ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (18)
  • adsorption  (18)
  • Springer  (18)
  • National Academy of Sciences
  • 1995-1999  (18)
  • 1975-1979
  • Process Engineering, Biotechnology, Nutrition Technology  (18)
  • Geography
  • 1
    Electronic Resource
    Electronic Resource
    Activity coefficients of adsorbed mixtures (1995)
    Springer
    Adsorption 1 (1995), S. 103-112 
    Details
    ISSN: 1572-8757
    Keywords: adsorption ; mixtures ; activity coefficients ; zeolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Experimental and simulated data for adsorption of gas mixtures on energetically heterogeneous surfaces like activated carbon and zeolites exhibit negative deviations from ideality. The deviations are large in some cases, with activity coefficients at infinite dilution equal to 0.1 or less. Similar molecules form ideal mixtures, but molecules of different size or polarity are nonideal. Equations for bulk liquid mixtures (Wilson, Margules, etc.) do not apply to isobars for adsorbed mixtures. A two-constant equation for activity coefficients as a function of composition and spreading pressure is in good agreement with theory, simulation, and experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00704999
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Molecular simulation of binary mixture adsorption in buckytubes and MCM-41 (1996)
    Springer
    Adsorption 2 (1996), S. 23-32 
    Details
    ISSN: 1572-8757
    Keywords: GCMC ; DFT ; adsorption ; MCM-41 ; buckytube ; simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract MCM-41 and buckytubes are novel porous materials with controllable pore sizes and narrow pore size distributions. Buckytubes are carbon tubes with internal diameters in the range 1–5 urn. The structure of each tube is thought to be similar to one or more graphite sheets rolled up in a helical manner. MCM-41 is one member of a new family of highly uniform mesoporous silicate materials produced by Mobil, whose pore size can be accurately controlled in the range 1.5–10 nm. We present grand canonical Monte Carlo (GCMC) simulations of single fluid and binary mixture adsorption in a model buckytube, and nonlocal density functional theory (DFT) calculations of trace pollutant separation in a range of buckytubes and MCM-41 pores. Three adsorbed fluids are considered; methane, nitrogen and propane. The GCMC studies show that the more strongly adsorbed pure fluid is adsorbed preferentially from an equimolar binary mixture. Ideal adsorbed solution theory (IAST) is shown to give good qualitative agreement with GCMC when predicting binary mixture separations. The DFT results demonstrate the very large increases in trace pollutant separation that can be achieved by tuning the pore size, structure, temperature and pressure of the MCM-41 and buckytube adsorbent systems to their optimal values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00127095
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Simulation of adsorption of liquid mixtures of N2 and O2 in a model faujasite cavity at 77.5 K (1996)
    Springer
    Adsorption 2 (1996), S. 41-50 
    Details
    ISSN: 1572-8757
    Keywords: Monte Carlo simulation ; Gibbs-Duhem integration ; adsorption ; liquid mixtures ; faujasite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Grand canonical Monte Carlo simulations of adsorption of N2 and O2 and their mixtures in a model zeolitic cavity 14 Å in diameter were performed at 77.5 K for pressures ranging from zero up to saturation, where the adsorbed phase is in equilibrium with coexisting vapor and liquid phases. The same intermolecular potential functions were employed for gas-gas interactions in the vapor, liquid, and adsorbed phases. The gas-solid interaction potential includes dispersion-repulsion energy, induced electrostatic energy, and an ion-quadrupole term to model the interaction of the electric field in zeolites like NaX with polar molecules like N2. The simulation of the coexisting vapor and liquid phases reproduces the saturation properties of pure liquid oxygen and nitrogen at 77.5 K. Activity coefficients in the adsorbed phase derived from simulations as a function of cavity filling and composition show negative deviations from Raoult's law, even though the non-idealities in the bulk liquid phase have the opposite sign. The simulation of the surface excess isotherm for adsorption from liquid mixtures exhibits preferential adsorption of N2 and has the commonly-observed quadratic shape skewed toward the more strongly adsorbed component. Micropore condensation is observed for oxygen but not for nitrogen. The condensation of oxygen is similar to a first order phase transition but because of the small number of molecules that can fit into a micropore, coexistence of the two phases is replaced by oscillations between gas- and liquid-like densities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00127097
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Molecular dynamics simulations of osmosis and reverse osmosis in solutions (1996)
    Springer
    Adsorption 2 (1996), S. 95-101 
    Details
    ISSN: 1572-8757
    Keywords: osmosis ; reverse osmosis ; adsorption ; diffusion ; molecular dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Computer simulation studies using the method of molecular dynamics have been carried out to investigate osmosis and reverse osmosis in solutions separated by semi-permeable membranes. The method has been used to study the dynamic approach to equilibrium in such systems from their initial nonequilibrium state. In addition density profiles of both the solute and solvent molecules have been investigated, especially near the walls for adsorption effects. Finally the diffusion coefficients and osmotic pressure have also been measured. Our results show both osmosis and reverse osmosis, as well as a smooth transition between the two when either the solution concentration is changed, or the density (pressure) difference between the solvent and solution compartments is varied. We believe this new method can be used to improve our understanding of these two important phenomena at the molecular level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00127103
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Adsorption and characteristics of base-treated pillared clays (1996)
    Springer
    Adsorption 2 (1996), S. 227-235 
    Details
    ISSN: 1572-8757
    Keywords: pillared clays ; heavy metal ions ; adsorption ; cation exchange capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The effect of base treatment on the cation exchange capacity (CEC) of pillared clays and their adsorption isotherms for Cu2+, Cr3+ and Pb2+ have been investigated. Results indicate that although the CEC of pillared clays are only about 15% of that of the parent clays, a large fraction of the native clays CEC may be recovered by treatment with base. The fraction of the CEC recovered depends upon the base strength, its concentration, and the temperature. Contrary to previous suggestions the mechanism of recovery is related to the destruction of pillars which is accompanied by the loss of surface area. It is possible under conditions specified to prepare these base treated pillared clays as a new class of useful, regenerable adsorbent for heavy metal adsorption from aqueous solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00128304
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Comparison of molecular simulation of adsorption with experiment (1996)
    Springer
    Adsorption 3 (1996), S. 107-115 
    Details
    ISSN: 1572-8757
    Keywords: adsorption ; molecular simulation ; isosteric heat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Experimental measurements of adsorption yield the surface excess. The Gibbs surface excess is the actual or absolute amount of gas contained in the pores less the amount of gas that would be present in the pores in the absence of gas-solid intermolecular forces. Molecular simulation of adsorption yields the absolute amount adsorbed. Comparison of simulated adsorption isotherms and heats of adsorption with experiment requires a conversion from absolute to excess variables. Molecular simulations of adsorption of methane in slit pores at room temperature show large differences between absolute and excess adsorption. The difference between absolute and excess adsorption may be ignored when the pore volume of the adsorbent is negligible compared to the adsorption second virial coefficient (V≪B 1s ).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01650234
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Theoretical basis for the Dubinin-Radushkevitch (D-R) adsorption isotherm equation (1997)
    Springer
    Adsorption 3 (1997), S. 189-195 
    Details
    ISSN: 1572-8757
    Keywords: Dubinin-Radushkevitch equation ; Dubinin-Astakhov equation ; adsorption ; micropore adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The Dubinin-Radushkevitch (D-R) equation, which was originally proposed as an empirical adaptation The Polanyi adsorption potential theory, has been the fundamental equation to quantitatively describe the adsorption gases and vapors by microporous sorbents. The equation, based on the postulate that the mechanism for adsorption in micropores is that of pore-filling rather than layer-by-layer surface coverage, generally applies well to adsorption systems involving only van der Waals forces and is especially useful to describe adsorption on activated ???. The ability of the D-R equation to describe gas adsorption on porous materials has inspired many to undertake studies, both experimental and theoretical, to explain the source of the success of the D-R equation in ??? of molecular properties at the gas-solid interface. In many cases, these studies have led to extensions or modifications of the original D-R equation. Many of these attempts and the resulting extensions are reviewed and discussed here. Recently, an isotherm equation was derived for adsorption of gases and vapors on microporous ??? from statistical mechanical principles. It was shown that the D-R equation is an approximated form of this potential theory isotherm. This development is also reviewed and discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01650130
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Adsorption of SO2 from Wet Mixtures on Hydrophobic Zeolites (1998)
    Springer
    Adsorption 4 (1998), S. 25-33 
    Details
    ISSN: 1572-8757
    Keywords: hydrophobic zeolites ; breakthrough curves ; adsorption ; binary mixtures ; modeling ; overall mass transfer ; roll-up
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Breakthrough curve measurements of SO2 and water vapor were carried out on a number of selected mordenite and pentasil zeolites from their binary and ternary mixtures with CO2 at 50 and 100°C. SO2 capacities of these samples were found to be significantly reduced by the presence of water. Competitive adsorption led to unusually high overshoot peaks of SO2 breakthrough curves. On the other hand, SO2 was found to displace water on the samples with very high silica to alumina ratio. A linear driving force, isothermal model was used to predict the breakthrough curves. Langmuir and extended Langmuir equilibrium models were used to describe the equilibrium properties of water and SO2, respectively. The overall mass transfer resistance obtained from the model was compared to the values calculated from a simplified biporous adsorbent model to shed some light on the adsorption kinetics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008883219403
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Neural Network Modeling of Adsorption of Binary Vapour Mixtures (1999)
    Springer
    Adsorption 5 (1999), S. 183-192 
    Details
    ISSN: 1572-8757
    Keywords: adsorption ; activated carbon ; neural network ; ideal adsorption solution theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Three neural network models were used for prediction of adsorption equilibria of binary vapour mixtures on an activated carbon. The predictions were compared both with published experimental data and calculated values from the Ideal Adsorption Solution (IAS) model. The neural network was trained using both binary and single component experimental adsorption data. Even for a limited number of data points (about 60) the network models were capable of approximating experimental data very precisely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008977528474
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Pressure Effects in Adsorption Systems (1999)
    Springer
    Adsorption 5 (1999), S. 261-278 
    Details
    ISSN: 1572-8757
    Keywords: adsorption ; concentrated systems ; pressure transients ; flow transients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A study of the occurrence of large pressure and flow transients when a strongly adsorbed gas is fed to a column which is initially loaded with a lightly adsorbed gas is presented here. Under certain conditions, these transients can cause premature breakthrough and change the shape of the breakthrough curve. This will result in improper estimation of adsorption parameters by the dynamic column loading method and lower apparent adsorption capacity in a full scale unit. A data acquisition system was used to record the pressure and flow transients. An isothermal PDE model developed to study these transients agreed reasonably well with the nonisothermal experimental results. The PDE model predicts that pressure and flow transients will occur during step and pulse~tests conducted to obtain adsorption and mass transfer parameters by the chromatographic method. For instance, lower adsorption capacity will be realized during step tests due to lowering in column pressure. Oscillations were observed when columns are connected in series. The PDE model also predicts these oscillations. Simulations indicate that the extent of oscillations is dependent on the dead volume between columns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008955828900
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    An ultrastructural study of the interaction of a fungal endoglucanase from Humicola insolens with cotton fibres (1997)
    Springer
    Cellulose 4 (1997), S. 7-20 
    Details
    ISSN: 1572-882X
    Keywords: cellulase ; cottonfibres ; electron microscopy ; biopolishing ; adsorption ; colloidalgold labeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Because cellulases are finding more applications in the textile and detergent industries, their effect on cotton fibres must be evaluated. For this purpose, the action of a recombinant cellulase, endoglucanase V from the fungus Humicola insolens, has been followed by scanning electron microscopy (SEM) in classical longitudinal views as well as in cross-sections of cotton fibres. The experiments were conducted at large enzyme dilution typical of conditions where cellulases are used for biopolishing, i.e. for the removal of defects created by mechanical abrasion. Endoglucanase V appears to restrict its action to the hydrolysis of the loose fibrils created at the surface of the fibres and no indication of extensive enzyme penetration and damage to the interior of the fibres could be detected by SEM. The adsorption sites for endoglucanase V on cotton fibres were examined by transmission electron microscopy (TEM) on ultrathin cross-sections after immuno-gold labeling of the enzyme. This approach showed that the enzymes did not penetrate the fibres but remained at their surface. The use of an immuno-gold labeled cellulase provides a new way to probe the surface features of cotton fibres
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018454900127
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Sorption Equilibria and Kinetics of Hydrocarbons onto Activated Carbon Samples Having Different Micropore Size Distributions (1999)
    Springer
    Adsorption 5 (1999), S. 25-37 
    Details
    ISSN: 1572-8757
    Keywords: micropore size distribution ; activated carbon ; adsorption ; desorption ; equilibrium ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract This paper deals with the prediction of adsorption equilibrium and kinetics of hydrocarbons onto activated carbon samples having different micropore size distribution (MPSD). The microporous structure of activated carbon is characterised by the distribution of slit-shaped micropores, which is assumed to be the sole source of surface heterogeneity. The interaction between adsorbate molecule and pore walls is described by the Lennard-Jones potential theory. Different adsorbates have access to different pore size range of activated carbon due to the size exclusion, a phenomenon could have a significant influence on both multicomponent equilibria and kinetics. Activated carbons with three different MPSDs are studied with ethane and propane as the two model adsorbates. The Heterogeneous Macropore Surface Diffusion model (HMSD) is employed to simulate adsorption kinetics. The simulation results show that the MPSD is an important factor affecting both the multicomponent equilibria and kinetics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026481704926
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Adsorption of a Trichoderma reesei endoglucanase and cellobiohydrolase onto bleached Kraft fibres (1997)
    Springer
    Cellulose 4 (1997), S. 255-268 
    Details
    ISSN: 1572-882X
    Keywords: biotechnology ; cellulase ; endoglucanase ; cellobiohydrolase ; adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Cellulases can be used to modify pulp fibres. For the development of biotechnical applications, a better understanding of the adsorption of cellulases onto commercial wood fibres is needed. In this work, the adsorption behaviour of purified CBH I and EG II on bleached Kraft fibres was investigated. Three variables were studied with respect to their effect on adsorption: fibre type (hardwood or softwood), fibre history (never-dried or once-dried), and ionic strength. The results showed that fibre history had the largest influence on the extent of adsorption of each enzyme. The effect of ionic strength was shown to be dependent on the enzyme and fibre type. At high ionic strength, CBH I exhibited a higher affinity for both once-dried and never-dried fibres at low enzyme concentrations; however, salt was shown to decrease the extent of adsorption at higher enzyme dosages. In contrast, salt increased the maximum adsorption of EG II, most notably on the once-dried hardwood fibres. Fibre type was also shown to affect adsorption behaviour. CBH I had a higher affinity for softwood fibres than for hardwood fibres at low enzyme concentrations. The maximum adsorption of EG II onto once-dried softwood fibres increased by 80% compared to the once-dried hardwood fibres. Interestingly, this did not correlate to in creased fibre hydrolysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018444008305
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    A Study of Adsorption of Water Vapour on Wool under Static and Dynamic Conditions (1998)
    Springer
    Adsorption 4 (1998), S. 63-73 
    Details
    ISSN: 1572-8757
    Keywords: wool ; water vapour ; adsorption ; diffusion ; column dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Adsorption of water vapour on wool provides not only textile comfort, but also convenience in transportation due to increase in its bulk density. The adsorption and desorption isotherms of water vapour for wool were determined by both volumetric technique using a Coulter Omnisorp 100CX instrument and gravimetric method employing a Cahn 2000 electronic microbalance. Adsorption isotherm fitting to B.E.T. model and hysteresis on desorption was observed. The average effective diffusion coefficient of water in wool was found to be 8.4 × 10-14 m2s-1 at 25°C from gravimetric data. The effects of packing height and air velocity on the breakthrough curves were also investigated in the wool packed columns. For pseudo first order model, k values changing between 0.33 × 10-6 − 69 × 10-6 s-1 was obtained for 2.2–6.4 cm s-1 air velocity and 0.05–0.20 m packing height ranges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008839404382
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Effects of Surface Oxygen of Activated Carbon on Alkaloid Adsorption: A Molecular Dynamics Simulation Study (1999)
    Springer
    Adsorption 5 (1999), S. 97-108 
    Details
    ISSN: 1572-8757
    Keywords: adsorption ; molecular simulation ; activated carbon ; surface oxygen ; alkaloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The influence of the density and the type of surface oxygen on the adsorption of berberine alkaloid onto activated carbon was investigated using the molecular dynamics simulation method in vacuum. The carbon surface consisted of a basal plane of graphite and surface oxygen groups which were bonded on the graphite plane in a regular square array with various densities. Two types of surface oxygen groups, =O and —OH, were employed. The simulation results showed that the berberine alkaloids were favorable to be adsorbed on the negative charged carbon surfaces. It was indicated that the vdw attraction of the carbon surface to the alkaloid molecule dominates the adsorption only at the lower surface density of oxygen. It is also indicated that a good adsorptive selectivity for a certain berberine alkaloid can be obtained by controlling the density of surface oxygen. The adsorption simulation of berberine alkaloids onto activated carbon in the presence of water was also carried out by using a dome-shape molecular model for presenting the alkaloid/water/carbon system. It was found that the adsorption of berberine alkaloids on the activated carbon which has a higher density of surface oxygen was strongly inhibited by the presence of water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026479130851
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Pure and Binary Gas Adsorption Equilibria and Kinetics of Methane and Nitrogen on 4A Zeolite by Isotope Exchange Technique (1999)
    Springer
    Adsorption 5 (1999), S. 145-158 
    Details
    ISSN: 1572-8757
    Keywords: kinetics ; isotope-exchange ; nitrogen ; adsorption ; methane ; zeolite ; equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The Isotope Exchange Technique (IET) was used to simultaneously measure pure and binary gas adsorption equilibria and kinetics (self-diffusivities) of CH4 and N2 on pelletized 4A zeolite. The experiment was carried out isothermally without disturbing the adsorbed phase. CH4 was selectively adsorbed over N2 by the zeolite because of its higher polarizability. The multi-site Langmuir model described the pure gas and binary adsorption equilibria fairly well at three different temperatures. The selectivity of adsorption of CH4 over N2 increased with increasing pressure at constant gas phase composition and temperature. This curious behavior was caused by the differences in the sizes of the adsorbates. The diffusion of CH4 and N2 into the zeolite was an activated process and the Fickian diffusion model described the uptake of both pure gases and their mixtures. The self-diffusivity of N2 was an order of magnitude larger than that for CH4. The pure gas self-diffusivities for both components were constants over a large range of surface coverages (0 〈 θ 〈 0.5). The self-diffusivities of CH4 and N2 from their binary mixtures were not affected by the presence of each other, compared to their pure gas self-diffusivities at identical surface coverages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008917308002
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Impedance Spectroscopic Measurements of Pure Gas Adsorption Equilibria on Zeolites (1999)
    Springer
    Adsorption 5 (1999), S. 159-167 
    Details
    ISSN: 1572-8757
    Keywords: impedance spectroscopy ; uptake curve ; adsorption ; polarization of adsorbate ; dielectric properties of adsorbed phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Physisorption equilibria of gases on inert porous solids like activated carbon or molecular sieves can be characterized by measuring the (frequency dependent) capacitance of a capacitor filled with a sample adsorbent. This quantity strongly depends not only on the physico-chemical structure of the empty adsorbent in vacuum, but also on the permanent or induced dipole moments of the molecules adsorbed and of the fluid phase. Consequently, it should be possible to determine the excess mass being adsorbed on the internal surface of a highly porous solid by measurements of the dielectric constant. The aim of this work is to show for various pure gases and adsorbents that the change of the capacitance of an adsorption system depends on the adsorbed mass. Therefore, this effect can be used to characterize porous solids and their adsorbates and, for example, to check the state or the quality of industrial adsorbents during a process on site if calibration measurements have been taken (Staudt et al., 1994, 1998).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008969308910
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Liquid Phase Separation of Polar Hydrocarbons from Light Aromatics Using Zeolites (1999)
    Springer
    Adsorption 5 (1999), S. 399-407 
    Details
    ISSN: 1572-8757
    Keywords: zeolites ; polar compounds ; adsorption ; adsorption isotherms ; equilibrium ; liquid phase ; breakthrough curves ; acetonitrile ; acrylonitrile ; dioxane ; ZSM-5 ; MCM-22 ; Na-X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The liquid phase removal of low concentrations of polar compounds (acetonitrile, acrylonitrile and dioxane) from toluene by adsorption on zeolites reveals very high selectivity factors. Kinetic selectivity factors as high as 16,100 are observed. The selection of the zeolites (MFI, MWW and FAU type) allowed the study of the effects of varying aluminum content, the presence and absence of acidic centers and varying pore volumes. To assess the relative effectiveness of each adsorbent, both equilibrium and continuous flow, pseudo equilibrium, breakthrough experiments were conducted. The continuous flow experiments were carried out at 25 and 75°C. The zeolites H-ZSM-5, H-MCM-22 and Na-X are highly effective in removing the polar compounds from toluene to a concentration level down to less than 20 ppm (detection limit). The results obtained with the equilibrium batch experiments are confirmed by the continuous flow breakthrough experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008916917943
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...