Heterogeneity effects in the multilayer adsorption of gases on solid surfaces

1978 ◽  
Vol 54 (3) ◽  
pp. L1-L4 ◽  
Author(s):  
M. Jaroniec ◽  
M. Borówko ◽  
J.K. Garbacz
Keyword(s):  
Solid Surfaces ◽  
Multilayer Adsorption ◽  
Adsorption Of Gases ◽  
Heterogeneity Effects

Multilayer Adsorption of Gases on Heterogeneous Solid Surfaces

1975 ◽  
Vol 256O (1) ◽  
Author(s):  
W. Rudziński ◽  
S. Sokolowski ◽  
M. Jaroniec ◽  
J. Tóth
Keyword(s):  
Solid Surfaces ◽  
Multilayer Adsorption ◽  
Adsorption Of Gases ◽  
Heterogeneous Solid

scholarly journals Pickett Equation for the Description of Adsorption on Arbitrary Surfaces

2020 ◽  
Vol 4 (2) ◽  
pp. 17
Author(s):  
Volodymyr V. Kutarov ◽  
Eva Schieferstein ◽  
Shanath A. A. Jayaweera
Keyword(s):  
Fractal Dimension ◽  
Water Vapor ◽  
Coal Sample ◽  
Lunar Regolith ◽  
Theoretical Models ◽  
Multilayer Adsorption ◽  
Topological Approach ◽  
Adsorption Of Water ◽  
Adsorption Of Gases ◽  
Adsorption Of Water Vapor

The theory of multilayer adsorption of gases, namely the Pickett equation, has been developed to the case of adsorption on arbitrary surfaces in a molecular and a topological approach. We present the prediction of the fractal dimension for the surface of an adsorbent and for the set of interfaces generated by the growing of layers. The theoretical models correctly predict quantities and qualitative features of the experiment for two systems: adsorption of water vapor (T = 298 K) on the sample of lunar regolith and of nitrogen (T = 77 K) on a coal sample.

On the Hysteresis of Adsorption on Solid Surfaces

1952 ◽  
Vol 5 (2) ◽  
pp. 288
Author(s):  
RG Wylie
Keyword(s):  
Phase Transitions ◽  
Solid Surface ◽  
Three Dimensional ◽  
Solid Surfaces ◽  
Two Dimensional ◽  
Capillary Effects ◽  
First Order ◽  
Adsorption Of Gases ◽  
First Order Phase ◽  
Hysteresis Phenomena

Hysteresis phenomena associated with the adsorption of gases on solid surfaces are usually explained in terms of three-dimensional capillary effects or with more or less unspecific reference to phase transitions. It is shown that hysteresis effects are to be expected when two dimensional phase transitions occur on solids. In the connection, the thermodynamic equation governing the equilibrium of small, incompressible two-dimensional phases is derived. Such phases can form on an imperfect solid surface in an irreversible manner and, as calculation shows, can contribute significantly to the hysteresis of adsorption. In some cases the phase change may be responsible for the whole effect. The diffuseness of first-order phase transitions may be due to the same mechanism.

Physical properties of surfaces I - Kinetic friction

1935 ◽  
Vol 234 (741) ◽  
pp. 329-354 ◽  
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Surface Effect ◽  
Physical And Mechanical Properties ◽  
Surface Force ◽  
Solid Surfaces ◽  
Dust Particles ◽  
Kinetic Friction ◽  
Adsorption Of Gases ◽  
Molecular Layers

These papers describe an investigation of the physical and mechanical properties of solid surfaces, and the effect which the surfaces have on matter in their immediate vicinity. It is well known that the properties of gases, liquids and crystallizing solids are profoundly modified in the neighbourhood of a surface. There is, however, some uncertainty as to the magnitude and range of action of this surface force. Most experiments on the adsorption of gases show that the effect is confined to one or two molecular layers at the interface while in the case of liquid crystals we know that the surface effect can extend beyond this and causes an orientation of the crystal aggregates to a distance of several thousand Angstroms. Some workers have claimed that films of air or of alcohol ca . 40,000 A thick apparently possessed sufficient rigidity to resist a steady pressure equal to several grammes weight. It has been shown, J however, that if the surfaces are carefully polished and are free from dust particles there is no evidence for a long range surface effect of this magnitude.

Fractal bet and FHH theories of adsorption: a comparative study

1989 ◽  
Vol 423 (1864) ◽  
pp. 169-188 ◽  
Keyword(s):  
Critical Evaluation ◽  
Power Laws ◽  
Wall Effects ◽  
Topological Dimension ◽  
Multilayer Adsorption ◽  
High Coverage ◽  
Adsorbed Phase ◽  
Bet Isotherm ◽  
Adsorption Of Gases ◽  
Bet Theory

Two theories of multilayer adsorption of gases, namely the BrunauerEmmett-Teller (bet) theory and the Frenkel-Halsey-Hill (fhh) theory, have recently been extended to the case of fractal substrates in a number of different ways. We present a critical evaluation of the various predictions. The principal results are the following. At high coverage, the fractal bet and fhh isotherms apply to mass and surface fractals, respectively. Both give characteristic power laws with D -dependent exponents ( D = fractal dimension of the substrate). The bet isotherm additionally depends on the topological dimension D top of the substrate. For fractal aggregates ( D top = 1) with D < 2, the adsorbed phase exists only in a highly disordered state. The bet theory is sensitive to multiple-wall effects (they affect prefactors); the fhh theory is not. For the fhh theory, detailed assessments of the approximations in the model are available. The predictions of the fhh theory have been observed on fractal silver surfaces.

Adsorption of Dopamine-hydrochloride (DPH) from Aqueous Solution

1970 ◽  
Vol 3 (1) ◽  
Author(s):  
ME Quayum ◽  
RJ Mannan ◽  
Syed Golam Rahman
Keyword(s):  
Aqueous Solution ◽  
Adsorption Isotherm ◽  
Linear Trend ◽  
Solid Surfaces ◽  
Multilayer Adsorption ◽  
Initial Concentration ◽  
Ph Values ◽  
Systematic Pattern ◽  
Dopamine Hydrochloride ◽  
Adsorption Phenomena

Adsorption of dopamine hydrochloride 3-hydroxy tyraminium chloride on solid surfaces like silica gel, alumina, kaolin and attapulgite from aqueous solution under different pH values were studied. It was observed that the extent of adsorption of dopamine hydrochloride (DPH) with various pH values did not show any systematic pattern for all the four solids. In most cases it was found that pH has little influence on the extent of adsorption even though adsorption increased with increasing initial concentration of the adsorbate solution. The Langmuir plots in most cases showed non-linear trend indicating multilayer adsorption. Adsorption of DPH on all four solids was consistent with the Frendlich adsorption isotherm and thus it is evident that the multilayer adsorption takes place from solutions. The adsorption phenomena were kinetically found to be ideal and it is confirmed from the experimental results that DPH does not interact with any of the four solids. The adsorption phenomena were investigated with respect to change in concentration, temperatures and duration of the process. Key words: Adsorption, DPH, Monolayer and multilayer, pH and concentration varieties. Dhaka Univ. J. Pharm. Sci. Vol.3(1-2) 2004 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

Sign in / Sign up

Export Citation Format

Share Document