Physical Adsorption on Uniform Surfaces

Champion, Wyatt M.; Halsey, G. D.

doi:10.1021/j150508a009

Cited by 57 publications

(12 citation statements)

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“…Very often, such steps or plateaus are not observed (Champion and Halsey, 1953) due to non-uniform and cooperative adsorption (Halsey, 1948). On a plane uniform surface, adsorption would proceed in a stepwise fashion as pressure increases (Champion and Halsey, 1953).…”

Section: Discussionmentioning

confidence: 99%

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Enthalpy of water adsorption and surface enthalpy of lepidocrocite (γ-FeOOH)

Majzlan

Mazeina

Navrotsky

2007

Geochimica et Cosmochimica Acta

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Section: Discussionmentioning

confidence: 99%

“…On a plane uniform surface, adsorption would proceed in a stepwise fashion as pressure increases (Champion and Halsey, 1953). A plateau observed during the hydration of the lepidocrocite surface might mean that this phase possesses such plane(s).…”

Section: Discussionmentioning

confidence: 99%

Enthalpy of water adsorption and surface enthalpy of lepidocrocite (γ-FeOOH)

Majzlan

Mazeina

Navrotsky

2007

Geochimica et Cosmochimica Acta

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“…Since w is approximately equal to one half the energy of sublimation of the bulk crystal, and since g,, will always be near unity, calculations using equation [:I. ] will lead to a completely stepwise isotherm (1). In order to find the positions of the risers of the steps in terms of #/PO, the value one half is given to O,,, unity to 0, , -1, and zero to This yields a simpIe expression for the pressure a t the nth step:…”

Section: A Theory Predicting a Finite Adsorption Limitmentioning

confidence: 99%

“…This equation can be put into usable form by making two assumptions; first that the energy En is given by the cube law (1,6) …”

Section: A Theory Predicting a Finite Adsorption Limitmentioning

confidence: 99%

The Growth of Crystalline Layers on Foreign Surfaces

Singleton¹,

Halsey²

1955

Can. J. Chem.

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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 a t the surface and the incompatibility of the crystal lattices of the adsorbent and adsorbate. I t is applied to the stepwise adsorption of krypton on graphitized carbon black. An extrapolation formula applicable to smooth isotherms a t high coverages is developed and shown to be analogous to the Harkins-Jura equation. I t is applied to argon adsorbed on carbon black, on xenon preadsorbed on carbon black, on silver iodide, and on anatase. Theenergiesobtained are compared with a theoretical estimate based on the ICirkwood-Miiller equation. A theory for calculating isotherms on preadsorbed layers is developed and compared with the data for argo11 on xenon.

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“…Champion and Halsey (8) have predicted step-wise isotherms on homogeneous surfaces on theoretical grounds. They made use of Hill's isotherm equations (14) modified so as to include the influence of the surface force field of the adsorbent up to the nth layer.…”

Section: Introductionmentioning

confidence: 99%

Heats of Adsorption of Krypton on Highly Graphitized Carbon Black

Beebe¹,

Amberg²,

Spencer³

1955

Can. J. Chem.

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Calorimetric heats have been determined a t -183'C. for the adsorption of krypton on a highly graphitized sample of carbon black. This adsorption system is of particular interest because of the extreme step-wise nature of the isotherm. Both the heat-coverage curve and the isotherm appear to be indicative of a high degree of homogeneity of the adsorbing surface. INTRODUCTIONGraphitized carbon blacks are among the very few known solid adsorbents which appear to exhibit energetically homogeneous adsorbing surfaces. Schaeffer, Smith, and Polley (21) have described the preparation of a number of these blacks. These authors (19) found a development of steps in the argon isotherms a t -195'C. on carbon blacks heat treated a t successively higher temperatures up to 3000°C. (notably the 'Spheron 6' and 'P-33' series), which they interpreted as indicative of increasing homogeneity of the surface.Steps were also observed with oxygen and to a lesser extent with nitrogen a s the adsorbate. Champion and Halsey (8) have predicted step-wise isotherms on homogeneous surfaces on theoretical grounds. They made use of Hill's isotherm equations (14) modified so as to include the influence of the surface force field of the adsorbent up to the nth layer. Conversely, they have shown that the smoothing out of such steps on a homogeneous surface requires untenable assumptions, and they have therefore concluded that the more coinmon smooth type of isotherm must be due to surface heterogeneity.A number of publications froin this laboratory concerning chiefly the adsorption of nitrogen and argon on carbon surfaces show evidence of a maximunl value in the heat-coverage curve a t the monolayer (3, 6, 7). The evolution of what is thought to be a homogeneous surface is particularly well demonstrated by the adsorption of argon on a series of Spheron blacks (7). With heat treatment to increasingly higher temperatures causing both the removal of oxygen and also increasing graphitization, the initial high section of the heatcoverage curve is gradually both lowered and flattened out, whilst the rise due to lateral interaction between the adsorbed molecules thus becomes more clearly delineated and the maximum value a t the monolayer shows a slight increase. This behavior is reflected in the second layer, but to a lesser extent, probably because adsorption into separate layers is less pronounced a t that stage.'11Canl~scr ipt received Septelllber 16, 1954.

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Physical Adsorption on Uniform Surfaces

Cited by 57 publications

References 0 publications

Enthalpy of water adsorption and surface enthalpy of lepidocrocite (γ-FeOOH)

Enthalpy of water adsorption and surface enthalpy of lepidocrocite (γ-FeOOH)

The Growth of Crystalline Layers on Foreign Surfaces

Heats of Adsorption of Krypton on Highly Graphitized Carbon Black

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