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.

BET Adsorption Isotherm and Surface Heterogeneity

1992 ◽  
Vol 57 (6) ◽  
pp. 1201-1209
Author(s):  
Lydia Ethel Cascarini de Torre ◽  
Eduardo Jorge Bottani
Keyword(s):  
Distribution Function ◽  
Adsorption Isotherm ◽  
Statistical Mechanics ◽  
Adsorption Isotherms ◽  
Surface Heterogeneity ◽  
Adsorption Energies ◽  
Multilayer Formation ◽  
Effect Of Surface

The BET adsorption isotherm is modified in order to take account of surface heterogeneity. The adsorption isotherm is obtained following the statistical mechanics formalism, proposed by Steele, and the effect of surface heterogeneity is limited to the first layer. A Gaussian adsorption energies distribution function is used to describe surface heterogeneity. The variations of the C parameter, multilayer formation and the inversion of adsorption isotherms are analysed.

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.

scholarly journals Application of the DR and DS Equations to Benzene Adsorption from Water Solutions

1993 ◽  
Vol 10 (1-4) ◽  
pp. 203-209 ◽  
Author(s):  
N.A. Eltekova ◽  
Yu.A. Eltekov
Keyword(s):  
Experimental Data ◽  
Adsorption Isotherms ◽  
Activated Carbons ◽  
Microporous Carbon ◽  
Benzene Adsorption ◽  
Adsorption Behaviour ◽  
Experimental Adsorption ◽  
Water Solutions ◽  
Adsorption Equilibria ◽  
Micropore Filling

Equations of the theory of micropore filling have been applied to the description of adsorption equilibria in systems containing microporous carbon and benzene solutions in water. The parameters of these equations have been evaluated from experimental data obtained for two commercial activated carbons. Comparison of the calculated and experimental adsorption isotherms suggest that these activated carbons are characterized by heterogeneous microporosity. The effect of water on the adsorption behaviour of benzene molecules in the micropores has been considered.

The Tensile Property of the SPF/Cotton Blended Yarn

2011 ◽  
Vol 321 ◽  
pp. 192-195
Author(s):  
Qing Bin Yang ◽  
Xiao Yang
Keyword(s):  
Experimental Data ◽  
Simple Model ◽  
Tensile Property ◽  
Cotton Fibers ◽  
Blended Yarn ◽  
The Difference ◽  
The Relationship

In order to analysis the relationship between the strength and elongation and the blended ratio of SPF/Cotton blended yarn, the strength and elongation of SPF /cotton blended yarn with different blended ratio were measured and compared with the simple model. The results indicated that For the SPF/cotton blended yarn, the difference between the experimental data and the model value is remarkable because of the high cohesion of the cotton fibers.

scholarly journals Isotopic fractionation during grain coarsening of wet snow

1993 ◽  
Vol 18 ◽  
pp. 129-134 ◽  
Author(s):  
Masayoshi Nakawo ◽  
Shigeru Chiba ◽  
Hiroshi Satake ◽  
Shigeru Kinouchi
Keyword(s):  
Experimental Data ◽  
Simple Model ◽  
Rapid Change ◽  
Isotopic Fractionation ◽  
Water Interface ◽  
Grain Coarsening ◽  
Isotope Concentration ◽  
Large Particles ◽  
Wet Snow ◽  
Ice Water

Isotopic composition of solid and liquid portions of wet snow was investigated experimentally. The compositions changed with time, δ values of ice becoming heavier than those for water. A simple model was proposed to explain their temporal variation. It predicted, however, a more rapid change of δ values than the trend obtained in the experiments. This suggests the presence of a “diffusion layer” adjacent to growing snow particles, where isotope concentration has dropped at the ice-water interface because of the fractionation during grain coarsening. The slope in δD–δ18O diagram estimated by the model is compatible with the experimental data. It is considered, therefore, that the freezing fraction, the part of the liquid which refreezes to relatively large particles during grain coarsening, could be estimated by measuring the isotope concentration.

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.

A SIMPLE MODEL FOR ORIENTATIONAL ORDERING OF A SILVER MONOLAYER ELECTRODEPOSITED ON A C(0001) SURFACE

1995 ◽  
Vol 02 (04) ◽  
pp. 489-494 ◽  
Author(s):  
E.E. MOLA ◽  
A.G. APPIGNANESSI ◽  
J.L. VICENTE ◽  
L. VAZQUEZ ◽  
R.C. SALVAREZZA ◽  
...  
Keyword(s):  
Experimental Data ◽  
Fourier Series ◽  
Simple Model ◽  
Series Expansion ◽  
Unit Cell ◽  
Fourier Series Expansion ◽  
Crystal Formation ◽  
Substrate Potential ◽  
Weber Type ◽  
Orientational Ordering

The model for the angular orientational energy (AOE) has been extended to hexagonal submonolayer domains of Ag electrodeposited at a constant overpotential on a C(0001) surface. These domains which are characterized by an epitaxy angle θ=15±5° and an Ag−Ag distance d Ag−Ag =0.330± 0.016 nm, can be considered as precursors of 3D Ag crystal formation, according to a Volmer-Weber type mechanism. Calculations are based upon a simple Hamiltonian evaluated by introducing the concept of the commensurable unit cell. A Fourier series expansion for the substrate potential was used. Results from the model predict the existence of a commensurable cell in agreement with the experimental data derived from STM imaging.

scholarly journals Estimate of Glacier Ablation under a Debris Layer from Surface Temperature and Meteorological Variables

1982 ◽  
Vol 28 (98) ◽  
pp. 29-34 ◽  
Author(s):  
M. Nakawo ◽  
G.J. Young
Keyword(s):  
Experimental Data ◽  
Simple Model ◽  
Surface Temperature ◽  
Temperature Data ◽  
Meteorological Variables ◽  
Glacier Ablation ◽  
Surface Temperature Data ◽  
Good Agreement

AbstractA simple model suggests that the ablation under a debris layer could be estimated from meteorological variables if the surface temperature data of the layer are available. This method was tested by analyzing the data obtained from experiments with artificial debris layers. Fairly good agreement was obtained between the estimated and the experimental data.

PHOTOEMISSION CALCULATION WITH A SIMPLE MODEL FOR THE PHOTON FIELD: APPLICATION TO ALUMINIUM

1991 ◽  
Vol 05 (01) ◽  
pp. 65-72 ◽  
Author(s):  
P. DAS ◽  
R.K. THAPA ◽  
N. KAR
Keyword(s):  
Experimental Data ◽  
Simple Model ◽  
Fermi Level ◽  
Dielectric Function ◽  
Cross Sections ◽  
Free Electron ◽  
Surface Region ◽  
Field Application ◽  
Frequency Dependent ◽  
Photon Field

Photoemission cross-sections are calculated, using a simple “local” dielectric function for computing the photon field in the surface region and free electron wavefunctions. Comparisons are made with the experimental data for the frequency-dependent normal photoemission from the Fermi level of aluminium, and the importance of the variation of the photon field in the surface region is pointed out.

Sign in / Sign up

Export Citation Format

Share Document