadas foram (a) por polimerizaÃÃo do formaldeÃdo em meio sulfÃrico; b) Tratamento com lÃquido iÃnico e c) EsterificaÃÃo por Ãcido multicarboxÃlicos e multifenÃlicos. Os modelos aplicados para o estudo de isotermas foram de Langmuir, Freundlich, Temkin e Dubinin âRaduschevich. Aplicando o modelo de Langmuir no estudo de adsorÃÃo de Cu(II) no adsorbente modificado BCFB a capacidade mÃxima de adsorÃÃo qm e a constante KL foram 125 mg/g e 1,11x10-1 L.mg-1 para o Cu+2 . Para os adsorbentes BC/LI e BCTÃnico o valor de qm foram 64,5 e 99mg.g-1 , respectivamente enquanto o valor de KL foram 5,3x10-2 e 5,6x10-2 , respectivamente . O modelo cinÃtico que melhor se ajustou ao fenÃmeno foi o de segunda ordem. Os resultados obtidos mostraram que a casca de coco quimicamente modificado à um potencial adsorbente para remoÃÃo de Cu+2. O estudo de coluna foi empregado para verificar a desempenho do adsorbente quando se emprega efluente industrial. Nas condiÃÃes empregadas neste estudo a modificaÃÃo com Ãcido tÃnico foi a que teve melhor desempenho de remoÃÃo. Destaca-se tambÃm a capacidade de reutilizaÃÃo do adsorbente que promove uma diminuiÃÃo do custo operacional quando à considerada sua aplicabilidade numa escala industrial.
The heavy metals are known to be highly toxic at very low concentrations in water. At this point, numerous studies have been dedicated to their removal to acceptable limits of an environmental point of view. Such researches are focused mainly in developing an efficient removal and low cost. Many methods have been proposed for removing heavy metals, for example, precipitation, membrane filtration, ion exchange and adsorption. The precipitation is one method that has been used more although an inappropriate method regarding the environmental impact for generating residues. The bagasse, coconut offers natural facility to be found and handled, so it is one of the most studied materials for reuse. This paper aims to make a study of adsorption of Cu 2+ using bagasse as adsorbent modified coconut. The modifications were employed (a) by polymerization of formaldehyde in sulfuric acid medium, b) treatment with ionic lÃguido c) Esterification acid and multicarboxÃlicos multifenÃlicos. The models applied to the study of isotherms were Langmuir, Freundlich, Temkin and Dubinin-Raduschevich. Applying the model in the study of Langmuir Adsorption of Cu (II) adsorbent modified BCFB the maximum adsorption capacity qm and kL were contained 125 mg.g-1 and 1.11 x10-2L.mg for Cu +2. For adsorbentes BC / LI and BCTÃnico the qm value were 64.5 and 99mg.g-1 respectively as kL value were 5.3 x10-2 5.6 x10-2 respectively. The kinetic model that best fit the phenomenon was the second order. The results showed that the coconut coir chemically modified is a potential adsorbent for removing Cu2+. The study column was used to verify the performace of the adsorbent when employing industrial effluent. Under the conditions employed in this study was modified with tannic acid that had shown the best removal performance desempenho removal. Also the reusability of the adsorbent is remarkable since it promotes a lowering cost, considering its applicability on an industrial scale.
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Rodrigues, Alyne Freitas da Silva Bordalo. "Dessulfurização de butano líquido por adsorção mediante utilização de peneira molecular 13X." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-18012017-085923/.
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Atualmente, o tipo de propelente para produtos em aerossol mais usado no mundo é uma mistura de hidrocarbonetos leves (butano e propano - sendo o primeiro em maior proporção). Parte de seu processo de produção é a dessulfurização do butano líquido, através de adsorção em leito fixo usando peneiras moleculares 13X. A literatura científica não apresenta muitas publicações sobre o tema e considerando que a técnica de adsorção é fortemente dependente de dados experimentais para seu maior entendimento, é objetivo deste trabalho estudar este processo através do equilíbrio de adsorção, das curvas de ruptura e do desenvolvimento de um modelo matemático que represente o funcionamento de uma coluna de adsorção de leito fixo a temperatura constante. Obtiveram-se dados sobre o equilíbrio de adsorção por meio de ensaios em banho finito comparando-se a interação de diferentes compostos de enxofre com a peneira molecular 13X e o efeito da temperatura. Utilizou-se a técnica de cromatografia gasosa como método analítico para obtenção dos teores de compostos sulfurados e de hidrocarbonetos. O modelo de Langmuir apresentou bom ajuste aos dados experimentais. Avaliando-se a interação dos componentes sulfurados com a zeólita 13X, identificou-se diferenças significativas, sendo a maior em ordem decrescente: etil-mercaptana, n-propil-mercaptana e terc-butil-mercaptana, respectivamente. A dinâmica do processo de adsorção foi estudada através da obtenção das curvas de ruptura em leitos em escala laboratorial e piloto. Avaliaram-se as influências da variação da concentração de entrada da n-propil-mercaptana e da velocidade do fluido em leito fixo recheado com zeólitas 13X, mantendo os demais parâmetros constantes. Conforme esperado o aumento da concentração inicial reduz o tempo de ruptura, aumenta a quantidade total adsorvida pelo leito e não altera o comportamento da zona de transferência de massa (ZTM). Analisando-se a elevação da velocidade, nota-se também uma diminuição no tempo de ruptura e um aumento da ZTM. O modelo matemático apresentado considera os balanços de massa microscópicos aplicados ao leito, os fenômenos de transporte de massa com modelo de dispersão axial e transporte por convecção da fase líquida para a superfície da partícula e as isotermas de adsorção. As equações diferenciais parciais resultantes foram adimensionalizadas e resolvidas empregando-se o método de diferenças finitas, implementado por código Matlab®. A partir da simulação matemática das condições experimentais obtiveram-se os parâmetros de dispersão axial e de transferência de massa que possibilitaram uma boa reprodução do tempo de ruptura quanto do perfil da zona de transferência de massa para os experimentos em escala laboratorial e piloto.Currently, the kind of propellant for aerosol products most widely used in the world is a blend of light hydrocarbons (butane and propane - the first in greater proportion). Part of the production of propellant is the desulfurization of liquid-phase butane by molecular sieves 13X in a fixed bed. The scientific literature concerning the adsorption of the mercaptans using zeolite are scarce and considering that the adsorption technique is strongly dependent on experimental data for its better knowlegde, the aim of this work was to study this process by adsorption equilibrium, the breakthrough curves and the development of a mathematic model, simulation and comparison with the operation of a fixed-bed pilot and laboratory-scale column. Adsorption equilibrium parameters were obtained using finite bath experiment and comparing the interaction of different sulfur compounds with molecular sieve 13X and the temperature effect. It was used the gas chromatography as an analytical method in order to obtain the levels of hydrocarbons and sulfur compounds. The Langmuir model well fit the experimental data. Significant differences were identified in the interaction of the sulfur components with zeolite 13X. The major interactions of the sulfur components are in decreasing order: ethyl-mercaptan, n-propyl-mercaptan and terc-butyl-mercaptan. The dynamic of the adsorption process was studied by obtaining the breakthrough curves in laboratory and pilot scale. It was investigated the influence of the initial concentration of n-propyl mercaptan and the fluid velocity in a fixed bed packed with zeolite 13X keeping the other parameters constant. As it was expected, as the inlet sulfur concentration increases the break point time decrease, and enhances the total amount adsorbed by the bed. Analyzing the increase in velocity on the breakthroug profile, it was noted that also decreases the break point time and causes a greater decline of the curve resulting in greater ZTM and anticipating the bed saturation time. The model equations account the mass balance applied in the flowing liquid phase in the column, transport phenomena as the effect of axial dispersion and convection from liquid phase to the adsorbent surface and adsorption isotherm. Finite difference method was used to solve the dimensionless general partial differential equations and it was implemented by Matlab® software. From mathematical simulation of experimental conditions it were obtained the axial dispersion parameters and mass transfer coefficient which allowed a fair agreement in predicting break point time and the mass transfer zone profile.
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Wang, Zhi-Da, and 王子達. "The granular activated carbon adsorption isothermal and adsorption bed design application to remove chlorine in hemodialysis Water." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/48253110144617154353.
Full textAbstract:
碩士中原大學
生物醫學工程研究所
99
Abstract Chlorine/chloramine residues in water have a considerable threat to hemodialysis patients. According to relevant literature, chlorine/chloramine residues in water are related to the hemolysis phenomenon during the treatment of dialysis patients. In addition, among all the water treatment procedures of dialysis, only the activated carbon adsorption procedure can effectively eliminate chlorine/chloramine residues in water to reduce the hemolysis phenomenon of dialysis patients. The purpose of this study is to estimate the breakthrough time and filling height of the activated carbon adsorption bed by the mathematical models of the isotherm adsorption and fixed bed adsorption theories, in order to effectively remove the chlorine/chloramine residues in water and reduce the occurrence of hemolysis phenomenon of the dialysis patients during dialysis. This study conducted three types of tests using the clinically used activated carbon adsorbents. The first type test was the adsorption speed test using a fixed amount of activated carbon; the secondary test was the isotherm adsorption test of using different amounts of activated carbon in sodium hypochlorite solution of given volume, and conducted regression analysis and relevant analysis of the adsorption results to find the appropriate isotherm adsorption model; the third type of test was the fixed bed adsorption simulation test with carbon adsorption device of scaled dwon specifications for clinical use, and the adsorption results were analyzed using the fixed bed adsorption mathematical theoretical model. The results suggested that the clinically used activated adsorbents can effectively reduce the chlorine/chloramine residues in water in 5 min, and completely eliminate them in 15 min. The regression analysis of the isotherm adsorption testing results found that the clinically used activated carbon adsorbent can facilitate adsorption with the adsorption index (1/n) at 0.52. A comparison with the relevant analysis results of Langmuir and Freundlich found that the adsorbent can better fit the Freundlich isotherm adsorption model with correlation coefficient at 0.91. The fixed bed adsorption simulation results suggested that the breakthrough time of the column adsorption were 13 hr and the saturated adsorption time was 21 hr. By the mathematical model of the fixed bed adsorption theory, the column adsorption belt (δ) was 0.02 m, and the column adsorption belt moving speed (ν) was 3.04 x 10-3(m/hr), number of moving units (Nf) was 3.61 and the total capacity (Kfav) was 9925.23(1/hr). By inputting different theoretical solution concentrations into the theoretical mathematical model, it was confirmed by calculation that the theoretical adsorption time and testing time of the model have good correlation. The relevant parameters of the clinically used carbon adsorption device were input into the theoretical mathematical model to obtain the theoretical filling bed height (Z) of theoretical scaling up as 0.87 m, which was a gap of 0.13 m from the filling height bed height of 1 m, as provided by the manufacturer. The theoretical breakthrough time was 8760 hr, which was consistent with the manufacturer-suggested replacement time. By isotherm adsorption test and the fixed bed adsorption theoretical mathematical model, the breakthrough time and filling height of the activated carbon filling bed can be estimated to effectively eliminate the chlorine/chloramine residues in water to reduce the occurrence of hemolysis phenomenon of dialysis patients during dialysis.
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Santos, Cristiana Areia dos. "Bioactive compounds separation with simulated moving bed technology." Master's thesis, 2018. http://hdl.handle.net/10773/25696.
Full textAbstract:
Natural products have been progressively forgotten by major pharmaceutical
research companies as sources for new drugs in the last half century.
Currently one observes a change of strategy, which is promoting a renewed
interest on the integration of natural products into pharmaceuticals. Triterpenic
acids are a promising group of plant secondary metabolites occurring
in cuticular waxes covering fruits, owers, and leaves, providing a wide variety
of bene cial biological activities. In this dissertation it was studied the
oleanolic and ursolic acids isolation by chromatographic tecnique of simulated
moving bed (SMB). The seperation of triterpenic acids is complex due
their similar structure. EgiChem laboratory (CICECO, UA) has a SMB unit,
but it is necessary to carry out preliminary experiments in order to select
the best mobile phase and optimal operating conditions for separation of
both acids. For that, it was analyzed the infuence of the solvent/mixture
of solvents on the chromatographic separation by measuring selectivity, retention
factor and resolution. It was tested a triacontyl column (Acclaim
C30), and the best results were obtained with a mobile phase of methanol/
water 95/5 (%, v/v). Then, breakthrough curves have been measured
in order to determine process parameters like the equilibrium isotherms (constants
Hi) of both oleanolic and ursolic acids, and the global linear driving
force (LDF) coe cients of mass transfer (KLDF,i). Data modeling was accomplished
using Klinkenberg equation, which is specifcially applicable to
linear systems. The equilibrium constants of oleanolic and ursolic acdis were
HOA= 2.06 and HUA= 2.16, respectively, and global LDF coe cients were
KLDF,OA= 30.48 min-1 and KLDF,UA= 101.45 min-1 with average deviaions
of AADROA=18.29 % and AADRUA=26.88 %. Finally the simulation of a
SMB unit for a oleanolic/ursolic acids mixture separation was accomplished,
with a 2-2-2-2 con guration, using the packing of Acclaim C30 column and
methanol/water 95/5 (%, v/v) as mobile phase and the equilibrium and
kinetic parameters previously optimized. The obtained results for con guration
showed that the separation of oleanolic and ursolic acids is viable, being
possible to produce puri ed streams of each acid with concentrations above
99%.No último meio século, os produtos naturais tem sido gradualmente esquecidos pelas maiores companhias de investigação farmacêuticas como fontes de novos medicamentos. Porém atualmente observou-se uma mudança de estratégia que promoveu um novo interesse na integração dos produtos naturais nestes. Os ácidos triterpénicos fazem parte de um grupo promissor de metabolitos secundários que podem ser encontrados em plantas, flores, folhas com grande variedade de benficios. Nesta dissertação estudou-se o isolamento dos ácidos oleanólico e ursólico por técnicas cromatográficas, recorrendo à tecnologia de leito móvel simulado (SMB). A separação dos ácidos triterpénicos é complexa dada à sua semelhança estrutural. No laboratório do grupo EgiChem (CICECO, UA) está a ser instalada uma unidade de SMB, porém é necessário realizar ensaios preliminares para selecionar a fase móvel mais adequada, bem como a otimização das condições de operação de ambos os ácidos. Posto isto, analisou-se a influência do solvente/mistura de solventes na separação cromatográfica recorrendo à medição de seletividades, factores de retenção e resolução. Foi testada uma coluna triacontyl (Acclaim C30), sendo que os melhores resultados foram obtidos com a fase móvel metanol/água 95/5 (%, v/v). Seguiu-se à medição das curvas de rutura de modo a determinar os parametros de processo como as isotérmicas de equilibrio (constantes Hi) do ácido oleanólico e do ácido ursólico, e os coeficientes globais de transferência de massa do modelo da força motriz linear (KLDF,i). Os dados obtidos foram modelados através da equação de Klinkenberg, que é aplicado especificamente para sistemas lineares. As constantes de equilíbrio linear dos ácidos oleanólico e ursólico foram HOA= 2.06 e HUA= 2.16, respetivamente, e os coeficientes globais de transferência de massa LDF de KLDF,OA= 30.48 min-1 e KLDF,UA= 101.45 min-1 com desvios médios de AADROA=18.29 % e AADRUA=26.88 %. Por fim foi realizada uma simulação de uma unidade SMB para a separação de uma mistura de ácidos oleanólico e ursólico, com uma configuração 2-2-2-2, usando o enchimento da coluna Acclaim C30 e a fase móvel metanol/água 95/5 (%, v/v) e os parâmetros de equilibrio e cinética otimizados anteriormente. Os resultados obtidos para esta configuração mostraram que é possível produzir correntes purificadas de cada ácido com concentrações acima dos 99%.
Mestrado em Engenharia Química
Books on the topic "BET adsorption isotherms"
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Shields, Joan E., Martin A. Thomas, Matthias Thommes, and S. Lowell. Characterization of Porous Solids and Powders: Surface Area, Pore Size and Density (Particle Technology Series). Springer, 2006.
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1931-, Lowell S., and Lowell S. 1931-, eds. Characterization of porous solids and powders: Surface area, pore size, and density. 4th ed. Boston: Kluwer Academic Publishers, 2004.
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Characterization of Porous Solids and Powders: Surface Area, Pore Size and Density. Springer, 2012.
Find full textBook chapters on the topic "BET adsorption isotherms"
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Cai, Tingting, Dong Zhao, and Zengchao Feng. "Study on coal-bed methane isothermal adsorption at different temperatures based on the monolayer adsorption theory." In Advances in Energy and Environment Research, 176–82. Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742: CRC Press, 2017. http://dx.doi.org/10.1201/9781315212876-36.
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Yu, Wei, and Kamy Sepehrnoori. "Modeling Gas Adsorption in Marcellus Shale Using Langmuir and BET Isotherms." In Shale Gas and Tight Oil Reservoir Simulation, 129–54. Elsevier, 2018. http://dx.doi.org/10.1016/b978-0-12-813868-7.00004-3.
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Taofeek Popoola, Lekan, and Alhaji Shehu Grema. "Adsorption of Heavy Metals from Industrial Wastewater using Nanoparticles from Agro Wastes." In Nanopores [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98241.
Full textAbstract:
Effluents from essential industries have been characterized with heavy metals which are non-biodegradable in nature and also detrimental to health when accumulated in body tissues over long exposure. Adsorption was proved as the best efficient process amongst others to remove these heavy metals from industrial wastewater due to its excellent features. Activated carbons from nanoparticles of agricultural wastes such as pods, shells, husks, peels, shafts and many prepared via calcination process at high temperature can be used as active adsorbent for the industrial wastewater treatment involving heavy metals removal. This chapter discusses heavy metals in industrial wastewater effluents and potential agro wastes from which nanoparticles of activated carbon for industrial wastewater purification could be generated. The transformation of agro wastes nanoparticles into activated carbons via calcination and their applications for heavy metals removal from industrial wastewater via adsorption were examined. Various characterization techniques to study the effects of calcination on structural, morphological and textural properties of activated carbon prepared from agro waste nanoparticles were also discussed. Various isotherm, kinetics, mechanistic and thermodynamics models to investigate the adsorptive nature of the process were presented. Error functions and algorithms for both the linear and non-linear isotherm models regression to affirm their fitness for prediction were presented. Lastly, proposed adsorption mechanisms of heavy metals removal from industrial wastewater using activated carbons from nanoparticles of agro wastes were presented.
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Pishkari, Rojiar, and Achim Kienle. "Fast and Accurate Simulation of Simulated Moving Bed Chromatographic Processes with Linear Adsorption Isotherms." In Computer Aided Chemical Engineering, 487–92. Elsevier, 2020. http://dx.doi.org/10.1016/b978-0-12-823377-1.50082-3.
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Murathatunyaluk, Siripan, Koranut Srichanvichit, Amata Anantpinijwatna, and Prakob Kitchaiya. "Modeling of Non-Isothermal Adsorption Process in a Silica Gel Desiccant Packed Bed." In Computer Aided Chemical Engineering, 49–54. Elsevier, 2018. http://dx.doi.org/10.1016/b978-0-444-64235-6.50011-5.
Full textConference papers on the topic "BET adsorption isotherms"
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Saha, Bidyut Baran, Kandadai Srinivasan, Anutosh Chakraborty, Khairul Habib, Ibrahim Ibrahim El-Sharkawy, and Shigeru Koyama. "Adsorption Characteristics of Maxsorb-III + Methane Systems by Desorption Experiments." In 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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Luna-Flores, Mario, Mariana Gisela Peña-Juarez, Angélica Mara Bello-Ramirez, Javier Telis-Romero, and Guadalupe Luna-Solano. "Moisture sorption isotherms and isosteric heat sorption of habanero pepper (Capsicum chínense) dehydrated powder." In 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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Armandi, Marco, Barbara Bonelli, and Edoardo Garrone. "Synthesis and Characterization of Mesoporous and Microporous Carbons With Potential Applications as Hydrogen Storage Media." In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95740.
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The preparation and physico-chemical characterization of mesoporous and microporous carbons, obtained via a casting procedure, from a SBA-15 silica and a commercial Na-Y zeolite, is reported. XRD spectra showed that ordered carbon replicas occur in all cases. Micro-Raman spectra showed that rather homogeneous powders are obtained, exhibiting the presence of a graphitized carbon phase of small imperfect graphene sheets, typical of sp2 C, along with an amorphous one, notwithstanding the relatively low temperature adopted during the carbonization processes (1173 K). N2 adsorption isotherms at 77 K allowed the determination of BET surface areas and pore volumes: on account of the high porosity and the low specific weight, with respect to zeolites, for example, these carbon materials could be promising media for hydrogen storage. They could be used as such, or after convenient functionalization or metal doping.
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Chakraborty, Anutosh, Syed Muztuza Ali, and How Wei Benjamin Teo. "Study of Waste Heat Driven Adsorption Cooling System Employing Doped MiL-101(Cr) and Water as Adsorbent Adsorbate Pair." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-50741.
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This article presents the dynamic behaviors of two bed adsorption chiller utilizing the composite adsorbent “immobilization of NH2, -NO2, -OH groups to MiL-101(Cr)” as adsorbent and water as adsorbate, which is based on the experimentally confirmed adsorption isotherms and kinetics data. The experimentally measured MOFs + water based isotherms and kinetics data are fitted with adsorption isotherm models and linear driving force kinetics equations. Compared with the experimental data of conventional adsorption chiller based on zeolites/silica gel-water system, we found that the newly working pair provides better cooling capacity and performances in terms of COP and adsorption bed size. From numerical simulation, it is also found that the cooling capacity can be increased up to 20 percent of the parent silica gel-water adsorption chiller and the COP can be improved up to 25% more at optimum conditions.
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Koç, Banu, Gamze Atar, and Nazan Çağlar. "Moisture sorption characteristics of pistachio." In 21st International Drying Symposium. Valencia: Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/ids2018.2018.7826.
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In this study, the moisture adsorption isotherm of pistachio was determined at 25°C and relative humidity (10-90%), using the standard static, gravimetric method. Eleven sorption models were tested to fit the experimental data. A non-linear regression analysis method was used to evaluate the constants of the sorption equations. The GAB equation gave the best fit to the experimental data for a wide range of water activity, while BET gave the best fit for a water activity range of 0.1-0.5. The agreement between experimental and predicted values of these models was found to be satisfactory. Keywords: Moisture adsorption isotherm; Sorption model; Pistachio
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Alsaba, Wisam Hussam, Raafat Alenany, and Mohammed Zamzam. "Using Synthetic Resins for Removal of Emulsified Oil from Produced Water." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0103.
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In this study, adsorption of emulsified oil in produced water was experimented using synthetic resins. Adsorbent dosage, contact time, initial oil concentration, and PH were the main key parameters evaluated for Optipore L493, Amberlite IRA 958, Amberlite XAD 7 and Lewatit AF 5. Oil removal rates have reached up to 98% using AF 5, XAD 7 and L493, while they are lesser than 25% for IRA 958. Isotherm data were fitted using Langmuir, Freundlich, Toth, Flory Huggins and Dubinin-Radushkevich models. Adsorption isotherms for XAD 7 and L 493 were best fitted using Langmuir model, whereas AF 5 curves were best fitted using Dubinin-Radushkevich. Kinetic data describing the rate of adsorption for each resin were studied and fitted using pseudo-first and second order equations in addition to intraparticle diffusion models. The experimental results were best-fitted using pseudo second order kinetics. The obtained results confirm the applicability of the resins for the removal of oil from produced water.
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Jiabi, Deng, Li Ling, and Yuan Decheng. "Determination of adsorption isotherm of column of simulated moving bed." In 2017 36th Chinese Control Conference (CCC). IEEE, 2017. http://dx.doi.org/10.23919/chicc.2017.8027785.
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ZHAO, Xiaodan, Donghui CHEN, and Yurong ZHANG. "A General Isotherm Model for Activated Carbon Adsorption of Typical Natural Organic Matters." In International Conference on Biological Engineering and Pharmacy 2016 (BEP 2016). Paris, France: Atlantis Press, 2017. http://dx.doi.org/10.2991/bep-16.2017.58.
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Yang, Yun, and Shimin Liu. "Quantification of Temperature-Dependent Sorption Kinetics in Shale Gas Reservoirs: Experiment and Theory." In 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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Hamed, Ahmed M., Walaa R. Abd El Ramadan, and S. H. El-Eman. "Study on the Performance of a Fluidized Air Dehumidifier." In ASME 2005 International Solar Energy Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/isec2005-76202.
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Transient adsorption/desorption characteristics of solid desiccant particles in fluidized bed have been presented. The system operates in batch mode and the atmospheric air with controlled inlet humidity and temperature is dehumidified by the applied desiccant. Also, heated air is used for regeneration purposes. A simplified analytical solution, with isothermal adsorption assumption, is demonstrated. In the experimental study, spherical particles of silica gel about 3 mm in diameter are used as the working desiccant in the fluidized bed. The experimental system is equipped with the necessary control valves to facilitate operation in adsorption and desorption modes, respectively. To control the humidity of inlet air, a humidifier is designed and fitted in a proper location in the system. Also, the system is well instrumented to measure the inlet and outlet air parameters as well as bed temperatures during the operation modes. Transient values of the mass of adsorbed water in the bed, rate of adsorption and water content in silica gel particles are evaluated from the experimental measurements. Also, numerical values of the volumetric mass transfer coefficient are plotted and discussed for different operating conditions. Model output, which shows the dependence of the dimensionless value of water content in the bed [(w*i − w)/(w*i − wo)] on the dimensionless time, is compared with the experimental results. Good agreement is found at the first period of adsorption, when the adsorption is nearly isothermal. Successive increase in bed temperature, due to the heat of adsorption, results in increase in discrepancy between the model and the experimental data. Accordingly, the isothermal model could be applied with reasonable degree of reality for systems with shorter adsorption/desorption cycles. The effect of air inlet humidity on the system operation has been highlighted. The drop in air humidity is highly affected by its inlet value. It is found that, the maximum decrease in air humidity occurs at the beginning of adsorption for the different inlet values. Also, the rate of water vapor adsorption increases with the increase in the inlet humidity.