REVERSIBILITY IN PHYSICAL ADSORPTION

1955 ◽  
Vol 33 (2) ◽  
pp. 245-250 ◽  
Author(s):  
E. L. Pace ◽  
K. S. Dennis ◽  
S. A. Greene ◽  
E. L. Heric
Keyword(s):  
Heat Capacity ◽  
Adsorption Isotherms ◽  
Physical Adsorption ◽  
Zero Point ◽  
Solid Surfaces ◽  
Heats Of Adsorption ◽  
Calorimetric Measurements ◽  
Adsorbed Phase ◽  
Adsorption Of Gases ◽  
Calorimetric Studies

The question of reversibility and equilibrium is considered in relation to the physical adsorption of gases on finely divided solid surfaces. Conclusions are drawn from calorimetric measurements of (1) adsorption isotherms, (2) integral, differential, and isosteric heats of adsorption, and (3) heat capacity of the adsorbed phase for surface coverages of the order of a monolayer or less. In line with the preceding, results are presented and discussed for calorimetric studies involving (1) heats of adsorption and heat capacities of methane adsorbed on rutile between 80 and 140°K., (2) heats of adsorption of argon on rutile between 60 and 90°K., and (3) the zero point entropy of krypton adsorbed on rutile at a coverage of about 0.57 of the monolayer capacity.

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 A Simple Approach to the 2D Mobile Adsorption of Gases on Heterogeneous Solid Surfaces Exhibiting Random Surface Topography

1989 ◽  
Vol 6 (1) ◽  
pp. 35-51 ◽  
Author(s):  
W. Rudzinski ◽  
J. Jagiello
Keyword(s):  
Surface Topography ◽  
Compressibility Factor ◽  
Simple Approach ◽  
Solid Surfaces ◽  
Random Surface ◽  
Heats Of Adsorption ◽  
Adsorption Of Gases ◽  
Mobile Adsorption ◽  
Simple Equations ◽  
Heterogeneous Solid

Based on a summation to infinity of the virial expansion for the 2D compressibility factor, simple equations have been developed for adsorption isotherms, and heats of adsorption, of 2D dense mobile films adsorbed on solid surfaces. They have subsequently been generalized for the presence of an external, randomly varying potential field, created by the random surface topography exhibited by heterogeneous solid surfaces.

Theoretical Insight of Physical Adsorption for a Single Component Adsorbent+Adsorbate System

2007 ◽  
Author(s):  
Anutosh Chakraborty ◽  
Bidyut Baran Saha ◽  
Shigeru Koyama ◽  
Ibrahim Ibrahim El-Sharkawy ◽  
Kim Choon Ng
Keyword(s):  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Physical Adsorption ◽  
Isosteric Heat ◽  
Single Component ◽  
Actual State ◽  
Adsorbed Phase ◽  
Adsorption Processes ◽  
Classical Thermodynamics

The thermodynamic property surfaces for a single-component adsorbent + adsorbate system have been derived and developed from the view point of classical thermodynamics. These thermodynamic frameworks enable us to compute the specific heat capacity, partial enthalpy and entropy for the analyses of adsorption processes thoroughly. A theoretical framework for the estimation of the isosteric heat of adsorption between an adsorbate (vapor) and an adsorbent (solid) is also derived for the thermodynamic requirements of chemical equilibrium, Maxwell relations and the entropy of the adsorbed phase. Conventionally, the specific heat capacity of the adsorbate is assumed to correspond to its liquid phase specific heat capacity and more recently to that of its gas phase. We have shown here that the derived specific heat capacity fills up the information gap with respect to the state of adsorbed phase to dispel the confusion as to what is the actual state of the adsorbed phase.

THE DISCONTINUITY IN THE ADSORPTION OF GASES, VAPORS, AND LIQUIDS ON SOLID SURFACES AT THE CRITICAL TEMPERATURE UNDER CRITICAL PRESSURE: SYSTEM PROPYLENE-ALUMINA

1933 ◽  
Vol 9 (3) ◽  
pp. 240-251 ◽  
Author(s):  
H. E. Morris ◽  
O. Maass
Keyword(s):  
Critical Temperature ◽  
Liquid State ◽  
Critical Pressure ◽  
Solid Surfaces ◽  
Pressure System ◽  
Gaseous State ◽  
Adsorbed Phase ◽  
Adsorption Processes ◽  
Adsorption Of Gases ◽  
Adsorption Curve

An apparatus and a technique for studying the adsorption of gases, vapors and liquids on solid surfaces are described. The arrangement permits investigations in the region of the critical temperature and the critical pressure. Results with the system propylene and alumina are given. Adsorption from the gas and vapor phases indicates the formation of a surface complex which is unstable at low pressure and high temperature. The density of the adsorbed phase is greater than that of the bulk phase. There is no discontinuity in adsorption processes with a change from vapor state to gaseous state. No evidence was obtained of an increase in critical temperature on the surface of the solid. Adsorption does not occur from the liquid state, and there is a marked discontinuity in the adsorption curve with a change from liquid state to gaseous state. This is probably due to a change in the forces of attraction between liquid molecules and the solid as compared with the attraction between gaseous or vapor molecules and the solid surface. If this is the case it is further evidence for the discontinuity in the region of the critical temperature, which has been previously observed in other experiments in this laboratory.

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