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  • Articles  (44)
  • adsorption  (44)
  • Springer  (44)
  • American Meteorological Society
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  • 1995-1999  (28)
  • 1990-1994  (16)
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  • 1996  (28)
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  • Chemistry and Pharmacology  (44)
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  • Articles  (44)
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  • Springer  (44)
  • American Meteorological Society
  • National Academy of Sciences
  • Wiley-Blackwell  (9)
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  • 1995-1999  (28)
  • 1990-1994  (16)
  • 1965-1969
  • 1955-1959
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  • 1
    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
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  • 2
    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
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  • 3
    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
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  • 4
    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
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  • 5
    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
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  • 6
    Electronic Resource
    Electronic Resource
    Relation between preparation, porosity and selectivity of CuO-ZnO-MeO x catalysts in the synthesis of alcohol mixtures (1992)
    Springer
    Catalysis letters 14 (1992), S. 185-195 
    Details
    ISSN: 1572-879X
    Keywords: CuO-ZnO-MeO x catalysts ; characterization by XRD ; DTA ; adsorption ; alcohol synthesis ; C2-C5-OH selectivity ; influence of porosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Some relations between the preparation of modified CuO-ZnO catalysts, their structural properties and their catalytic performance in the hydrogenation of carbon monoxide have been demonstrated. The different activities in the formation of higher alcohols have been attributed to an influence of the porosity on chain growth. The coupling or insertion of C1 intermediates seems to be favoured by an increasing surface coverage with C1 intermediates due to a transport limitation of methanol production. The pore size distribution of the catalysts has been varied by different calcination, thermal ageing, CuO/ZnO ratios, the method of promoting with Al2O3 and pelleting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00765232
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  • 7
    Electronic Resource
    Electronic Resource
    Accumulation of zinc and cadmium by Cytophaga johnsonae (1996)
    Springer
    BioMetals 9 (1996), S. 169-175 
    Details
    ISSN: 1572-8773
    Keywords: bacteria ; adsorption ; uptake ; metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Passive and active accumulation of zinc and cadmium by a common soil and freshwater bacterium, Cytophaga johnsonae, was studied using a radio-tracer batch distribution technique. The effects of variation of pH (3–10), as well as of ionic strength (0.007 and 0.07 m) on passive accumulation of the metals were examined. For both zinc and cadmium, accumulation was mainly due to passive processes, such as surface adsorption and/or diffusion into the periplasm. However, at low zinc concentrations, accumulation increased when glucose was added, suggesting an active uptake; at higher zinc concentrations such uptake was not detected, probably because it was masked by the stronger sorption properties of the cell wall. Adsorption of the metals was pH dependent: at higher ionic strength, accumulation was enhanced at pH values above 7; at lower ionic strength, adsorption differed and was markedly higher, with increased accumulation between pH 5 and 8.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00144622
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  • 8
    Electronic Resource
    Electronic Resource
    FTIR spectroscopic and1 H MAS NMR studies of the influence of lattice chemistry and structure on Brønsted acidity in zeolites (1996)
    Springer
    Catalysis letters 39 (1996), S. 147-152 
    Details
    ISSN: 1572-879X
    Keywords: Brønsted acidity ; FTIR ; 1 H MAS NMR ; adsorption ; zeolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of the Si/Al ratio, of the nature of the T-atom and of the pore size on the acidic strength of Brønsted sites in zeolites has been investigated using changes of the vibrational properties of Brønsted OH(OD) groups and a shift change of Brønsted protons in nuclear magnetic resonance upon adsorption of weak bases. Deuterated acetonitrile and trichloro-acetonitrile have been chosen to probe the acidic strengths of ZSM-5, FeZSM-5, mordenite and zeolite Y, which are often used as catalysts. From the results of the FTIR and 1 H MAS NMR studies it can be concluded that the chemical composition of the lattice dominates the acidic strength of the Brønsted sites in zeolites. Differences in structure or pore size play a much smaller role.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00805574
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  • 9
    Electronic Resource
    Electronic Resource
    A density functional study of molecular adsorption in zeolites (1996)
    Springer
    Topics in catalysis 3 (1996), S. 169-194 
    Details
    ISSN: 1572-9028
    Keywords: density functional theory ; zeolites ; adsorption ; hydrogen bonding ; water ; methanol ; ammonia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Non-local density functional theory has been used to investigate the adsorption of water, methanol and ammonia on cluster representations for zeolites. Only in the case of ammonia is the chemisorbed ion pair complex found to be a minimum, while binding energies are close to the lower bounds of experimental values. Large frequency shifts are found for hydroxyl stretching modes, particularly as the loading of adsorbate is increased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02431184
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  • 10
    Electronic Resource
    Electronic Resource
    A microcalorimetric study of the different states of argon and nitrogen adsorbed AT 77 K on silicalite-I and ZSM-5 (1992)
    Springer
    Journal of thermal analysis and calorimetry 38 (1992), S. 683-692 
    Details
    ISSN: 1572-8943
    Keywords: adsorption ; microcalorimetry ; zeolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Mittels Mikrokalorimetrie, Volumetrie und Neutronendiffraktion wurde die Adsorption von Argon und Stickstoff an einer Reihe von MFI-Zeolithen ((Si/Al1000) und HZSM-5 (16〈Si/Al〈120)). Die Adsorption von Argon und Stickstoff stellt einen Phasenübergang von einem “flüssigkeitsartigen” zu einem “feststoffartigen” Adsorbat dar. Die “feststoffartigen” Strukturen beider Adsorbate sind einander ähnlich und durch das Zeolith-Tunnelsystem geprägt. Die Erhöhung des Aluminiumgehaltes verursacht bei Stickstoff eine allgemeine Zunahme der belegten Adsorptionsstellen, während das Verhalten von Argon unverändert bleibt. An HZSM-5 vollzieht sich zwar die Phasenumwandlung bei beiden Adsorbaten, aber — insbesondere bei Stickstoff — durch Erhöhung des Aluminiumgehaltes in einer weniger ausgeprägten Weise.
    Notes: Abstract The adsorption of argon and nitrogen on a series of MFI-type zeolites (silicalite-I (Si/Al〉1000) and HZSM-5 (16〈Si/Al〈120)) was studied by isothermal microcalorimetry, volumetry and neutron diffraction. The adsorption of argon and nitrogen present a ‘liquid-like’ to ‘solid-like’ adsorbate phase change. The ‘solid-like’ structures of both adsorbates are similar and imposed by the zeolite channel system. Increasing the aluminium content produces an overall increase in the enhanced adsorption sites for nitrogen whereas the behaviour of argon is unmodified. On HZSM-5, the phase changes of both adsorbates still occur, but, particularly for nitrogen, in a less distinct manner with increasing aluminium content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01979397
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  • 11
    Electronic Resource
    Electronic Resource
    Calorimetric investigations on molecular interactions in a mixed layer adsorbed on a homogeneous surface (1992)
    Springer
    Journal of thermal analysis and calorimetry 38 (1992), S. 2033-2039 
    Details
    ISSN: 1572-8943
    Keywords: adsorption ; calorimetry ; differential heats of adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurde die Adsorption und die differentiellen Adsorptionswärmen äqnimolarer Gemische aus Methanol mit Tetrahydrofuran bzw. aus Methanol und Tetra-hydrofuran mit Cyclopentan (Molverhältnis 1∶1 bzw. 1∶4) an mit Graphit überzogenen Ruß Sterling MT Oberflächen bestimmt. Dabei wurde die Abhängigkeit der intermolekularen Wechselwirkungen von der Zusammensetzung der adsorbierten Schicht aufgedeckt. Ausgehend von der Analyse der experimentellen Ergebnisse wurde der Mechanismus der Adsorption eines Methanol-Tetrahydrofurangemisches beschrieben, wobei sowohl homoals auch heteromolekulare Assoziation berücksichtigt wurde.
    Notes: Abstract The adsorption and differential heats of adsorption of mixtures of methanol and tetrahydrofuran (mole ratio 1∶1), methanol and cyclopentane (1∶1 and 1∶4) and tetrahydrofuran and cyclopentane (1∶1 and 1∶4) on a graphitized carbon black (Sterling MT) surface were determined. The dependence of the intermolecular interactions on the composition of the adsorbed layer was established. From an analysis of the experimental results, the mechanism of adsorption of the equimolar methanol-tetrahydrofuran mixture was described, in which both homomolecular. and heteromolecular association were taken into consideration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01979615
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  • 12
    Electronic Resource
    Electronic Resource
    Adsorption from ternary liquid mixtures on silica gel and aluminium oxide (1996)
    Springer
    Journal of thermal analysis and calorimetry 46 (1996), S. 417-429 
    Details
    ISSN: 1572-8943
    Keywords: adsorption ; aluminium oxide ; silica gel ; ternary mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Formation of mixed adsorbed layers was tested for ternary liquid mixtures containing methanol or acetone and the binary solvent benzene+n — heptane. The specific excess adsorption isotherms from the liquid phase were measured on silica gel, silanized silica gel and aluminium oxide. The experimental adsorption data are discussed on the basis of the changes in the mixed solvent composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02135019
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  • 13
    Electronic Resource
    Electronic Resource
    In-vitro protein interactions with a bioactive gel-glass (1996)
    Springer
    Journal of sol gel science and technology 7 (1996), S. 69-76 
    Details
    ISSN: 1573-4846
    Keywords: sol-gel ; bioactive ; protein ; adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Recent theories suggest that the local adsorption of biologically active peptide growth factors onto the surface of an implant may contribute to the unique osteogenic nature of silica-containing bioactive ceramics. A sol-gel derived glass is used as a model of the in-vivo reaction product of 45S5 bioactive glass at relatively short times (〈48 hrs.) to investigate protein adsorption/desorption behavior. The adsorption kinetics of three heme-class proteins (cytochrome c, myoglobin, and hemoglobin) are measured spectroscopically. The rate of adsorption is shown to increase with average pore size, which is determined by the silica content of the gel. Adsorption rate decreases as protein size is increased and as solution pH is decreased. Biological function of an adsorbed peroxidase enzyme on pre-reacted Bioglass® is shown to be retained. Desorption during physiologic conditions is shown to be linear with time and pH dependant, while independent of gel bioactivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00401885
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  • 14
    Electronic Resource
    Electronic Resource
    Reaction of nitrogen oxides with salts of metal-substituted heteropolyanions (1992)
    Springer
    Russian chemical bulletin 41 (1992), S. 1526-1530 
    Details
    ISSN: 1573-9171
    Keywords: nitrogen oxides ; adsorption ; nitrosyl complexes ; iron ; metal-substituted heteropolyanions ; IR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We have used IR spectroscopy to study the reaction with NO and NO2 of solid tetramethylammonium and cesium salts of heteropolyanions (HPA) PW11M(L) 0.39 n− [M=V(V), Cr(III), Mn(II), Fe(II, III), Co(II), Ni(II), Cu(II); L=H2O, OH− or O2−], preevacuated at 110°C or 300°C. Only in the case of Fe(II)-substituted heteropolyanions are nitrosyl complexes formed: PW11Fe(NO)O 39 5− (vNO=1730 cm−1), which leads to stabilization of the NO molecules with respect to oxidation by oxygen. We observed reversible reaction with NO2 by the listed heteropoly complexes. The vibrational frequencies of adsorbed NO2 are virtually independent of the metal M and its coordination environment in the heteropolyanion (v1=1335−1360) and v3=1620−1640 cm−1). This provides a basis for assuming that the NO2 groups are bonded to the oxygen atoms in the heteropoly anion with formation of the fragments OHPA...NO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00863565
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  • 15
    Electronic Resource
    Electronic Resource
    ESR study of electron interaction in a Tc/Al2O3 system (1992)
    Springer
    Russian chemical bulletin 41 (1992), S. 1531-1536 
    Details
    ISSN: 1573-9171
    Keywords: technetium ; aluminum oxide ; paramagnetic centers ; ESR ; adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An investigation was made into the nature of paramagnetic centers in a Tc/Al2O3 system under varying conditions as to heat treatment and technetium content, and in O2 and CO adsorption environments. It was found that in the case of reduction at 573 K Tc2+ ions and, conceivably, other ionic forms developed and stabilized on the carrier surface. After reduction at 973 K two types of electron center appeared, whose concentration increased as reduction was prolonged. Signals were observed in the low fields (3–20 mT) of the ESR spectra having g1 ≈ 13.5 and g2〉30, which could be assigned to free charge carriers in a cluster of metal atoms or ions. Adsorption of O2 at 300 K caused O 2 − ion radicals to form on the surface of the reduced Tc/Al2O3 samples, both electron centers and technetium ions constituting the electron donors. In the case of CO adsorption paramagnetic (CO) 2 − particles appeared on the Tc/Al2O3 samples after prolonged exposure. On reaction with O2 two types of O 2 − ion-radical with differing thermal stability were formed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00863566
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  • 16
    Electronic Resource
    Electronic Resource
    Investigation of the surface of Ni-Pd catalysts by IR spectroscopy (1992)
    Springer
    Russian chemical bulletin 41 (1992), S. 992-996 
    Details
    ISSN: 1573-9171
    Keywords: IR spectroscopy ; adsorption ; carbon monoxide ; bimetallic deposited catalysts ; nickel ; palladium ; aluminum oxide ; promoter ; potassium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reaction of carbon monoxide with the surface of Ni, Pd, and Ni-Pd catalysts, deposited on γ-Al2O3, was investigated at 25°C by IR spectroscopy in conjunction with an adsorption volumetric technique. The IR spectra contained the following absorption bands (v, cm−1): 2020–2100 (AB1) (linear and subcarbonyl forms of adsorbed CO); 1945–1985 (AB2) (bridging); 1920–1940 (AB3) with a shoulder at 1870–1885 (AB4) (bridging and many-center). In the spectrum of Ni the absorption band AB5 appears at 1770–1780 (CO-Ni+). It appears with surface coverage a ≥ 1.3 mole CO/mole εM. The optical density (A) of AB1 for Ni97Pd3 is appreciably higher than for the other investigated samples. In the Ni-Pd catalysts the intensity of AB2 in relation to AB1 is higher than in nickel. The introduction of K+ ions into the support of the bimetallic sample reduces the optical density of AB1. In modified Ni-Pd-K the AB3 and AB4 bands disappear.
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    URL: http://dx.doi.org/10.1007/BF00866571
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  • 17
    Electronic Resource
    Electronic Resource
    Adsorption deformation of zeolite NaX at high pressures of xenon (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 321-323 
    Details
    ISSN: 1573-9171
    Keywords: adsorption ; zeolite, crystal deformation ; high pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The deformation of pellets of crystalline zeofite NaX upon adsorption of Xe at pressures from 0.001 to 7 MPa and temperatures from 252.5 to 333 K was studied. In the temperature range studied, the relative linear deformation of zeolite crystals is negative in the initial adsorption region. When the adsorption of Xe increases, its value passes through a minimum and then increases sharply taking positive values at high adsorption volume filling of micropores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01433964
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  • 18
    Electronic Resource
    Electronic Resource
    Adsorption phenomena at high pressures and temperatures. (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 534-538 
    Details
    ISSN: 1573-9171
    Keywords: adsorption ; radius of a molecule ; adsorbent ; surface ; pore volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Equilibrium adsorption isotherms for Ar, Kr, and N2 on crystalline NaA zeolite were measured in the pressure range of 0.1–160 MPa and temperature range of 305–448 K. The method for determining the inaccessible volume of the adsorption system (free volume + micropore volume) and the micropore volume of a sorbent with the use of such adsorbates as monoatomic Ar and Kr and diatomic N2 was applied. The effective radii of N2 and O2 molecules were calculated from the dependence of micropore volume of the zeolite on the radius of the monoatomic gas used. On the basis of this result, one can determine the orientation of the molecules of nitrogen and oxygen in the pores of the zeolite, caused bysorption forces. The use of Ar and Kr as the adsorbates allows one to determine the total surface area of the zeolite, which was found to be equal to 1458 M2/g.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01435776
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  • 19
    Electronic Resource
    Electronic Resource
    The influence of low-temperature oxidation of active carbons by nitric acid on their physicochemical properties (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 1071-1077 
    Details
    ISSN: 1573-9171
    Keywords: active carbons ; oxidation ; surface chemistry ; n-hexane ; water ; methanol ; adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of oxidation by nitric acid on the character of oxygen-containing functional surface groups and porous structure of active carbons is considered. Adsorption properties of the initial and oxidized carbons are studied using adsorption isotherms of vapor of n-hexane and polar substances (water and methanol).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01431592
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  • 20
    Electronic Resource
    Electronic Resource
    Adsorption of helium on zeolite NaA (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 1230-1231 
    Details
    ISSN: 1573-9171
    Keywords: helium ; adsorption ; zeolite NaA ; adsorption isotherm ; adsorption heat ; Henry constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Isotherms of helium adsorption on zeolite NaA were measured by the volumetric method under static conditions at 23–50 K and pressures from 1 Pa to 65 kPa. The Henry constants and the initial heat of helium adsorption were calculated; the isosteric heat was calculated, and its dependence on the adsorption was determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01431627
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  • 21
    Electronic Resource
    Electronic Resource
    IR spectroscopic study of the adsorption of MeOH and H2O on decationized zeolites (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 1307-1311 
    Details
    ISSN: 1573-9171
    Keywords: decationized zcolitcs ; adsorption ; IR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The IR spectra of decationized zeolites with adsorbed bases have been analyzed. A correlation between the shift Δη(OH) of the center of gravity of the set of bandsA,B, andC (components of the η(OH) vibration) and the strength of the H-bond between the bridging hydroxyl groups and the molecule of a base has been found. This is evidence in support of the Fermi-resonance nature of the perturbations of the η(OH) vibration. Spectral data on the adsorption of H2O and MeOH on decationized zcolitcs that cannot be interpreted in terms of the formation of complexes with strong H-bonds have been obtained. Arguments in favor of the formation of H3O+ and MeOH2 + ions linked to the neighboring oxygen atoms in the zeolitc latticevia two identical hydrogen bridges have been presented.
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    URL: http://dx.doi.org/10.1007/BF01434202
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    Structure of polynuclear palladium(II) hydroxocomplexes and the mechanism of their adsorption by carbon materials (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 1296-1302 
    Details
    ISSN: 1573-9171
    Keywords: palladium hydrolysis ; polynuclear hydroxocomplexes (PHC) ; carbon material ; adsorption ; radial atomic distribution method ; X-ray phase analysis ; electron microscopy ; molecule structure modeling ; synthesis of microscopic images
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Adsorption of polynuclear palladium(ii) hydroxocomplexes (PHC) by carbon materials (CM) was studied. It was found that PHC are adsorbed from aqueous solutions without a change in their chemical composition and are composed of clusters (〈10 A) with metalmetal distances typical of the PdO chain structure. Three-dimensional ordered particles with the PdO structure were formed upon adsorption of PlIC on carbon materials at room temperature or after the PHC suspension was dried in air at 400 °C (the size of the particles was 15 and 25 A, respectively). Calculation of the electron-microscopic images of the adsorbed PHC with atomic resolution based on crystal structure modeling showed that PdO particles containing -100 palladium atoms is the final product after drying of the adsorbed PHC.
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    URL: http://dx.doi.org/10.1007/BF01434200
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    Adsorption phenomena at high pressures and temperatures 5. Heats of excess and total adsorption of krypton on zeolite NaA (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 1844-1848 
    Details
    ISSN: 1573-9171
    Keywords: adsorption ; differential heats ; excess adsorption ; absolute adsorption ; high pressures and temperatures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermodynamic principles for the calculation of differential heats of excess and absolute adsorption were considered. A set of isosteres of excess adsorption of krypton on zeolite NaA are presented, from which the coverage and temperature dependences of the heats of excess adsorption are calculated and analyzed. The reasons for infinitely high values of the excess heats at finite values of adsorption are discussed. The problems of recalculation of the excess adsorption to absolute adsorption are considered.
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    URL: http://dx.doi.org/10.1007/BF01457761
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    Modification of the theory of a three-dimensional filling of micropores (1992)
    Springer
    Russian chemical bulletin 41 (1992), S. 5-9 
    Details
    ISSN: 1573-9171
    Keywords: adsorption ; adsorption volume ; compressibility ; activated carbon ; benzene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Compressibility of the adsorbate has been taken into account in calculating the maximum adsorption in micropores. On this basis, an equation has been derived for improvement of the theory of three-dimensional filling of micropores in application to the calculation of micropore volume by the Dubinin-Radushkevich equation. Evaluations for the case of benzene adsorption on activated carbons at ∼20°C have shown that the accounting for adsorbate compressibility leads to corrections of the Dubinin-Radushkevich theory amounting to approximately 10%.
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    URL: http://dx.doi.org/10.1007/BF00863901
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    Temperature dependence of sorptive deformation (1992)
    Springer
    Russian chemical bulletin 41 (1992), S. 14-18 
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    ISSN: 1573-9171
    Keywords: adsorption ; zeolites ; temperature dependence ; deformation of crystals ; isotherms ; isosteres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A study has been made of the temperature dependence of deformation of CaA, CaX, and LaX zeolites when krypton or xenon is adsorbed, and also the deformation of activated carbon when dimethyl ether is adsorbed. It has been shown that the volume compressibility and the standard chemical potential of the adsorbate in a vacancy solution, within the interval of temperatures and pressures that were investigated, can be considered as linear functions of temperature. In this case, knowledge of the temperature dependence of sorptive deformation offers a means for calculating sorptive deformation curves for other temperatures.
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    URL: http://dx.doi.org/10.1007/BF00863903
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    Cobalt/silica gel system as a chemisorbent for oxygen (1992)
    Springer
    Russian chemical bulletin 41 (1992), S. 28-31 
    Details
    ISSN: 1573-9171
    Keywords: adsorption ; oxygen ; gas purification ; reduction ; phase composition ; catalyst
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A study has been made of oxygen chemisorption and the phase composition of cobalt/silica gel samples containing from 1.1 to 7.7% Co by weight. Reduction in hydrogen leads to the formation of metallic cobalt with a crystal size of about 50 Å. The quantity of chemisorbed O2 at 20°C increases in proportion to the increase of [Co]. The uptake of O2 is essentially completed at 300°C with the formation of Co3O4. The high adsorption capacity for O2 is preserved unchanged in repetitive reduction-oxidation cycles. The residual content of O2 in the gas after passage through the layer of the cobalt/silica gel chemisorbent is 3·10−6% by volume.
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    URL: http://dx.doi.org/10.1007/BF00863906
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    Two methods of describing adsorption equilibrium (1992)
    Springer
    Russian chemical bulletin 41 (1992), S. 10-13 
    Details
    ISSN: 1573-9171
    Keywords: adsorption ; differential heat of adsorption ; deformation of adsorbent
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The thermodynamics of adsorption equilibrium with a single-component gas phase have been analyzed for two different models of adsorption. It has been shown that with a cell model of adsorption, the differential energy of the adsorbent/adsorbate system is expressed by the same formula as in the other model, in terms of quantities characterizing the equilibrium gas. An expression is derived for the differential energy, with deformation of the adsorbent taken into account. The two methods of calculating the isosteric heat of adsorption are compared.
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    Nonlinear kinetics of oxygen and nitrogen sorption on carbon molecular sieves (1996)
    Springer
    Journal of porous materials 3 (1996), S. 5-16 
    Details
    ISSN: 1573-4854
    Keywords: carbon molecular sieve ; adsorption ; adsorption kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Equilibrium and kinetics of oxygen and nitrogen sorption in two different carbon molecular sieves (CMS) have been modeled. In both CMS materials, equilibrium characteristics are adequately described by the Langmuir model. However, for kinetics of sorption, one CMS followed classic Fickian diffusion, while the other sample did not. A mathematical model was developed which accurately describes both pure component as well as binary uptakes in both materials. Simple manipulation of the boundary condition of the diffusion process allows the model to accurately predict both Fickian and surface barrier diffusion. All parameters needed to estimate binary uptake rates are obtained from pure component uptakes and isotherms. In addition, the model predicts both pure component and binary diffusion rates with diffusion coefficients which are not concentration dependent.
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    URL: http://dx.doi.org/10.1007/BF01135356
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    Modification of the porosity of pillared clays by carbon deposition. I. Polymer carbonization (1996)
    Springer
    Journal of porous materials 3 (1996), S. 257-266 
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    ISSN: 1573-4854
    Keywords: pillared clay ; pore size modification ; adsorption ; polymers ; carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In order to use pillared clays (PILC) for selective adsorption, further modifications of the porous structure are necessary. The deposition of carbon residues onto the porous structure of pillared clays by the carbonization of polymers (polyvinylalcohol) was proposed to achieve a controlled modification of the pore size. Ti and Al-pillared clays (calcined and non-calcined) were impregnated with PVA (different grades and different concentrations and subsequently carbonized to form carbon phases. The effect of the carbon deposits on the porosity of Ti- and Al-PILC is discussed in terms of pore-blocking, pore-filling and pore-narrowing. The deposition of carbon using PVA resulted in a complete pore-blocking for Al-PILC and in a narrowing of the pore size distribution for Ti-PILC, without achieving a controlled pore-narrowing.
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    URL: http://dx.doi.org/10.1007/BF01137915
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    The Effect of Temperature on the Surface Nature of an Adsorbed Layer of Poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) Block Copolymers (1996)
    Springer
    Pharmaceutical research 13 (1996), S. 1730-1733 
    Details
    ISSN: 1573-904X
    Keywords: poloxamer ; surfactant ; adsorption ; targeting ; surface energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To investigate the influence of the temperature at which adsorption takes place and the temperature at which the adsorbed surface is studied on the polarity of Poloxamer adsorbed to a hydrophobic surface. The implication is that changes in surface nature of adsorbed Poloxamer may subsequently be related to functionality, such as changes in opsonisation of Poloxamer coated latex in animals. Methods. The surface energies of Poloxamer surfactant have been calculated following adsorption to silanised glass plates. The adsorption to the plates was undertaken at a range of concentrations and at different controlled temperatures. The contact angles were measured using three different liquids on each surface, at a range of controlled temperatures. The surface energies were calculated using the harmonic mean and the acid-base models, via Wilhelmy plate contact angle measurements. These data were compared with previously published adsorption and hydrophobic interaction chromatography studies. Results. The apolar surface energy term remained consistent, but the polar contribution (which was totally of the electron donor type) changed depending upon the temperature of adsorption (and to a lesser extent the temperature at which the surface energy was measured). The polar nature was most elevated at the critical micelle concentration/ temperature. The data are consistent with estimates of surface hydrophobicity made using hydrophobic interaction chromatography. Conclusions. It is argued that the changes in surface energy, which result from the different adsorption conditions, can be expected to influence the functionality of the adsorbed coat, especially for application such as drug targeting.
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    URL: http://dx.doi.org/10.1023/A:1016461311635
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    Adsorption of polyacrylic acid on hydrophobic and hydrophilic surfaces (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 548-554 
    Details
    ISSN: 1435-1536
    Keywords: Polyacrylic acid ; γ-Al2O3 ; mercury surface ; adsorption ; voltammetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract In this paper the adsorption of polyacrylic acid (MW=5000) on the hydrophobic mercury surface and on the hydrophilic γ-Al2O3 surface at pH=3–4 in 0.55 M sodium chloride solution was investigated. Measurements of change of the double layer capacitance by phase selective a.c. voltammetry were used for determination of the adsorption of polyacrylic acid on the mercury electrode. The same method was used for the determination of the polyacrylic acid remaining in the solution after the adsorption on hydrophilic particles (γ-Al2O3 particles). The results obtained for adsorption of polyacrylic acid were compared to the results of the adsorption of humic substance of similar molecular weight under similar experimental conditions. The study has shown that polyacrylic acid in acidic solution is strongly adsorbed on the mercury surface, which is comparable to the adsorption of humic substance on the mercury surface. At the same time, the adsorption/deposition of polyacrylic acid on the γ-Al2O3 surface is weaker compared to humic acid, indicating at a smaller degree of interaction of polyacrylic acid with aluminium ions and with hydrophilic surface.
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    URL: http://dx.doi.org/10.1007/BF00655230
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    Sorption of binary liquid mixtures on polymer networks Part I. Determination of surface excess isotherms and free energy functions (1992)
    Springer
    Colloid & polymer science 270 (1992), S. 68-77 
    Details
    ISSN: 1435-1536
    Keywords: Polymers ; adsorption ; networks ; swelling ; macroreticular resins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Two groups of polymer networks (polymer resins) are investigated by selective liquid sorption fromn-propanol-water mixtures. Group 1 consists of gel polymerized polar (hydrophilic) ion exchangers which swell in the binary liquid mixture. Group 2 consists of non-polar, non-swelling, macroporous resins. The free energy isotherms accompanying the sorption processes are calculated from the excess isotherms and the bulk activities. The adsorption excess free energies reveal the differences in polarity of the polymer network.
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    URL: http://dx.doi.org/10.1007/BF00656932
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    Studies of thermally stimulated current in polypropylene/calcium carbonate/surfactant systems (1992)
    Springer
    Colloid & polymer science 270 (1992), S. 113-127 
    Details
    ISSN: 1435-1536
    Keywords: Polypropylene ; filler ; surfactant ; composite ; thermally stimulatedcurrent ; adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thermally stimulated polarization (TSP) and depolarization (TSD) experiments have been performed with two grades of polypropylene and some respective CaCO3-filled composites containing small amounts of nonionic surfactant (0–2 wt%). The effects of electrode blocking, electrode materials on the thermally stimulated currents, and reproducibility of the measurements have been studied. The effect of water vapor adsorbed from the ambient air on the AC dielectric properties and on the thermally stimulated polarization behavior has been determined. The addition of either CaCO3 or surfactant to PP decreases the intensity of the αc depolarization current peak in the pre-melting region, while the presence of both components increases the current. Partial discharges are present in poly propylene/CaCO3 composites under high voltages if neither water vapor nor a coherent surfactant layer is present at the matrix/filler interface. A short literature survey is presented on the TSC studies of polyolefins and their composites, and various mechanisms responsible for the observed changes are discussed, including interfacial polarization, trap redistribution through nucleation, and oriented adsorption.
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    Behavior of pure and mixed DPPC liposomes spread or adsorbed at the air-water interface (1992)
    Springer
    Colloid & polymer science 270 (1992), S. 901-911 
    Details
    ISSN: 1435-1536
    Keywords: Liposomes ; adsorption ; spreading ; surfacefilm ; monolayer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Liposomes from pure dipalmitoylphosphatidylcholine (DPPC) and mixed DPPC: distearoylphosphatidylcholine (DSPC): soybean lecithin (SL) prepared by the Bangham method with sonication were dispersed into solution or spread at the interface and the kinetics of the surface film formation was studied by measuring and recording the evolution of superficial tension, surface potential, and superficial (14C labeled) DPPC density. A simple theoretical approach can describe these kinetics by two processes: irreversible diffusion of closed vesicles into or from the bulk phase, and irrevers ible transformation of closed spherical vesicles into destroyed ones which form the surface film. Diffusion controls the phenomenon for small initial amounts of liposomes. Transformation controls the phenomenon for important initial amounts of liposomes. The kinetic constant of the transformation,K, does not depend on the technique used to form the surface film (spreading or adsorption). The equilibrium and rheological properties of surface films formed after liposome spreading are compared to those of monolayers
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    URL: http://dx.doi.org/10.1007/BF00657735
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    Van der Waals attraction between Stöber silica particles in a binary solvent system (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 779-787 
    Details
    ISSN: 1435-1536
    Keywords: Silica particles ; colloid stability ; Hamaker constant ; van der Waals potential ; adsorption ; rheology ; SAXS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Hydrophilic Stöber silica particles are stable in ethanol, but flocculation may be induced by the addition of sufficient cyclohexane. Low-shear rheological measurements indicated non-Newtonian behaviour beyond the critical cyclohexane concentration. The thickness and composition of the solvation layer around the particles were calculated from the adsorption excess isotherm on the basis of a multilayer adsorption model. The composition dependences of the Hamaker constants of the dispersion medium and the adsorption layer were obtained from optical dispersion measurements. A single-sheet, hard-sphere model predicted a weak van der Waals attraction in the ethanolic regime, but a strong attraction in the cyclohexane-rich region, in good accordance with the rheological properties of the dispersions and visual observations.
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    URL: http://dx.doi.org/10.1007/BF00654674
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    Characterization of solid and dissolved carbon in a spruce-fir Spodosol (1996)
    Springer
    Biogeochemistry 35 (1996), S. 339-365 
    Details
    ISSN: 1573-515X
    Keywords: adsorption ; CP/MAS13C NMR ; DOC ; forest floor leachates ; hydrophilic acids ; hydrophobic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Organic substances are an integral part of the biogeochemistry of many elements in forest ecosystems. However, our understanding of the composition, chemistry, and reactions of these materials are incomplete and sometimes inconsistent. Therefore, we examined in detail dissolved organic carbon (DOC) in forest floor leachates over a two-year period (1992–1993), soil C, and DOC adsorption by a mineral soil to determine the relationship between soil solid and solution C characteristics in a spruce-fir ecosystem. The structural composition of DOC, DOC fractions (hydrophobic and hydrophilic acids, hydrophilic neutrals), and soil samples from the organic and mineral horizons were also analyzed using13C nuclear magnetic resonance (NMR) spectroscopy. Total DOC in forest floor leachates ranged from 7.8 to 13.8 mmol L−1 with an average of 8.6 mmol L−1. Concentrations were highest in September of both 1992 and 1993. Fractionation of the forest floor DOC indicated these solutions contained high organic acid contents that averaged 92% of the total DOC. Hydrophobic acids were also preferentially adsorbed by the B horizon. The13C NMR data suggested alkyl, carbohydrate, aromatic, and carboxylic C were the primary constituents for organic and mineral soils, DOC, and DOC fractions. Compositional changes of C were observed as aromatic and carbohydrate decreased, whereas alkyl, methoxy, and carbonyl moieties increased with depth. However, C composition changed little among the three organic layers based on the similarity of alkyl/carbohydrates ratios as determined from NMR area integration, suggesting that in this acid soil, decomposition proceeds rather slowly. Hydrophobic acids contained high contents of aromatic C, whereas hydrophilic acids were comprised primarily of carboxylic C. Hydrophilic neutrals were rich in carbohydrate C. Results indicated that these DOC fractions were unaltered during the isolation process. Carboxylic C groups appeared to dissolve easily and were probably the primary contributor to organic acidity in our organic dominate leachates. Results also suggested that DOC materials adsorbed on the B horizon underwent further biodegradation. Several seasonal patterns of C composition were observed in the forest floor leachates and DOC fractions collected between 1992 and 1993. Overall, the evidence from this study suggested that (i) DOC levels were mainly controlled by biological activity, (ii) forest floor DOC was comprised primarily of organic acids, (iii) contact of soil leachates with B horizon material affected DOC quantitatively and qualitatively, (iv) phenolic, carboxylic, and carbonyl C appeared to dissolve readily in the forest Oa horizon, (v) DOC materials adsorbed on the B horizon selectively underwent further decomposition, and (vi) C composition is a function of the extent of decomposition and DOC fractions.
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    Displacement processes on hydrophilic/hydrophobic surfaces in methanol-water mixtures (1992)
    Springer
    Colloid & polymer science 270 (1992), S. 1027-1034 
    Details
    ISSN: 1435-1536
    Keywords: Solid liquid interface ; multilayer ; adsorption ; enthalpy of displacement ; layer silicate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The adsorption from methanol/water and the enthalpy of displacement of methanol by water were studied on K-60 silica gel, on graphitized PRINTEX-80, and onn-alkylammonium vermiculites. The adsorption between the hydrophobized silicate layers was followed by x-ray measurements. The excess isotherms of alkylammonium vermiculites in methanol/water exhibit two maxima corresponding to the two steps of the individual isotherm. The equilibrium constant of the exchange of water by methanol is calculated. For calculating the adsorption capacities and molar adsorption potentials, a new equation is proposed which combines the adsorption excess quantities with free energy and enthalpy functions.
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    Adsorption properties of crystalline silicas: (II) Adsorption of anionic surfactants and delamination (1992)
    Springer
    Colloid & polymer science 270 (1992), S. 609-616 
    Details
    ISSN: 1435-1536
    Keywords: Anionic surfactants ; crystalline silicic acids ; delamination ; intercalation ; silica ; surfactant ; adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Lamellar crystalline silicas (crystalline silicic acids, chemical composition SiO2·xH2O; examples: H4Si14O30·xH2O, H4Si20O42·xH2O) are distinguished from the amorphous forms by their layered structure and exceptional adsorption properties. One outstanding example is the reaction with anionic surfactants. Several types of crystalline silicas (typical H4Si20O42·xH2O) can intercalate ionic pairs consisting of surfactant anion and gegen ion into the interlayer space. The saturation value of SDS adsorption is 0.475 mmol SDS/g H4Si20O42·3H2O. The acid H4Si14O30·xH2O adsorbs anionic surfactants at the external surfaces only (saturation value 0.04 mmol/g H4Si14O30·0.8 H2O). When anionic surfactants are adsorbed in the interlayer space, the layer separation increases to such an extent that the crystals disarticulate in a fan-like manner or delaminate into thinner packets of layers or smaller aggregates. Washing-out the SDS ionic pairs or drying reconstitutes the parallel layer orientation and leads to re-aggregation of the packets and fragments.
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    Interaction of sodium dodecylsulfate (SDS) with homoionic montmorillonites: adsorption isotherms and metal-ion release (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 966-973 
    Details
    ISSN: 1435-1536
    Keywords: Sodium dodecylsulfate ; adsorption ; precipitation ; montmorillonite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The interaction of dodecylsulfate anions (DS−) with homoionic Ca-, Mg-, Ni-, Cu-, Cd-, Pb- and Fe-montmorillonites were investigated. Mg- and Cd-montmorillonite do not adsorb DS−, and an anion exchange at the edges of the clay mineral does not take place. Three different adsorption processes are identified on the other montmorillonites: i) Fe-montmorillonite is covered with amorphous iron hydroxide, and DS−-anions are bound at positively charged sites. ii) On Ca- and Pb-montmorillonite DS− is precipitated as Me(DS)2. iii) On Ni- and Cu-montmorillonite DS− forms ion pairs with the cations on the surface. In all cases DS− is not bound above the CMC but the metal ions are mobilized from the surface either by solubilization of the precipitates or by formation of mixed micelles.
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    URL: http://dx.doi.org/10.1007/BF00656626
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    Adsorption behaviors of emulsifiers and biomolecules on temperaturesensitive polymer particles (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 112-116 
    Details
    ISSN: 1435-1536
    Keywords: Temperature-sensitive ; emulsifier ; biomolecules ; adsorption ; surface
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Adsorption and desorption behaviours of emulsifiers and biomolecules on the two kinds of temperature-sensitive composite polymer particles were compared. One (I) was produced by seeded emulsion copolymerization of dimethylaminoethyl methacrylate and ethylene glycol dimethacrylate with 0.17 μm-sized polystyrene seed particles. The other (II) was produced by seeded emulsion copolymerization of N-isopropylacrylamide (NIPAM) and N,N′-methylenebisacrylamide with 0.36 μm-sized styrene-NIPAM copolymer particles. The amount of adsorption at temperatures above each lower critical solution temperature (LCST) was found to be much higher for I than II. In both cases, at temperatures below the LCST, almost all lactalbumin hydrolysate molecules adsorbed above the LCST were desorbed but the desorptions of adsorbed egg albumin and lysozyme molecules were not so high. The adsorption and desorption were reversible for both particles and the efficiency was better for I than II. From these results, it is concluded that the adsorption/desorption of protein onto the temperature-sensitive polymer particles is controllable by changing the temperature below and above the LCST of the shell layer and the sensitivity is based on the surface property of the composite polymer particles.
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    Micropore characterization using the Dubinin-Astakhov equation to analyze high pressure CO2 (273 K) adsorption data (1996)
    Springer
    Journal of porous materials 3 (1996), S. 247-255 
    Details
    ISSN: 1573-4854
    Keywords: adsorption ; micropore characterization ; activated carbon ; Dubinin-Astakhov equation ; Dubinin-Radushkevich equation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The characterization of the pore structure of microporous materials is of interest because of the usefulness of these materials in many applications. Of these, the characterization of carbon adsorbents is particularly problematic because of the presence of small pores with size on the order of small molecules (micropores) along with a wide distribution of pore sizes, and their non-crystalline structure. In this paper, we present results obtained using the Dubinin-Astakhov equation to analyze data from high pressure CO2 adsorption at 273 K to characterize two sets of microporous carbons. Our results support the conclusions of previous workers that the Dubinin-Astakhov (DA) equation is able to linearize adsorption data that gives rise to curved Dubinin-Radushkevich plots. However, when applied over different ranges of relative pressure on the adsorption isotherm, the Dubinin-Astakhov plots result in different values of micropore volume and characteristic adsorption potential. Furthermore, DA analysis of CO2 (273 K) adsorption data over a wide range of pressures (10−3–22000 Tort), gives results different from DA analysis of CO2 (273 K) isotherms measured at low pressures only (10−3–830 Tort). It would appear desirable to apply the DA equation to data that reflects the entire range of micropore filling on the adsorption isotherm, as opposed to data over a limited relative pressure range. For CO2 adsorption at 273 K, this would necessitate adsorption studies at high pressures, to about 28 atm. Micropore volumes obtained in this manner, agreed with the total pore volumes determined by nitrogen (77 K) adsorption for all the activated carbons studied.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01137914
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  • 42
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    Electronic Resource
    Study on non-noble metal catalysts for automotive emission control (1996)
    Springer
    Reaction kinetics and catalysis letters 57 (1996), S. 183-190 
    Details
    ISSN: 1588-2837
    Keywords: Automobile exhaust ; three-way catalyst ; adsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cordierite honeycomb catalysts supported on rare earth (RE)-transition metal oxides, used for removing simultaneously three major pollutants, carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxides (NOx), in automotive emission have been investigated. The results indicate that the catalyst has improved three-way performance (TWP).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02076138
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  • 43
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    Electronic Resource
    Adsorption of Fluorescein Dyes on Albumin Microspheres (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 629-635 
    Details
    ISSN: 1573-904X
    Keywords: bovine albumin ; egg albumin ; microspheres ; adsorption ; hydrophobicity ; fluorescein dyes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The surface characteristics of bovine and egg albumin microspheres were examined using four anionic dyes; sodium fluorescein, eosin, erythrosin, rose bengal, and the cationic dye rhodamine B. The adsorption isotherms of the dyes on unloaded albumin microspheres exhibited Langmuir behavior for dilute solutions of rose bengal, erythrosin, and eosin, suggesting monolayer formation in the initial stages of the sorption process. The adsorption capacity of the microspheres for the dyes (k 2) and the affinity constants of the dyes for the microspheres (k 1) were found to depend on both the polarizability and the hydrophobic properties of the dye, presumably reflecting the heterogeneous character of the microsphere surface. Further, the extent of sorption at higher dye concentrations was found to depend on the ability of the dye to form stable aggregates inside the microspheres and on environmental long-range forces acting at these sites. At both low and high dye concentrations, the amount adsorbed to the microsphere surface increased with increasing hy-drophobicity of the dyes. The lowest adsorption was observed for the nonsubstituted dye fluorescein, whereas the most hydrophobic dye used, rose bengal, was completely adsorbed onto the microsphere surface. The data suggest that the bovine albumin microsphere surfaces are highly hydrophobic and less porous than egg albumin microsphere surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015897909739
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  • 44
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    Electronic Resource
    Apple foliage enhances mating disruption of light-brown apple moth (1996)
    Springer
    Journal of chemical ecology 22 (1996), S. 325-341 
    Details
    ISSN: 1573-1561
    Keywords: Epiphyas postvittana ; Tortricidae ; mating disruption ; pheromone ; apple leaves ; adsorption ; release rate ; electroantennogram ; EAG ; light-brown apple moth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Uptake and release of pheromone and behavioral inhibitor ofEpiphyas postvittanna by apple leaves was tested using field electroantennograms (EAG), trap catches to synthetic lures and virgin females, and chemical analysis. Trap catches in single apple trees (N=3) were monitored for six cycles of six days' duration, using delta traps baited with synthetic pheromone. Polyethylene dispensers (0, 1, 10 per tree) releasing pheromone and inhibitor were present for only the first three days of each cycle. Application of 10 dispensers per tree resulted in complete disruption of trapping, which continued for one day after dispensers were removed. Over the three nights following the removal of the dispensers (days 4–6), trap catch was 0, 10, and 15% of the control catch. In contrast, the presence of only one dispenser per tree led to 0–20% of control catches, but on the three nights following dispenser removal catches were 35, 40, and 80% of the control catch. Field EAGs indicated significantly higher relative pheromone concentrations in the trees with 10 dispensers present, compared to trees with single dispensers, but removal of dispensers produced no detectable treatment effect compared to the control trees one day after dispenser removal. In a second experiment, releases of marked male moths into apple orchard plots following the removal of polyethylene dispensers (1 hr earlier that day) resulted in significantly lower catches in traps baited with virgin females in blocks that had been treated, compared to controls. Recovery of pheromone by solvent washing of leaves loaded with 50 µg of the main component of the sex pheromone (1.26 µg/cm2) was low (2.5%). Leaves held in a pheromone-saturated atmosphere were loaded with 0.045±0.007 µg pheromone/cm2. Analysis of apple leaves taken from a pheromone-treated tree at different distances from the pheromone dispenser showed a decay of the pheromone load per square centimeter with increasing distance from the dispenser, as previously indicated by EAG.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02055102
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