A NEW METHOD FOR FINDING HETEROGENEOUS ENERGY DISTRIBUTIONS FROM PHYSICAL ADSORPTION ISOTHERMS

1965 ◽  
Vol 43 (11) ◽  
pp. 1934-1940 ◽  
Author(s):  
J. P. Hobson
Keyword(s):  
Experimental Data ◽  
Adsorption Isotherms ◽  
Physical Adsorption ◽  
Heterogeneous Surface ◽  
New Method ◽  
Energy Distributions ◽  
Adsorption Energies ◽  
Step Type

A model is described which assumes that a heterogeneous surface has a distribution of adsorption energies ƒ(E) for physical adsorption. A new solution is presented giving ƒ(E) for a number of step-type local isotherms, which are chosen to represent varying degrees of adsorbate–adsorbate interaction. The solution permits ƒ(E) to be obtained quite simply from isotherm data at one temperature. This solution for ƒ(E) may then be used to calculate isotherms at other temperatures. The latter isotherms represent predictions of the model and may be compared with experimental data.

ANALYSIS OF PHYSICAL ADSORPTION ISOTHERMS ON HETEROGENEOUS SURFACES AT VERY LOW PRESSURES

1965 ◽  
Vol 43 (11) ◽  
pp. 1941-1950 ◽  
Author(s):  
J. P. Hobson
Keyword(s):  
Experimental Data ◽  
Excellent Agreement ◽  
Adsorption Isotherms ◽  
Pressure Range ◽  
Physical Adsorption ◽  
Maximum Energy ◽  
Heterogeneous Surfaces ◽  
Energy Distributions ◽  
Vacuum Apparatus ◽  
Low Pressures

A method previously described for finding heterogeneous energy distributions ƒ(E) from physical adsorption isotherms is applied to experimental data for argon, nitrogen, and helium obtained in an ultrahigh vacuum apparatus in the pressure range [Formula: see text] Torr. The adsorbent was Pyrex and matching temperatures were 77.4, 90.2, and 4.2 °K for the three gases respectively. ƒ(E) was found to be asymmetric about a maximum energy whose location depended critically upon the magnitude of assumed adsorbate–adsorbate interaction (Q). However, the isotherms calculated at temperatures other than the matching temperature were insensitive to Q, and hence to the detailed form of the local isotherm. These calculated isotherms showed excellent agreement, not only with the data on Pyrex, but also with the data of several workers using various adsorbents and temperatures. The latter result suggests a similar adsorbing surface for all these adsorbents.

INFLUENCE OF GEOMETRIC AND ENERGETIC HETEROGENEITY ON ADSORPTION ISOTHERMS

Fractals ◽  
1995 ◽  
Vol 03 (02) ◽  
pp. 235-250 ◽  
Author(s):  
MASSIMILIANO GIONA ◽  
MANUELA GIUSTINIANI ◽  
DOUGLAS K. LUDLOW
Keyword(s):  
Experimental Data ◽  
Simple Model ◽  
Adsorption Isotherms ◽  
Energy Landscape ◽  
Adsorption Equilibria ◽  
Preferential Adsorption ◽  
Consistent Model ◽  
Energetic Heterogeneity ◽  
Adsorption Energies ◽  
Effect Of Surface

The relationships between geometric roughness and energetic heterogeneity are discussed by considering a thermodynamically consistent model of adsorption isotherms (Keller model) which encompasses fractal scaling and the dependence of the adsorption energies on the coverage. Experimental results validate this model and indicate that it can be used not only to interpolate experimental data but also to predict adsorption equilibria of multicomponent rnixtures. The peculiar non-Henry behaviour of the Keller model at low pressure is discussed by considering a simple model of preferential adsorption on a rough energy landscape and including the effect of surface diffusion.

scholarly journals Argon and Nitrogen Physical Adsorption on Boron Nitride

1987 ◽  
Vol 4 (1-2) ◽  
pp. 121-130 ◽  
Author(s):  
E.J. Bottani ◽  
J.R. Zarate ◽  
L.E. Torre Cascarini De
Keyword(s):  
Phase Transition ◽  
Distribution Function ◽  
Boron Nitride ◽  
Adsorption Isotherms ◽  
Physical Adsorption ◽  
Experimental Conditions ◽  
Cross Sectional ◽  
Adsorbed Phase ◽  
Isotherm Adsorption ◽  
Adsorption Energies

Physical adsorption isotherms of N2 and Ar on boron nitride are analysed and the behaviour of the adsorbed phase is discussed. Different models are used to interpret the adsorbed states. The behaviour of the BET C parameter suggests that a phase-transition occurs in Ar adsorption which is not showed in its isotherm. Adsorption energies distribution functins are calculated using a double Gaussian as distribution function. Nitrogen cross-sectional areas, under experimental conditions are estimated respect to those of the Ar.

scholarly journals Adsorption Equilibrium of 1, 1-Dichloro-1-fluoroethane (HCFC-141b) on a Hydrophobic Zeolite

1998 ◽  
Vol 16 (2) ◽  
pp. 67-75 ◽  
Author(s):  
Wen-Tien Tsai ◽  
Ching-Yuan Chang ◽  
Chih-Yin Ho
Keyword(s):  
Experimental Data ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Adsorption Isotherms ◽  
Ozone Depletion ◽  
Adsorption Equilibrium ◽  
Stratospheric Ozone ◽  
Stratospheric Ozone Depletion ◽  
Equilibrium Isotherms ◽  
Entropy Of Adsorption

Of the major replacements for chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) are now accepted as being prime contributors to stratospheric ozone depletion. As a consequence, the development of adsorbents capable of adsorbing and recovering specific HCFCs has received great attention. This paper describes an investigation of the adsorption equilibrium of 1, 1-dichloro-1-fluoroethane (HCFC-141b) vapour on a commercial hydrophobic zeolite. The corresponding Henry, Freundlich and Dubinin–Radushkevich (D–R) equilibrium isotherms have been determined and found to correlate well with the experimental data. Based on the Henry adsorption isotherms obtained at 283, 303 and 313 K. thermodynamic properties such as the enthalpy, free energy and entropy of adsorption have been computed for the adsorption of HCFC-141b vapour on the adsorbent. The results obtained could be useful in the application of HCFC adsorption on the hydrophobic zeolite studied.

Real-Time Prediction Method for Performance Degradation Trend Based on Reliability Experimental Data

2013 ◽  
Vol 321-324 ◽  
pp. 757-761 ◽  
Author(s):  
Chen Liang Song ◽  
Zhen Liu ◽  
Bin Long ◽  
Cheng Lin Yang
Keyword(s):  
Experimental Data ◽  
Real Time ◽  
Field Data ◽  
Prediction Method ◽  
Field Method ◽  
Performance Degradation ◽  
New Method ◽  
Time Prediction ◽  
Prediction Result ◽  
The Relationship

According to the real-time prediction for performance degradation trend, the commonly used method is just based on field data. But this methods prediction result will not be so much ideal when the fitting of degradation trend of field data is not good. To solve the problem, the paper introduces a new method which is not only based on field method but also based on reliability experimental data coming from the history experiment. We use the relationship between the field data and reliability experimental data to get the result of the two kinds of data respectively and then get the weights according to the two prediction results. Finally, the final real-time prediction result for performance degradation tendency can obtain by allocating the weights to the two prediction results.

A New Method to Assess Ductility of CFT Box Columns with Binding Bars under Axial Compression

2012 ◽  
Vol 446-449 ◽  
pp. 78-81 ◽  
Author(s):  
Yue Ling Long ◽  
Jian Cai
Keyword(s):  
Experimental Data ◽  
Axial Compression ◽  
Material Properties ◽  
New Method ◽  
Box Columns ◽  
Good Agreement

A new method based on material properties instead of experimental data was proposed to assess the ductility of concrete-filled steel box columns with binding bars and those without binding bars. Comparison between ductility coefficients based on experimental data and the calculated values by the proposed method shows good agreement.

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