摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v55-020

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

Dielectric data obtained for a variety of adsorbates on porous silica gel and on nonporous rutile are summarized. Four methods of computing the polarizabilities or dielectric constants of the adsorbed matter are outlined and applied using the primary experimental data of capacitance change and volume adsorbed. All four methods contain somewhat arbitrary assumptions and at best are semi-empirical. None predicts values of the electrical constants of the adsorbed species which appear reasonable in all cases. It is concluded that an interpretation of the phenomena revealed by the primary data is not possible until improved methods of computing the polarizability of adsorbed material are developed.

ISSN:0008-4042    

DOI:10.1139/v55-021

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

When the bulk phase of an adsorbent is solid, it has been shown that adsorption often proceeds only to a finite limit as the pressure reaches saturation. A theory is developed for this finite limit, in terms of the excess forces at the surface and the incompatibility of the crystal lattices of the adsorbent and adsorbate. It is applied to the stepwise adsorption of krypton on graphitized carbon black. An extrapolation formula applicable to smooth isotherms at high coverages is developed and shown to be analogous to the Harkins–Jura equation. It is applied to argon adsorbed on carbon black, on xenon preadsorbed on carbon black, on silver iodide, and on anatase. The energies obtained are compared with a theoretical estimate based on the Kirkwood–Müller equation. A theory for calculating isotherms on preadsorbed layers is developed and compared with the data for argon on xenon.

ISSN:0008-4042    

DOI:10.1139/v55-022

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

The theory presented in this paper permits the determination of extremal bounds for a given adsorbate–adsorbent system within which the adsorption isotherms must fall if certain assumptions pertaining to the nature of the adsorption process are applicable. The use of interpolation theory in estimating lower and upper bounds on physical quantities of interest in adsorption theory is also discussed.

ISSN:0008-4042    

DOI:10.1139/v55-023

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

The flow of water through the micropore system of activated carbon has been described in previous papers as a hydrodynamic flow of liquid water under high pressure gradients due to surface forces. It is shown below that these high pressures are probably real and that the temperature coefficient of the flow rate is closely related to the temperature coefficient of the viscosity of liquid water. Surface tension is discussed.

ISSN:0008-4042    

DOI:10.1139/v55-024

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

Theoretical isotherms have been developed which when compared to experimental isotherms showing hysteresis, allow the calculation of pore size, pore size distribution, and surface area of the sorbent. Interpretation of some experimental isotherms obtained with porous vycor glass shows that this system can best be represented by the "ink bottle" pore model with a Gaussian distribution of pore sizes. The mean pore radius of the porous glass is about two thirds of the Kelvin radius, and the surface area greater than that obtained from the B.E.T. theory. The Kelvin radius is interpreted as a weighted average, but the B.E.T. surface area appears more fundamentally different.

ISSN:0008-4042    

DOI:10.1139/v55-025

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

Previous theoretical calculations and experimental measurements of the surface energies or enthalpies of the alkali halides are reviewed briefly. A new attempt to determine the surface enthalpy associated with the {100} face of sodium chloride from a calorimetric study of the effect of particle size on the heat of solution is described. The result (305 ergs/cm.2at 25 °C.) appears to be larger than might be predicted on the basis of the classical Born-Mayer theory.

ISSN:0008-4042    

DOI:10.1139/v55-026

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

An effect of particle size upon the heat capacity of sodium chloride has been found in the temperature range 9° to 21°K. The experiments were done with three NaCl samples of specific surfaces between 38 and 59 sq. meters per gm. The observed effect has the temperature dependence predicted by theory but its magnitude is three to four times larger than expected. It is unlikely that adsorbed gases have made any significant contribution in the experiments. The accuracy with which the specific heat and surface area differences have been determined is not high enough to show definitely whether or not the surface specific heat is an extensive property of the surface.

ISSN:0008-4042    

DOI:10.1139/v55-027

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

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.

ISSN:0008-4042    

DOI:10.1139/v55-028

出版商:NRC Research Press    

年代:1955

数据来源: NRC

摘要:

The heats of immersion of rutile in a series of short chain organic liquids are found experimentally to be an approximate linear function of the dipole moment of the wetting liquid. The significance of the relation is discussed in terms of the polar van der Waals force contribution which is primarily dependent on dipole moment. The average distance of approach of a dipole to the rutile surface and the effective surface force field extending from the rutile surface are calculated.The net adsorption energy, which is calculated directly from heat of immersion data, is related to the energy contributions resulting from the various polar and nonpolar van der Waals forces active in the adsorption process: These energy contributions which make up the total adsorption energy are calculated for the interaction of an alcohol and a hydrocarbon with both a heteropolar (rutile) and a homopolar (Graphon) surface. On the basis of the results obtained, the effects of chain length and functionality of the liquids on the heat of immersion are discussed.

ISSN:0008-4042    

DOI:10.1139/v55-029

出版商:NRC Research Press    

年代:1955

数据来源: NRC