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 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  [2329 journals]
• Oxygen uptake, selectivity and reversibility of Tb–CeO 2 mixed
oxides for air separation
• Authors: Anita M. D’Angelo; Alan L. Chaffee
Pages: 465 - 475
Abstract: A series of Tb–CeO2 mixed oxides were investigated as novel oxygen sorbents. The relationship between %Tb content-oxygen uptake, alongside the selectivity and reversibility of these materials, was determined via chemisorption (400, 500 and 600 °C) and supporting thermogravimetric studies at 500 and 600 °C. Oxygen chemisorption experiments conducted at 600 °C showed higher uptakes were achieved by incorporating more Tb into the CeO2 crystal lattice. The uptake of 40 mol% Tb–CeO2 was 121 μmol g−1 and for 10 mol% Tb–CeO2 the uptake was 34 μmol g−1. Increasing the analysis temperature for each material resulted in an increase in uptake as more oxygen was able to be removed. All materials exhibited good reversibility and cyclic stability during alternating N2 and air atmospheres at 600 °C. High O2/N2 selectivity was also demonstrated as no detectible uptake was observed at 600 °C using N2 as the adsorbate. The data suggests that these materials may have applications in air trace gas removal or as membranes for air separation applications.
PubDate: 2017-05-01
DOI: 10.1007/s10450-016-9855-0
Issue No: Vol. 23, No. 4 (2017)

• Optimising batch adsorbers for the removal of zinc from effluents using a
sodium diimidoacetate ion exchange resin
• Authors: Alireza Bazargan; Tsz-Him Shek; Chi-Wai Hui; Gordon McKay
Pages: 477 - 489
Abstract: An ion exchange resin, based on the sodium diimidoacetate structure, has been tested for the removal of zinc ions from effluents. After employing three isotherm models, namely, Langmuir, Freundlich and Langmuir–Freundlich to measure and analyse equilibrium isotherms, a series of agitated batch experiments have been carried out to optimise the removal of zinc ions in a two-stage batch system. The first optimisation model involves minimising the total amount of resin required to achieve a specific percentage zinc removal. The second optimisation study involves minimising the total batch contact time to achieve a certain percentage zinc removal.
PubDate: 2017-05-01
DOI: 10.1007/s10450-016-9857-y
Issue No: Vol. 23, No. 4 (2017)

equilibrium and kinetics
• Authors: Pedro Ferreira Gomes; José Miguel Loureiro; Alírio E. Rodrigues
Pages: 491 - 505
PubDate: 2017-05-01
DOI: 10.1007/s10450-017-9861-x
Issue No: Vol. 23, No. 4 (2017)

• Adsorption of propylene, propane, ethylene and ethane in an isoreticular
series of MOF-74 structures
• Authors: Mohammad Gholami; Saeid Yeganegi
Pages: 507 - 514
PubDate: 2017-05-01
DOI: 10.1007/s10450-017-9862-9
Issue No: Vol. 23, No. 4 (2017)

• Multi-cell model for pressure swing adsorption process
• Authors: Satyanjay Sahoo; Anshu Shukla; Arun S. Moharir
Pages: 515 - 534
Abstract: Pressure Swing Adsorption process is a discrete–continuous system by nature and it is extremely time consuming to simulate steady state performance for a given set of design and operating parameters. A multitude of design variations is offered by the configuration of Pressure Swing Adsorption cycle in terms of choice, sequence, and durations of various possible component steps implemented on two or more adsorber beds. Often, simplifying assumptions are made to speed up each simulation. These assumptions erode the quality of match between reality and simulation and make the resultant design approximate. Use of assumptions like no adsorption/desorption during the pressurization and blowdown steps, constancy in volumetric flow during the adsorption and purge steps makes the model computationally lighter but raises questions on its predictive power. A new modeling approach, namely Multi-cell Model is presented in this work. It is shown to avoid the extensive time taken with equation-based simulations and to have better predictive power. The model is used to study a representative Pressure Swing Adsorption process for nitrogen enrichment from the air. Numerical convergence with respect to the spatial and temporal step sizes and mass balance closure is verified. The model is generic in nature and is valid for any multi-bed, multi-adsorbent, multi-component Pressure Swing Adsorption process executing any combination of component steps.
PubDate: 2017-05-01
DOI: 10.1007/s10450-017-9865-6
Issue No: Vol. 23, No. 4 (2017)

• The design and operation of a simulated moving bed for the separation of
intermediate retention components from a multi-component feedstock with a
very strong retention component
• Authors: Ru-Chien Liang; XiaoQing Bao; Ly Sung; Chih-Hsiung Lin; Ming-Tsai Liang
Pages: 535 - 549
Abstract: This study presents two designs for a seven-zone SMB (Simulated Moving Bed) and the procedures for establishing the operating conditions for the direct separation of IRC (intermediate retention component) from a feedstock with VSRC (very strong retention component). Normally, the crude extract from natural products or fermented liquid can rarely be directly applied as the feedstock for continuous chromatography due to its multiple components and VSRC. Two SMBs connected in series can usually work to separate a ternary mixture; yet, an additional zone for CIP (cleaning in place) is commonly required to remove the VSRC. By using a seven-zone SMB, this study successfully separates the IRC from two different crude extracts with VSRC. By examining the relative retention of IRC to WRC (weak retention components), this study proposes two SMB designs to separate the IRC. Based on the Triangle theory, a three-step procedure is also proposed, and two crude extracts: an anticancer drug produced by fermentation and astaxanthin extracted from red algae, were used as working examples in this study. Both samples showed that the separation of the IRC with near 90% purity and recovery can be achieved by following the three-step procedure without knowing the adsorption isotherms of the impurities, which will quickly provide useful information for further feasibility studies and scaled-up designs.
PubDate: 2017-05-01
DOI: 10.1007/s10450-017-9866-5
Issue No: Vol. 23, No. 4 (2017)

• An analysis of the effect of the additional activation process on the
formation of the porous structure and pore size distribution of the
commercial activated carbon WG-12
• Authors: Mirosław Kwiatkowski; Joanna Sreńscek-Nazzal; Beata Michalkiewicz
Pages: 551 - 561
Abstract: The paper presents the results of research into the effects of the additional activation process of the commercial activated carbon WG-12 with KOH, ZnCl2, KOH/ZnCl2 and K2CO3 as activating agents on the formation of the porous structure and the adsorptive properties of that material. The numerical analyses were carried out on the basis of the isotherms of nitrogen adsorption with the use of the method based on the Brunauer-Emmett-Teller, the Dubinin-Radushkevich equations, the non-local and the quenched solid density functional theories as well as the LBET method with the unique fast multivariate procedure of porous structure identification and the new LBET class adsorption models. Also, the research in question yielded information regarding the usefulness of the said methods of carbonaceous adsorbent porous structure description for practical technological applications and scientific research, as well as the possibilities to make practical use of the research results.
PubDate: 2017-05-01
DOI: 10.1007/s10450-017-9867-4
Issue No: Vol. 23, No. 4 (2017)

• Monosaccharide separation from ZnCl 2 molten salt hydrates by zeolite beta
• Authors: Johan van den Bergh; Wouter Wiedenhof; Dorota Siwy; Hans Heinerman
Pages: 563 - 568
Abstract: Solvent based processes using ionic liquids or molten salt hydrates provide very efficient cellulose dissolution and hydrolysis from lignocellulosic biomass. Efficient separation of sugars from the solvent is very challenging and a hurdle regarding industrial application. Now it is demonstrated that a microporous zeolitic sorbent can provide a very efficient separation of monosugars from a molten salt hydrate containing hydrolysates. Specific details are presented for the separation of glucose from a ZnCl2 molten salt hydrate using Zeolite beta. The molten salt hydrate is promoting the separation in this specific solvent/sorbent combination through a type of salting out adsorption mechanism, leading to a process based on a solvent that allows both efficient cellulose dissolution and hydrolysis and very efficient glucose isolation from the solvent afterwards.
PubDate: 2017-05-01
DOI: 10.1007/s10450-017-9868-3
Issue No: Vol. 23, No. 4 (2017)

• Authors: Stefano Brandani; Enzo Mangano; Mauro Luberti
Pages: 569 - 576
Abstract: The formulation of a thermodynamic framework for mixtures based on absolute, excess or net adsorption is discussed and the qualitative dependence with pressure and fugacity is used to highlight a practical issue that arises when extending the formulations to mixtures and to the Ideal Adsorbed Solution Theory (IAST). Two important conclusions are derived: the correct fundamental thermodynamic variable is the absolute adsorbed amount; there is only one possible definition of the ideal adsorbed solution and whichever starting point is used the same final IAST equations are obtained, contrary to what has been reported in the literature.
PubDate: 2017-05-01
DOI: 10.1007/s10450-017-9875-4
Issue No: Vol. 23, No. 4 (2017)

• Comparing multi-column chromatographic processes for purifying
monosaccharides part I: A simplified approach
• Authors: Laurent David; Jay Yun; Roger-Marc Nicoud
Pages: 577 - 591
Abstract: This work proposes a methodology for comparing different multi-column chromatographic processes (SMB, ISMB, SSMB) for purifying monosaccharides. The first step of the methodology consists in determining the flow rates associated with the different processes assuming that the columns are infinitely efficient. This allows deriving “idealized” operating conditions. In a second step, using the “idealized” conditions, the behavior of the real systems associated with columns of finite efficiencies are simulated with ChromWorks™ and compared. It is shown that the SMB performs better than single column elution chromatography, and that, for the application selected, ISMB and SSMB are very similar and perform better than SMB.
PubDate: 2017-05-01
DOI: 10.1007/s10450-017-9878-1
Issue No: Vol. 23, No. 4 (2017)

• Relationship between pore-size distribution and flexibility of adsorbent
materials: statistical mechanics and future material characterization
techniques
• Authors: Daniel. W. Siderius; Nathan. A. Mahynski; Vincent K. Shen
Pages: 593 - 602
Abstract: Measurement of the pore-size distribution (PSD) via gas adsorption and the so-called “kernel method” is a widely used characterization technique for rigid adsorbents. Yet, standard techniques and analytical equipment are not appropriate to characterize the emerging class of flexible adsorbents that deform in response to the stress imparted by an adsorbate gas, as the PSD is a characteristic of the material that varies with the gas pressure and any other external stresses. Here, we derive the PSD for a flexible adsorbent using statistical mechanics in the osmotic ensemble to draw analogy to the kernel method for rigid materials. The resultant PSD is a function of the ensemble constraints including all imposed stresses and, most importantly, the deformation free energy of the adsorbent material. Consequently, a pressure-dependent PSD is a descriptor of the deformation characteristics of an adsorbent and may be the basis of future material characterization techniques. We discuss how, given a technique for resolving pressure-dependent PSDs, the present statistical mechanical theory could enable a new generation of analytical tools that measure and characterize certain intrinsic material properties of flexible adsorbents via otherwise simple adsorption experiments.
PubDate: 2017-05-01
DOI: 10.1007/s10450-017-9879-0
Issue No: Vol. 23, No. 4 (2017)

• Mechanism of adsorption of actives onto microporous functionalised calcium
carbonate (FCC)
• Authors: Charlotte L. Levy; G. Peter Matthews; Giuliano M. Laudone; Samuel Beckett; Andrew Turner; Joachim Schoelkopf; Patrick A. C. Gane
Pages: 603 - 612
Abstract: Microporous ‘functionalised’ calcium carbonate (FCC) has potential for use as a carrier for the controlled release of ‘actives’, by permeation and diffusion. We have investigated the nature of the FCC surface and the mechanism of adsorption of two typical actives, namely the anti-inflammatory drug aspirin and the flavour compound vanillin, from chloroform and aqueous ethanolic solutions. There is indirect evidence from the quantitative perturbation of Tóth isotherms that their adsorption is hindered by a stagnant diffusion layer of water trapped in the micro-porosity of the FCC. To complement previous studies of the surface of FCC, it was also tested with the cationic probe benzyltrimethylammonium bromide and the anionic probe sodium 2-naphthalenesulphonate. Experimental procedures were validated by comparison with adsorption onto ground calcium carbonate and high surface area talc.
PubDate: 2017-05-01
DOI: 10.1007/s10450-017-9880-7
Issue No: Vol. 23, No. 4 (2017)

• Modification of the surface chemistry of microdispersed sintered
detonation nanodiamonds and its effect on the adsorption properties
• Authors: S. N. Lanin; S. A. Rychkova; A. E. Vinogradov; K. S. Lanina; O. N. Obrezkov; P. N. Nesterenko
Abstract: Microdispersed sintered detonation nanodiamonds (MSDN) with different surface chemistry were characterized using X-ray diffraction method, energy dispersive spectroscopy (EDS) and adsorption of ionogenic and nonionogenic compounds in static and dynamic (with HPLC instrumental design) conditions. It was shown that for MSDN, conditioned with 3 × 10−3 M H3PO4, adsorption of substances with basic properties increases by 13.5–22.0, while washing of MSDN with 1.3 × 10−5 М ammonium hydroxide decreases adsorption of bases as a result of modification of ionic state of functional groups at the surface. It is found that concentration of H3PO4 solution significantly effects on adsorption of ionogenic organic substances. The effect of organic solvent is investigated by obtaining of isotherms of excessive adsorption of pyridine on MSDN from solutions in water and acetonitrile under static conditions. It is found that the equilibration of MSDN with acid solution activates its surface for adsorption of pyridine that may be due to desorption of substances blocking acidic adsorption centers. It was shown that usage of buffers containing additives of ammonium, potassium and sodium electrolytes results in decrease of adsorption of basic molecules, which is explained by competitive adsorption of cations on dissociated carboxyl functional groups on the surface of MSDN.
PubDate: 2017-05-16
DOI: 10.1007/s10450-017-9883-4

• Role of chemical structures in coalbed methane adsorption for anthracites
and bituminous coals
• Authors: Yongshuai Fu; Xianfeng Liu; Boqing Ge; Zhenghong Liu
Abstract: An in-depth investigation was conducted on four bituminous coals and three anthracites regarding the chemical structural characteristics using Fourier transform infrared spectroscopy (FTIR). The FTIR spectra of coals can be well approximated by the combination of Gaussian/Lorentzian peaks. FTIR parameters, including aromatic structures, aliphatic structures and oxygen-containing groups (C=O), were determined from curve-fitting analysis. Methane adsorption measurements were carried out through an equilibrium volumetric method, and the Langmuir equation was applied to fit the experimental data. Correlations were established for these FTIR structural parameters and methane adsorption parameters (V L and P L). From the results obtained, it can be seen that rapid changes occur for bituminous coals with the vitrinite reflectance, R o = 1.1–2.1%. The sharp variations of the apparent aromaticity, f a, and A(CH2)/A(CH3) indicate the significant intensive aromatization and the decrease of aliphatic methylene groups, respectively. As a consequence, the size of aromatic clusters is greatly enhanced with increasing coalification. However, the oxygen-containing functional groups, ´C´, varying from 0.43 for sample WJD to 0.10 for sample ZZ, presents a negative linear relationship with R o. Once R o > 2.1% (anthracite), both f a and A(CH2)/A(CH3) tend to be steady. The defects and degree of disorder in coal structure have been reduced to a large extent, and the graphite microcrystalline structure in coal is gradually perfected for anthracites. Coals with higher f a provide more adsorption sites for methane occupation on coal surface, thus demonstrating stronger adsorption capacities. However, the aliphatic methylene groups and oxygen-containing functional groups can decrease the CH4 adsorption amount at low pressure stage (<5 MPa), further reducing the adsorption properties. These findings may have great significance for accurate estimation reserves of coalbed methane and the prevention of gas disasters underground coal mine.
PubDate: 2017-05-03
DOI: 10.1007/s10450-017-9888-z

• Roll-up effect of sulfur dioxide adsorption on zeolites FAU 13X and LTA 5A
• Authors: Guanghui Li; Qishuai Wang; Tao Jiang; Jun Luo; Mingjun Rao; Zhiwei Peng
Abstract: The roll-up effect occurs as a result of the displacement of SO2 with H2O(g) when sulfur dioxide from humid flue gas is adsorbed by zeolites. It is mainly affected by SiO2/Al2O3 ratio (S/A) of zeolites, despite lack of detailed studies on use of hydrophilic zeolite. In this study, two zeolites of FAU 13X (S/A of 1.77) and LTA 5A (S/A of 1.51) were used to explore their roll-up effects using the breakthrough curve method. It is shown that the zeolite structure significantly influences the roll-up effect. The roll-up effect of FAU 13X is more significant than that of LTA 5A at the same water vapor content. The maximum roll-up ratio (η) for LTA 5A and FAU 13X are, respectively, 1.23 and 2.55 within the water vapor content range of 0.9–2.4%. Moreover, η of FAU 13X tends to decrease more rapidly than that of LTA 5A with increasing temperature or decreasing adsorption gas pressure. The presence of oxygen inhibits the roll-up effect and increases the breakthrough time of SO2. For the acid-modified zeolite, there is a positive correlation between η and concentration of Ca2+ or Na+ on zeolite surface, indicating obvious impact of cations on the roll-up effect.
PubDate: 2017-04-19
DOI: 10.1007/s10450-017-9887-0

• Selection of a stationary phase for the chromatographic separation of
organic acids obtained from bioglycerol oxidation
• Authors: Lucas C. D. Coelho; Nelson M. L. Filho; Rui P. V. Faria; Ana M. Ribeiro; Alírio E. Rodrigues
Abstract: A screening study of the chromatographic separation of Glyceric Acid (GCA) and Tartronic Acid (TTA) was performed using three different polystyrene-divinylbenzene ion-exchange resins in hydrogen form (Dowex® 50WX-8, Dowex® 50WX-4, Dowex® 50WX-2). The experiments were described by the axial dispersion flow model with the LDF approximation incorporated into the software gPROMS. From the three investigated adsorbents differing by the crosslinking, Dowex® 50WX-2 has presented the higher adsorption capacity, as well as the highest bed efficiency expressed by the number of theoretical plates. The adsorption equilibrium constants were determined from single breakthrough experiments, and a very good agreement between experimental and simulated data was achieved for both single components and binary mixtures. Therefore, the fundamental data determined within this work represents a key contribution to the design of continuous chromatographic processes for the purification of GCA and TTA.
PubDate: 2017-04-11
DOI: 10.1007/s10450-017-9882-5

• A robust dynamic column breakthrough technique for high-pressure
measurements of adsorption equilibria and kinetics
• Authors: Thomas Saleman; Gongkui Xiao; Gang Li; Eric F. May
Abstract: Adsorption equilibria and kinetics of N2 and CH4 on four adsorbents, namely commercial activated carbon Norit RB3, zeolite 13X, zeolite 4A and molecular sieving carbon MSC-3K 172, were measured at temperatures of (273 and 303) K in the pressure range of (25–900) kPa using an improved dynamic breakthrough apparatus. Equilibrium adsorption measurements were performed with breakthrough experiments, and sorption kinetics were measured with a chromatographic pulse technique to eliminate undesirable systematics such as buoyancy and limitations imposed by heat transfer in conventional breakthrough techniques. The differential equations governing the spreading of a pulse passing through the column were solved in the Laplace domain to reduce numerical dispersion and artefacts associated with solving these equations for adsorption in the time domain on a finite grid. A method for identifying the reliable measurement range of sorption rates (mass transfer coefficients) from 10−4 to 1 s−1 was proposed and demonstrated with the four adsorbents. The sorption rates for Norit RB3 and zeolite 13X had values above the upper resolvable limit of 1 s−1. The measured sorption rates for MSC-3K 172 and zeolite 4A were compared with values obtained independently using a static volumetric method on the same adsorbents at the same temperatures but over a lower pressure range (0–110 kPa) (Xiao et al., Adsorption 23 (2017) 131–147). The sorption rates obtained for the two adsorbents via these two independent techniques were consistent within the measurement uncertainty of each method, which significantly increases the confidence with which these values can be used in simulations of industrial PSA processes.
PubDate: 2017-04-09
DOI: 10.1007/s10450-017-9884-3

• Adsorption of laterally interacting gas mixtures on homogeneous surfaces
• Authors: F. O. Sanchez-Varretti; P. M. Pasinetti; F. M. Bulnes; A. J. Ramirez-Pastor
Abstract: The adsorption of binary mixtures containing particles A and B on homogeneous substrates is studied by Monte Carlo (MC) simulations, quasi-chemical approximation (QCA), and exact counting of states on finite cells (we call this approach cluster approximation, CA). The energies involved in the adsorption model are five: (1) $$\epsilon_A,$$ interaction energy between an A particle and a lattice site; (2) $$\epsilon_B,$$ interaction energy between a B particle and a lattice site; (3) $$w_{AA},$$ nearest-neighbor interaction energy between two A particles; (4) $$w_{AB}$$ (= $$w_{BA}$$ ), nearest-neighbor interaction energy between an A particle and a B particle and (5) $$w_{BB}$$ , nearest-neighbor interaction energy between two B particles. The process is monitored by following the coverage of both species with the simultaneous increasing of the individual chemical potentials of each mixture component. A non-trivial interdependence between the partial adsorption isotherms was observed and discussed in the context of the lattice-gas theory. The theoretical formalism is used to model experimental data of methane-carbon dioxide mixtures adsorbed on activated carbon. In addition, an excellent agreement was obtained between theoretical and MC simulation results. This finding evidences the usefulness of CA and QCA as a starting point to predict the behavior of a system governed by a large number of parameters.
PubDate: 2017-04-08
DOI: 10.1007/s10450-017-9885-2

• Orthogonal numerical simulation on multi-factor design for rapid pressure
• Authors: XinGang Zheng; Hua Yao; Yun Huang
Abstract: A two-dimensional model is established to simulate the rapid pressure swing adsorption (RPSA) process used for air separation with single bed. The model considers the transport phenomena occurring in both axial and radial direction. The decision variables include five factors (two heights of dead zone, durations of pressurization and adsorption steps, product extraction ratio), and the performance indexes consist of four variables (product purity, product recovery, bed size factor and average volume product yield). Based on an L16 (45) orthogonal design, 16 cases are arranged and the corresponding simulations are performed until the cycle steady states are reached from a given initial state. Range analysis is used to investigate the relative importance of the five factors on each performance index. Each factor’s optimal level and the corresponding combination is found out for each performance index successively.
PubDate: 2017-04-08
DOI: 10.1007/s10450-017-9886-1

• Results of comparative sorption studies of the coal-methane system carried
out by means of an original volumetric device and a reference gravimetric
instrument
• Authors: Mateusz Kudasik
Abstract: The present paper discusses the idea of an innovative device for sorption measurements, working under isobaric conditions and based on a precise piston pressure regulator. As part of the research, the author compared the results of sorption measurements obtained with the constructed piston sorptomat with the results obtained by means of a reference device. The sorption capacities of 15 granular high-volatile bituminous coal samples, determined on the basis of methane sorption courses registered with both instruments were compared. The author also defined the criterion of compatibility of the obtained results, which stated that the compared results are compatible if their values fall within the range of measurement uncertainties of the instruments with which they had been established. After comparing the results obtained with the original instrument with the results obtained with the reference gravimetric device, it was observed that 30 out of 33 measurements of sorption capacities were classified as compatible (based on the defined measurement compatibility criterion). The mean difference in the readings provided by both instruments was 1.64%, for sorption capacity determined in 33 measurement points and the methane pressure range of 1–10 bar.
PubDate: 2017-04-04
DOI: 10.1007/s10450-017-9881-6

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