Calculation of Thermodynamic Functions of Adsorbed Molecules from Adsorption Isotherm Measurements: Nitrogen on Graphon<sup>1,2</sup>

Hill, Terrell L.; Emmett, P. H.; Joyner, Leslie G.

doi:10.1021/ja01155a026

Cited by 114 publications

(28 citation statements)

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“…In the sub-monolayer region (surface densities less than 11µmol/m 2 ), the entropy decreases as the number of available configurations for monolayer molecules decreases, then increases again as molecules adsorb beyond a monolayer distance from the surface, and finally approaches the molar entropy of liquid-like argon as higher layers are built up. This confirms an earlier conclusion [18] that adsorbed argon approaches the liquid state as adsorption increases, and shows that this state is reached in this system when approximately two statistical monolayers have been adsorbed. …”

Section: Average Duration Per Configurationsupporting

confidence: 91%

Chemical potential, Helmholtz free energy and entropy of argon with kinetic Monte Carlo simulation

Fan

Nicholson

et al. 2013

Molecular Physics

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We present a method, based on kinetic Monte Carlo (kMC), to determine the chemical potential, Helmholtz free energy and entropy of a fluid within the course of a simulation. The procedure requires no recourse to auxiliary methods to determine the chemical potential, such as the implementation of a Widom scheme in Metropolis Monte Carlo simulations, as it is determined within the course of the simulation. The equation for chemical potential is proved, for the first time in the literature, to have a direct connection with the inverse Widom potential theory in using the real molecules, rather than the ghost molecules. We illustrate this new procedure by several examples, including: fluid argon and adsorption of argon as a non-uniform fluid on a graphite surface and in slit pores.

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Section: Average Duration Per Configurationsupporting

confidence: 91%

Chemical potential, Helmholtz free energy and entropy of argon with kinetic Monte Carlo simulation

Fan

Nicholson

et al. 2013

Molecular Physics

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“…The entropy-coverage curves follow the characteristic pattern found, for instance, by Hill, Emmett, and Joyner for the system nitrogen-Graphon (15). Crossing of the two curves takes place a t the monolayer, where there is a minimum in the integral entropy curve.…”

Section: Resultssupporting

confidence: 75%

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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“…The integral entropy can be qualitatively interpreted as the order-disorder of the adsorbed molecules. In accordance with Hill et al (1951), the minimum integral entropy can be interpreted as the required moisture content for forming a monolayer because a monolayer corresponds to a small number of configurations in the system. This minimum will occur when strong bonds between the adsorbate (water) and adsorbent (food) are formed (Nunes and Rotstein, 1991).…”

Section: Thermodynamic Propertiesmentioning

confidence: 98%

“…Gregg and Sing (1982) indicated that the curves of the variation of the heat and entropy of adsorption over the course of the isotherm provide supporting evidence for the validity of the monolayer value calculated by sorption equations. According to these authors, the crossover between the differential and integral enthalpy or entropy curves indicates the completion of the monolayer and the beginning of the multilayer (Cano-Higuita et al, 2015;Domínguez et al, 2007;Hill et al, 1951). The integral entropy can be qualitatively interpreted as the order-disorder of the adsorbed molecules.…”

Section: Thermodynamic Propertiesmentioning

confidence: 99%

Moisture adsorption isotherms of the borojó fruit (Borojoa patinoi. Cuatrecasas) and gum arabic powders

Rodríguez-Bernal

Flores-Andrade

Lizarazo-Morales

et al. 2015

Food and Bioproducts Processing

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Calculation of Thermodynamic Functions of Adsorbed Molecules from Adsorption Isotherm Measurements: Nitrogen on Graphon^1,2

Cited by 114 publications

References 0 publications

Chemical potential, Helmholtz free energy and entropy of argon with kinetic Monte Carlo simulation

Chemical potential, Helmholtz free energy and entropy of argon with kinetic Monte Carlo simulation

Heats of Adsorption of Krypton on Highly Graphitized Carbon Black

Moisture adsorption isotherms of the borojó fruit (Borojoa patinoi. Cuatrecasas) and gum arabic powders

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Calculation of Thermodynamic Functions of Adsorbed Molecules from Adsorption Isotherm Measurements: Nitrogen on Graphon1,2

Cited by 114 publications

References 0 publications

Chemical potential, Helmholtz free energy and entropy of argon with kinetic Monte Carlo simulation

Chemical potential, Helmholtz free energy and entropy of argon with kinetic Monte Carlo simulation

Heats of Adsorption of Krypton on Highly Graphitized Carbon Black

Moisture adsorption isotherms of the borojó fruit (Borojoa patinoi. Cuatrecasas) and gum arabic powders

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Calculation of Thermodynamic Functions of Adsorbed Molecules from Adsorption Isotherm Measurements: Nitrogen on Graphon^1,2