Surface adsorption at low coverage of n-alkanes on bleached kraft papers using gas chromatography

1987 ◽  
Vol 65 (8) ◽  
pp. 1935-1939 ◽  
Author(s):  
N. Gurnagul ◽  
D. G. Gray
Keyword(s):  
Gas Chromatography ◽  
Free Energy ◽  
Surface Coverage ◽  
Surface Adsorption ◽  
Standard Free Energy ◽  
Chromatographic Retention ◽  
Heats Of Adsorption ◽  
Retention Volumes ◽  
Low Coverage ◽  
Entropy Of Adsorption

The adsorption at low surface coverage of a series of n-alkanes on various bleached kraft paper surfaces was measured by gas chromatography. Differences in surface area of the paper samples were readily measured from the gas chromatographic retention volumes. The standard free energy, the enthalpy, and the entropy of adsorption varied linearly with the number of carbon atoms in the n-alkanes. The heats of adsorption were close to the heats of liquefaction, indicating the non-specific interactions of the hydrocarbons with the bleached kraft surfaces. The London component of the surface free energy was estimated from the gas chromatographic results to be 47.9 mN/m.

ADSORPTIVE AND GAS CHROMATOGRAPHIC PROPERTIES OF VARIOUS CATIONIC FORMS OF ZEOLITE X

1964 ◽  
Vol 42 (10) ◽  
pp. 2340-2350 ◽  
Author(s):  
H. W. Habgood
Keyword(s):  
Ionic Radius ◽  
Adsorption Process ◽  
Divalent Cations ◽  
Chromatographic Retention ◽  
Monovalent Cations ◽  
Zeolite X ◽  
Heats Of Adsorption ◽  
Quadrupole Interactions ◽  
Silver Compound ◽  
Retention Volumes

Gas chromatographic retention volumes for O2, N2, CH4, C2H6, C3H8, C4H10, C2H4, and C3H6 have been measured over a range of temperatures between 25 and 400 °C, on columns of the following ion-exchanged forms of zeolite X: Li+, Na+, K+, Mg++, Ca++, Ba++, and Ag+. In addition, for AgX zeolite, full isotherms have been determined for O2, N2, C2H6, and C2H4; and for NaX zeolite, isotherms for C2H6 and C2H4. The gas chromatographic retention volumes agree well with the isotherms in the case of NaX but are significantly low for AgX, presumably as the result of at least a portion of the adsorption process being slow. The heats of adsorption on NaX agree well with literature values for O2, N2, CH4, and C2H6 but are low for C3H8 and C4H10; further indication of slow processes and hence of a limitation of the g.c. technique. The observations can be correlated qualitatively in terms of the interplay of the following effects: (a) cationic field increases with decreasing ionic radius; (b) shielding of smaller cations is greater—at least in the six-membered oxygen-ring sites; (c) divalent cations, while having greater fields, are only half the number of monovalent cations and tend to be found in less exposed sites; and (d) the polarizing power of silver ion, which also occupies all types of exposed sites, is very strong. The most intense interactions were found with AgX; with ethylene a much stronger complex is formed than has been reported for any other silver compound. The significance of molecular quadrupole interactions on these heteroionic surfaces is shown by the much weaker cationic effects observed with O2 (which has negligible quadrupole moment) than with nitrogen.

scholarly journals Studies of adsorption of polychlorocarbons on carbon blacks by gas chromatography

1985 ◽  
Vol 2 (4) ◽  
pp. 219-228 ◽  
Author(s):  
E. V. Zagorevskaya ◽  
N. V. Ishchenko ◽  
A. V. Kiselev ◽  
N. V. Kovaleva
Keyword(s):  
Gas Chromatography ◽  
Carbon Black ◽  
Adsorption Properties ◽  
High Adsorption ◽  
Heats Of Adsorption ◽  
Carbon Blacks ◽  
Before And After ◽  
Retention Volumes ◽  
High Adsorption Capacity ◽  
Airborne Chemicals

Adsorption properties of carbon black before and after modification to polyhalogenohydrocarbons, including polyorganochlorine pesticides, have been investigated. It has been shown that graphitised thermal carbon blacks and carbochroms possess high adsorption capacity relative to the above compounds and can be used as supporting adsorbents to analyse these airborne chemicals. Modification raises the selectivity of adsorbents to the compounds being investigated and lowers retention volumes and heats of adsorption, which makes it possible to carry out thermal desorption of the accumulated species at lower temperatures.

scholarly journals Adsorption Properties and Structure of Some Active Carbons

1993 ◽  
Vol 10 (1-4) ◽  
pp. 211-220 ◽  
Author(s):  
I.A. Bardina ◽  
E.V. Kalashnikova ◽  
N.V. Kovaleva ◽  
T.A. Rudnitskaya ◽  
N.K. Shonya
Keyword(s):  
Gas Chromatography ◽  
Carbon Black ◽  
Active Carbon ◽  
Graphitized Carbon Black ◽  
Adsorption Properties ◽  
Static Method ◽  
Active Carbons ◽  
Heats Of Adsorption ◽  
Graphitized Carbon ◽  
Low Coverage

Gas chromatography has been used to determine the initial low-coverage heats of adsorption of C2–C6 hydrocarbons and their derivatives on active carbon and graphitized carbon black. The porous structure of the active carbon has been determined from the adsorption isotherms of benzene measured at 25°C by a vacuum static method. The isotherms have been analyzed with the help of the BET and Dubinin–Radushkevich theories.

scholarly journals Peptide-Surface Adsorption Free Energy Comparing Solution Conditions Ranging from Low to Medium Salt Concentrations

ChemPhysChem ◽  
2012 ◽  
Vol 13 (17) ◽  
pp. 3782-3785 ◽  
Author(s):  
Yang Wei ◽  
Aby A. Thyparambil ◽  
Robert A. Latour
Keyword(s):  
Free Energy ◽  
Surface Adsorption ◽  
Adsorption Free Energy

Adsorption of Liquids and Swelling of Wood. Part VI. Saturated Amounts and Some Thermodynamic Values of Adsorption

Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 91-97
Author(s):  
Kei Morisato ◽  
Yutaka Ishimaru ◽  
Hiroyuki Urakami
Keyword(s):  
Free Energy ◽  
Standard Free Energy ◽  
Molecular Size ◽  
Free Energy Change ◽  
Energy Change ◽  
Multilayer Adsorption ◽  
Monolayer Adsorption ◽  
Wood Part ◽  
Cohesive Interaction

Summary To understand the swelling phenomenon of wood in liquids,the saturated amount of adsorption of liquids onto wood and the standard free energy changes of the adsorption were determined. The saturated amount of adsorption obtained by regression for several liquids decreased with increasing molecular size of the solvents. The mechanism of wood swelling is discussed systematically taking all the liquids examined in previous experiments into account. Since methanol molecules require more energy for release from cohesive interactions within bulk liquids in the adsorption onto pre-swollen wood,the values of free energy change of adsorption for methanol were lower than the values for acetone,although the relative swelling with methanol was higher. These results suggest that although the cohesive interaction within the bulk liquids reduces adsorptivity,the phenomenon of wood swelling is influenced not only by monolayer adsorption but also by multilayer adsorption. Therefore,the cohesive interaction within the bulk liquids reduces adsorptivity but enhances the condensation which strongly influences the swelling of wood.

scholarly journals The adsorption of vapours on mercury. I. Non-polar substances

1946 ◽  
Vol 187 (1008) ◽  
pp. 53-73 ◽  
Keyword(s):  
Free Energy ◽  
Total Energy ◽  
Langmuir Equation ◽  
Phase Changes ◽  
Two Dimensional ◽  
Surface Phase ◽  
Standard State ◽  
Spreading Pressure ◽  
Benzene Toluene ◽  
Entropy Of Adsorption

Reversible results for the adsorption of benzene, toluene and n -heptane vapours on mercury have been obtained. The films were found to be gaseous and obeyed the Volmer eqution F ( A - b ) = kT , where F = spreading pressure, A =area per molecule and b = co-area. The possibility that the films might be immobile was considered and the Langmuir equation was applied but found unsatisfactory. A standard state for the surface phase was defined and the free energy, total energy and entropy of adsorption evaluated. The heat of adsorption was shown to increase with the amount on the surface. A number of phase changes were found to occur after the completion of monolayer adsorp­tion, the most striking being interpreted as the change over from ‘flat’ to ‘vertical’ adsorp­tion of the toluene molecules. Others were thought to be either two-dimensional condensation or adsorption of a second layer.

The Equilibrium and the Determination of D00 (H—CN)

1975 ◽  
Vol 53 (16) ◽  
pp. 2365-2370 ◽  
Author(s):  
Don Betowski ◽  
Gervase Mackay ◽  
John Payzant ◽  
Diethard Bohme
Keyword(s):  
Free Energy ◽  
Standard Enthalpy ◽  
Transfer Reaction ◽  
Standard Free Energy ◽  
Proton Transfer Reaction ◽  
Enthalpy Change ◽  
Standard Free Energy Change ◽  
Flowing Afterglow ◽  
Standard Enthalpy Change

The rate constants and equilibrium constant for the proton transfer reaction [Formula: see text] have been measured at 296 ± 2 K using the flowing afterglow technique: kforward = (2.9 ± 0.6) × 10−9 cm3molecule−1s−1, kreverse = (1.8 ± 0.4) × 10−10 cm3 molecule1 s−1, and K = 16 ± 2. The measured value of K corresponds to a standard free energy change, ΔG296°, of −1.6 ± 0.1 kcal mol−1 which provides values for the standard enthalpy change, ΔH298°= −1.0 ± 0.2 kcal mol−1, the bond dissociation energy, D00(H—CN) = 124 ± 2 kcal mol−1, and the proton affinity, p.a.(CN−) = 350 ± 1 kcal mol−1.

Standard Free Energy of Adsorption at Liquid Interfaces

1991 ◽  
pp. 277-292 ◽  
Author(s):  
D. K. Chattoraj ◽  
L. N. Ghosh ◽  
P. K. Mahapatra
Keyword(s):  
Free Energy ◽  
Standard Free Energy ◽  
Liquid Interfaces ◽  
Free Energy Of Adsorption
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