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Publisher: Springer-Verlag (Total: 2350 journals)

 Adsorption   [SJR: 0.774]   [H-I: 52]   [4 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1572-8757 - ISSN (Online) 0929-5607    Published by Springer-Verlag  [2350 journals]
• On the use of the IAST method for gas separation studies in porous
materials with gate-opening behavior
• Authors: Guillaume Fraux; Anne Boutin; Alain H. Fuchs; François-Xavier Coudert
Pages: 233 - 241
Abstract: Highly flexible nanoporous materials, exhibiting for instance gate opening or breathing behavior, are often presented as candidates for separation processes due to their supposed high adsorption selectivity. But this view, based on “classical” considerations of rigid materials and the use of the Ideal Adsorbed Solution Theory (IAST), does not necessarily hold in the presence of framework deformations. Here, we revisit some results from the published literature and show how proper inclusion of framework flexibility in the osmotic thermodynamic ensemble drastically changes the conclusions, in contrast to what intuition and standard IAST would yield. In all cases, the IAST method does not reproduce the gate-opening behavior in the adsorption of mixtures, and may overestimates the selectivity by up to two orders of magnitude.
PubDate: 2018-04-01
DOI: 10.1007/s10450-018-9942-5
Issue No: Vol. 24, No. 3 (2018)

• Assessing the potential of nanoporous carbon adsorbents from polyethylene
terephthalate (PET) to separate CO 2 from flue gas
• Authors: P. A. S. Moura; E. Vilarrasa-Garcia; D. A. S. Maia; M. Bastos-Neto; C. O. Ania; J. B. Parra; D. C. S. Azevedo
Pages: 279 - 291
Abstract: A series of nanoporous carbons was obtained by physical activation of polyethylene terephthalate and investigated for the separation of CO2 from flue gas. The prepared carbons exhibited extremely low functionalization—negligible content in oxygen and other heteroatoms—accompanied by well-developed porous networks consisting of gradually increasing surface areas and micropore volumes. Such features allowed to study the role of nanopore confinement in the separation of carbon dioxide in CO2/N2 gas mixtures. The analysis of the adsorption isotherms of individual gases and their mixtures revealed different trends for the CO2 uptake and the selectivity. Whereas CO2 uptake was larger in the carbons with higher burn-off degree, the selectivity of CO2 over N2 was favored in the carbons with a higher fraction of narrow micropores. The differential adsorption enthalpy curves are typical of highly microporous samples reaching values close to those found in zeolites for low loadings. Data also show that the choice of the best adsorbent for cyclic gas adsorption and separation processes should consider a broad context, taking into account various parameters simultaneously such as gas selectivity, working capacity, adsorption enthalpy and energy consumption in the synthesis of the adsorbent.
PubDate: 2018-04-01
DOI: 10.1007/s10450-018-9943-4
Issue No: Vol. 24, No. 3 (2018)

• Expanded bed adsorption of albumin and immunoglobulin G from human serum
onto a cation exchanger mixed mode adsorbent
• Authors: Pedro Ferreira Gomes; José Miguel Loureiro; Alírio E. Rodrigues
Pages: 293 - 307
Abstract: Adsorption of human serum albumin (HSA) and immunoglobulin G (IgG), two most relevant proteins in blood serum were measured separately on a new mixed-mode adsorbent (MabDirect MM), especially designed for expanded bed adsorption process. Expanded bed behavior characterization by residence time distribution experiments for different columns (Streamline 50 for HSA study, Omnifit 66/20 and XK 16/20 for IgG study) are presented together with breakthrough adsorption of HSA and IgG for different conditions and compared with simulation results by a mathematical model. Regarding HSA adsorption, all four experiments were conducted at the same buffer solution (pH 5.0 without salt), and it was obtained a dynamic binding capacity of 8.9, 9.7, 7.5 and 7.0 mg·gdry−1 (24.8, 27.0, 21.0 and 19.5 mg·cm−3) at 10% of breakthrough, corresponding to a 41, 39, 38 and 30% of the saturation capacity for runs 1–4, respectively. The results from the simulation of the mathematical model fitted well with the breakthrough experiments. Elution stage was optimized by lowering flow rate and changing the buffer solution pH and NaCl concentration. Concerning IgG adsorption, for IgG feed concentration of 0.53 g·dm−3 in 20 mM citrate buffer, pH 5.0 with 0.4 M NaCl, at 2.2 cm3·min−1, it was obtained a DBC of 3.3 mg·gdry−1 (9.1 mg·cm−3) at 10% of breakthrough, representing 22% of the saturation capacity. While for a feed concentration of 0.11 g·dm−3 of IgG in the same buffer solution, at 6 cm3·min−1, it was obtained a DBC of 2.7 mg·gdry−1 (7.4 mg·cm−3) at 10% of breakthrough, representing 34% of the saturation capacity.
PubDate: 2018-04-01
DOI: 10.1007/s10450-018-9940-7
Issue No: Vol. 24, No. 3 (2018)

• Transesterification of propylene glycol methyl ether by reactive simulated
moving bed chromatography using homogeneous catalyst
• Authors: Jungmin Oh; Balamurali Sreedhar; Megan E. Donaldson; Timothy C. Frank; Alfred K. Schultz; Andreas S. Bommarius; Yoshiaki Kawajiri
Pages: 309 - 324
Abstract: A reactive chromatography process was investigated for a transesterification reaction of propylene glycol methyl ether (DOWANOL™ PM) using a homogeneous catalyst, a sodium alkoxide. In the proposed process, fresh catalyst is supplied with desorbent, which allows independent optimization of the adsorption properties of the stationary phase. Deactivation of catalytic activity can be avoided, which had been found to be the bottleneck in our previous study for heterogeneous catalysis. To model and optimize this process, a series of batch reaction experiments, and pulse injection tests with a chromatographic column with and without reaction were carried out. From the experimental data, equilibrium and kinetic parameters were estimated using the inverse method. Using this model, a simulated moving bed reactor was designed that achieves a conversion of 95% using the homogeneous catalysis concept.
PubDate: 2018-04-01
DOI: 10.1007/s10450-018-9941-6
Issue No: Vol. 24, No. 3 (2018)

• Axial dispersion effects with small diameter adsorbent particles
• Authors: Aaron Moran; Mihir Patel; Orhan Talu
Pages: 333 - 344
Abstract: Macropore diffusion is traditionally assumed to control the mass transfer rate in columns packed with zeolite particles in an oxygen production process. While numerous studies have confirmed this assumption for the particle size used in industrial size pressure swing adsorption (PSA) processes, it has not been validated for the much smaller particle size used in rapid PSA (RPSA). Smaller particles improve the mass transfer rate by increasing interfacial area per volume as well as decreasing diffusion distance. Despite this reduction, RPSA simulations often still assume a mass transfer rate solely limited by macropore diffusion. This approach fails to adequately account for the influence of other mass transfer mechanisms whose impact increases due to particle size reduction. This study experimentally demonstrates the dominant mass transfer mechanism is no longer macropore diffusion for the particle size used in RPSA for small scale oxygen production. Depending on the gas velocity, axial dispersion effects either become the limiting mechanism or equally as important as macropore diffusion. It also shows that improperly accounting for axial dispersion effects has a significant impact on the mass transfer coefficient estimation, often measured with breakthrough experiments.
PubDate: 2018-04-01
DOI: 10.1007/s10450-018-9944-3
Issue No: Vol. 24, No. 3 (2018)

• Armin Bunde, Jǖrgen Caro, Jȍrg Kȁrger and Gero Vogl (eds): Diffusive
spreading in nature, technology and society
• Authors: Douglas Ruthven
PubDate: 2018-04-26
DOI: 10.1007/s10450-018-9950-5

• Microstructure effect of carbon materials on the low-concentration methane
adsorption separation from its mixture with nitrogen
• Authors: Donglei Qu; Ying Yang; Kai Lu; Lin Yang; Ping Li; Jianguo Yu; Ana Mafalda Ribeiro; Alirio E. Rodrigues
PubDate: 2018-04-23
DOI: 10.1007/s10450-018-9951-4

• Theoretical insights into the mechanism of CO 2 physisorption on Al–N
ring doped on the carbon nanotube: a DFT study
• Authors: A. S. Ghasemi; F. Ashrafi; H. Pezeshki; M. Molla; M. Rokni
Abstract: Carbon nanotubes are the most important nanotechnology combinations, one of their most important applications being in the science of nano-electronic segments. In the present study, CO2 molecule interaction with the outer surface of Zigzag (5,0) and Armchair (5,5) carbon nanotubes with specified and optimized lengths and diameters has investigated. Significance of this study is injection of insoluble carbon dioxide gas expanded in the reservoir, causing fluid movement towards the wellhead. Therefore, theoretical approaches have used to investigate the adsorption of CO2 on single-wall carbon nanotubes, identify the adsorption structure and the attached carbon-to-gas configuration, and to calculate the parameters such as energy gap in carbon-gas nanotube structures that can help to identify carbon-gas nanotube complex stability. Results revealed that CO2 molecule reaction with nanotube surface generates diverse adsorption structures. The best CO2 gas adsorption has obtained on the surface of carbon nanotubes (5,5) doped with the Al–Nitride ring.
PubDate: 2018-04-21
DOI: 10.1007/s10450-018-9949-y

• Effect of adsorbent heterogeneity on performance of a PSA process for bulk
gas separation: a parametric simulation
• Authors: Rama Rao Vemula; Shivaji Sircar
PubDate: 2018-03-31
DOI: 10.1007/s10450-018-9947-0

• Confinement effect on enthalpy of fusion and melting point of organic
phase change materials in cylindrical nanospace of mesoporous silica and
carbon
• Authors: Jihye Choi; Hirotaka Fujita; Masaru Ogura; Akiyoshi Sakoda
Abstract: Organic phase change materials (PCMs) were successfully confined into mesopores of host materials independently via vapor transportation to precisely investigate the changes in the enthalpy of fusion and the melting point of such confined PCMs under various conditions. Paraffins, fatty acids, and fatty alcohols with long hydrocarbon chains were employed as guest PCMs. Mesoporous silica SBA-15s and soft-templated mesoporous carbons with cylindrical mesopores were employed as host materials of the guest PCMs. It was elucidated that mesopore diameter, functional groups of both PCMs and functional groups of host materials result in significant changes in the enthalpy of fusion and the melting point of confined PCMs. Furthermore, it was concluded that the host materials with mesopores of diameter 10–20 nm and minimum interaction between PCM molecules and the functional group on the wall of mesopores of host materials are required to obtain an enthalpy of fusion of confined PCMs as much as 50% of that in its bulk phase.
PubDate: 2018-03-26
DOI: 10.1007/s10450-018-9946-1

• Enhanced $$\text {CO}_2$$ CO 2 selectivity within the cavity of gmelinite
frameworks
• Authors: Anastasios Gotzias; Michael Kainourgiakis; Athanassios Stubos
Abstract: We simulate the adsorption of $$\text {CO}_2$$ mixtures in three zeolitic imidazolate frameworks, namely ZIF70, ZIF80 and ZIF82. The structures display a dual pore composition with a network topology that resembles the cavity of the gmelinite zeolite. We compute the adsorption density in the pore partitions of the cavities by allocating the particle distributions of the mixture components at the individual regions of the pore network. We detect that the $$\text {CO}_2$$ adsorption and the selectivity performance, are enhanced in one group of pore channels. For ternary mixtures adsorption simulations, within the hexahedral pore channels of ZIF82, we evaluate $$\simeq 14$$ for $$\text {CO}_2$$ / $$\text {CH}_4$$ and $$\simeq 34$$ for $$\text {CO}_2$$ / $$\text {N}_2$$ selectivity at 1 bar and 298 K, which are among the highest reported selectivity values at such conditions, for the class of porous frameworks, including the metal organic frameworks (MOFs).
PubDate: 2018-03-15
DOI: 10.1007/s10450-018-9945-2

• Analysis of ideal sorption compressor cycles operating with gas mixtures
• Authors: N. Tzabar; H. J. M. ter Brake
Abstract: Sorption-based compressors are thermally driven and because of the absence of moving parts they are vibration free, and have the potential for long life. Sorption-based compressors have been reported to operate Joule–Thomson (JT) cryogenic coolers with pure working fluids. However, using mixed refrigerants instead of pure refrigerants is attractive since that would dramatically improve the system coefficient of performance. Our on-going research aims to develop an efficient JT sorption cryocooler, operating with mixed refrigerants, and is focused on studying the characteristics of the sorption compressor cycle. This paper presents the results of an advanced numerical analysis, which is based on a previous model, and its experimental verification. The analysis relates to the ideal cycle of a sorption compressor operating with a gas mixture. Obviously, dynamics and kinetics play a major rule in a real sorption compressor cycle. However, since there are no reported gas-mixture sorption compressors and the existing experience in this field is poor, a preliminary ideal cycle analysis is considered. Satisfying agreement between the numerical and experimental results is obtained and the processes in the sorption cycle are discussed. The outcomes of the current study are the basis for the next phase in which a sorption compressor prototype will be built operating with gas mixtures.
PubDate: 2018-02-26
DOI: 10.1007/s10450-018-9937-2

• Chloride adsorption on Fe- and Al-(hydr)oxide: estimation of Gibbs free
energies
• Authors: N. Y. Acelas; E. Flórez
Abstract: In this study, we used chemical quantum methods to analysis the adsorption of chloride on Al and Fe-(hydr)oxide clusters. Inner and outer sphere complexes were the generating complexes during the adsorption process on variably charged Al- and Fe-(hydr)oxide clusters. For the chloride adsorption on Al-(hydr)oxide, the outer sphere complexes—H-bonded—were favored for all clusters, while the adsorption modes as inner sphere complexes—BB or MM—were not favored. It was found, that the H-bonded complex on neutral clusters was the most thermodynamically favored with an adsorption energy of − 63.4 kJ/mol. For iron clusters, thermodynamic favorability was observed for both outer (− 70.5 kJ/mol) and inner monodentate (− 65.8 kJ/mol) sphere complexes. These theoretical results indicated that the thermodynamic favorability of chloride adsorption on Fe and Al-(hydr)oxide was directly related to positive surface charge.
PubDate: 2018-02-21
DOI: 10.1007/s10450-018-9939-0

• New hybrid composite honeycomb monolith with 13X zeolite and activated
carbon for CO 2 capture
• Authors: Maria João Regufe; Alexandre F. P. Ferreira; José Miguel Loureiro; Yixiang Shi; Alírio Rodrigues; Ana Mafalda Ribeiro
Abstract: Due to the industrialization, it is urgent to reduce the carbon dioxide emissions. For that, diverse technologies can be applied. In adsorption processes, the development of new materials is an emerging challenge in order to increase the CO2 adsorption capacity of materials and the efficiency of the processes. In this work, a new hybrid honeycomb monolith composed by zeolite and activated carbon was produced by extrusion process. Single adsorption equilibrium isotherms of carbon dioxide and nitrogen were measured by a gravimetric method using a Rubotherm® magnetic suspension balance at three temperatures, 303, 333 and 373 K. The experimental points were well described by Dual-Site Langmuir model. The material presented a carbon dioxide adsorption capacity of 2.63 mol kg−1 at 1 bar and 303 K. Binary breakthrough curves were obtained at 298 K and 2.4 bar with different feed mixtures. The experimental results of adsorption equilibrium were validated with the Dual-Site Langmuir isotherm extended to multicomponent mixtures. A mathematical model was applied to predict the dynamic behaviour of the adsorption bed.
PubDate: 2018-02-17
DOI: 10.1007/s10450-018-9938-1

• Characterization of hydroxylated amorphous silica: a numerical approach
• Authors: Nicholas W. Suek; Maxime C. Guillaume; Jean-Yves P. Delannoy; Frederik Tielens
Abstract: Hydroxylated amorphous silica nanoparticles were modeled using a combination of computational techniques at different levels of length scales from Ångström to hundreds of nanometers. Using quantum chemical ab initio methods, force field Monte Carlo methods, reactive force field simulations, and numerical model calculations, including BET theory calculations it was possible to describe and model the physico-chemical properties of hydroxylated amorphous silica. The results are compared with experimental data and found to be in good agreement with the theory, confirming the reliability of the computational method and the silica model structure.
PubDate: 2018-02-12
DOI: 10.1007/s10450-018-9936-3

• Resorcinol–formaldehyde carbon xerogel as selective adsorbent of carbon
dioxide present on biogas
• Authors: Jose F. Vivo-Vilches; Agustín F. Pérez-Cadenas; Francisco J. Maldonado-Hódar; Francisco Carrasco-Marín; Maria J. Regufe; Ana M. Ribeiro; Alexandre F. P. Ferreira; Alirio E. Rodrigues
PubDate: 2018-01-23
DOI: 10.1007/s10450-018-9933-6

• Graphical approach for formulating pressure swing adsorption cycle
schedules with unlimited equalization steps
• Authors: Armin D. Ebner; Jason G. S. Ho; James A. Ritter
Abstract: A graphical unit block was used to formulate new PSA cycle schedules that include an unlimited number of equalization steps, no idle steps, no dead time and a minimum number of just three PSA beds assisted with two or more equalization tanks. The approach to designing these PSA cycle schedules is based on three simple rules: (1) restrict the placement of all the equalization steps within the boxes of the PSA cycle schedule to be in sequence with no other cycle steps in between them; (2) place all the equalization steps in the left most boxes of the PSA cycle schedule underneath the Bed 1 feed step with no other cycle steps below them except other equalization steps; and (3) add equalization tanks as needed. These new 3-bed PSA cycle schedules may include any of the common PSA cycle steps in such a way that the equalization steps do not interfere with any of the non-equalization steps affording the non-equalization steps additional degrees of freedom. Since a bed-to-tank-to-bed equalization step may not be as effective as a bed-to-bed equalization step, a forced cocurrent depressurization (CoD) step coupled with an intermediary light end pressurization (LEP) step can be added to this 3-bed PSA cycle schedule. These coupled steps take place after the last of the equalization down and up steps with the aid of a compressor or vacuum pump. Since the utilization of several equalization steps and the utilization of forced CoD/LEP steps may limit the duration of the countercurrent depressurization (CnD) and/or light reflux (LR) steps, one or more additional beds can also be added to this 3-bed PSA cycle schedule. These additional beds increase the durations of the CnD and LR steps without affecting the duration of the feed step. Any combination of these PSA cycle schedule improvements can be used to improve the PSA process performance in terms of capital and operating costs, productivity or throughput, and recovery and purity of the species of interest whether it is the heavier, lighter or both species.
PubDate: 2018-01-18
DOI: 10.1007/s10450-018-9934-5

• DFT study of the adsorption and dissociation of
5-hydroxy-3-butanedithiol-1,4-naphthaquinone (Jug-C4-thiol) on Au(111)
surface
• Authors: Karima Lassoued; Mahamadou Seydou; Fayçal Raouafi; Fadhel Larbi; Philippe Lang; Boubakar Diawara
Abstract: Density functional theory has been used to investigate the adsorption and dissociation of 5-hydroxy-3-hexanediol-1,4-naphthaquinone (Jug-C4-thiol) at a coverage of p(4 × 4) on a Au(111) surface. Both physisorption and chemisorption processes are investigated. For each process, the surface energy potential is explored by an exhaustive test of the adsorption site. The most favorable site is found to be face-centered cubic. The adsorption energies are less than − 0.20 eV in the case of physisorption, while they range from − 1.70 to − 1.92 eV for chemisorption. The effect of the naphthoquinone function is negligible in the adsorption process. The alkyl chain inhibits electron delocalization between the surface and the conjugated head of the molecule. Analysis of the bonding shows the formation of two ionocovalent bonds between the sulfur and the gold atoms. The thermodynamics and kinetics of S–H bond dissociation are studied. The results reveal that adsorption involves a dissociation path in which a hydrogen atom moves to the most neighboring site and a hydrogen atom migrates to its most stable site. The maximum barrier energy of the first step is less than 2.7 eV while the migration barrier does not exceed 0.5 eV.
PubDate: 2018-01-17
DOI: 10.1007/s10450-018-9932-7

• Towards polymer grade ethylene production with Cu-BTC: gas-phase SMB
versus PSA
• Authors: Vanessa F. D. Martins; Ana M. Ribeiro; Jong-San Chang; José M. Loureiro; Alexandre Ferreira; Alírio E. Rodrigues
Abstract: The recovery of ethylene as a product from ethylene/ethane mixtures by adsorptive processes has been attracting great interest due to the high operating and capital costs of the cryogenic distillation traditionally practiced. This search for novel economical ways to separate olefins from paraffins by adsorptive processes has motivated the appearance of improved materials. The trend of developing new materials, such as metal–organic frameworks (MOF) and the challenge of improving the existing technologies, such as pressure swing adsorption (PSA) and simulated moving bed (SMB) leave the horizon open for new alternatives. In the present work, PSA and SMB in gas phase were tested to produce ethylene at high purity on Cu-BTC MOF in beads form. For the first time, the olefin/paraffin separation by SMB technology, using a MOF as adsorbent, was achieved. Both technologies were successfully implemented experimentally and simulated. In the best cycle performed by VPSA for the 20/80 ethane/ethylene feed composition, the ethylene was obtained with a purity of 98.0% at a recovery of 70.2% and a productivity per unit mass of stationary phase of 1.55 molC2 h−1 kg−1adsorbent. Additionally, for the 50/50 ethane/ethylene mixture only 43.2% of the ethylene is recovered at a purity of 95.4% and a productivity of 0.52 molC2 h−1 kg−1adsorbent. In the two cycles performed by SMB, to separate 39/61 ethane/ethylene mixture, ethylene was obtained with a purity of 95%, a recovery above 90% and productivity between 0.50 and 0.66 molC2 h−1 kg−1adsorbent. All the experiments were well predicted by the axial dispersion flow model with the LDF approximation.
PubDate: 2018-01-05
DOI: 10.1007/s10450-017-9930-1

• Chromium(VI) removal using in-situ nitrogenized activated carbon prepared
from Brewers’ spent grain
• Authors: S. R. H. Vanderheyden; K. Vanreppelen; J. Yperman; R. Carleer; S. Schreurs
Abstract: In-situ nitrogenised activated carbons (ACs) are prepared from brewers’ spent grain (BSG) using different activation procedures. Cr(VI) adsorption (10 mg/L, pH 2) on these ACs is compared to adsorption on commercial Norit GAC 1240 and Filtrasorb F400. The adsorption isotherms for both Cr(VI) and Cr total (Crtot) are determined for each AC, of which the best performing ones are chosen for kinetic experiments. The adsorption mechanism towards Cr(VI) is accompanied by its reduction to Cr(III), removing almost all Cr(VI) even at low dosages for all tested ACs. An optimal dosage (0.75 g/L) is found for each AC. For the best performing AC this dosage results in removal rates of over 99% of Cr(VI) and 88% of Crtot. The amount of reduced Cr(VI) increases with AC dosage, resulting in a higher Cr(III) equilibrium concentration above this optimal dosage. The redox reaction is more dominant in the commercial ACs. However, a faster removal rate for the ACBSGs for both Cr(VI) and Crtot is demonstrated.
PubDate: 2017-12-13
DOI: 10.1007/s10450-017-9929-7

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