Distribution function, adsorption energy

Inverse Gas Chromatography at finite concentration conditions (IGC-FC) offers another possibility to perform such determinations. Furthermore, IGC readily provides the data required for the calculation of adsorption energy distribution functions. The aim of the present study was to... 

The first domain is used to determine the specific surface area (5 bet(H20)) and the BET constant values. Moreover, the large number of available experimental points allows the calculation of the corresponding adsorption energy distribution function of water on silica. 

Fig. 4. Adsorption energy distribution function (AEDF) of water on silica at 40 °C.

The last point concerns the water adsorption energy distribution functions that give a fingerprint of the surface energetic heterogeneity of the examined solids [3]. The adsorption energy distribution functions (AEDF) of water on the silica are displayed in Fig. 4. 

This study demonstrates the ability of IGC, at finite concentration conditions, to determine quickly (within one or two days depending on the desired accuracy) water adsorption isotherms, with relative pressures ranging from 0 to 0.85. Moreover, IGC provides isotherms made up of several hundreds of experimental points. This permits the computation of meaningful adsorption energy distribution functions. 

The samples were conditioned following the D160 protocol (conditioning at 160 °C, under dry carrier gas stream). The methylene chloride adsorption isotherms were determined on each sample and used to compute the BET surface area (5bet(CH2C12)), the corresponding BET constant (Cbet), and the adsorption energy distribution functions (AEDF). 

The surface energetic heterogeneity determination constitutes an additional aspect of the present study. This was performed by means of the methylene chloride adsorption energy distribution functions (AEDF) computation, relating the number of interactive surface sites to the desorption energy of each individual site. The latter are displayed in Fig. 1. 

Local adsorption energies, e, local adsorption isotherms, dip, T, e), local monolayer capacities, c ax, and adsorption energy distribution functions, /(e), for... 

In the above, the heterogeneity parameters nt and m characterize the shape (width and asymmetry) of adsorption energy distribution function, and the equilibrium constant, ATi , describes the position of distribution function on energy axis... 

Adsorption on heterogeneous surfaces is conveniently described in terms of ideal adsorption i.e., a process described by one or the other model described in the scheme of section 3.1.) on a surface characterized by an adsorption-energy distribution function ipiq), where ip q)dq respresents the fraction of surface with adsorption energy between q and q 4- d. This picture is usually referred to as homotattic patch approximation. 

Therefore, the surface heterogeneity of a solid may be obtained from the analysis of the adsorption isotherm profile and will be described in a form of an adsorption energy distribution function relating the number of adsorption sites having a given adsorption... 

Adsorption energy distribution functions measured at low temperature... 

Figure 12 shows the adsorption energy distribution functions of benzene for muscovites ground in the presence of the dimer of PAA and of IM KCL... 

Adsorption energy distribution functions of apolar (hexane) or polar probes (propanol and pyridine) are depicted in Figure 13, for an heritated illite and an heritated kaolinite. 

FIGURE 27.6 Adsorption energy distribution functions obtained from the simulated isotherms. N is the number of surface atoms replaced. (Reprinted from reference 41. With permission.)... 

FIGURE 1.6 Nitrogen adsorption energy distribution functions for different nanosilicas calculated using integral Fowler-Guggenheim equation. 

The complexity of the pores and the heterogeneity of the chemical structure of the pore walls cause the adsorption energy distribution function for LiChrolut EN strongly different from that for carbon adsorbents (see earlier), as well as the adsorption potential distribution functions/(A) (Figure 5.28). 

To calcnlate the adsorption energy distribution functions, the Fowler-Guggenheim (FG) equation was nsed to describe localized monolayer adsorption with lateral interactions ... 

Physical adsorption Isotherms of Ar and N2 on a-BN have been determined and analyzed. The adsorption energies distribution functions were calculated using a double Gaussian as distribution function. The Isosteric heats of adsorption were calculated employing the Clausius-Clapeyron equation. Both systems display a sharp maximum upon completion of a statistical monolayer (see Fig. 4-21). For additional Information, see [50]. 

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