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Fractionation of adsorption

Assume, that there are adsorption particles with concentration Nt on the surface of semiconductor which is in adsorption equilibrium with a certain gas. A fraction of adsorption particles is charged with concentration designated as w<. Apart from them, on the surface there are various biographic surface states with concentration of the charged particles ng controlling the degree of an a priori band bending qUso-... [Pg.28]

In order for a molecule to ultimately adsorb, it must first collide with the surface with sufficient energy to overcome any activation barrier, indicated as in Figure 5.9. The Ea can be negligibly small, as in physisorption, or can be significant, as in the case of chemical reactions. The rate at which adsorption proceeds will depend on an adsorption rate constant k, on the concentration or partial pressure of the adsorbing species (p), and on the fraction of adsorption sites that are unoccupied. Thus, we can express die adsorption rate as... [Pg.267]

It follows from this Fig. that the amount of chemical junctions in silicon rubber increases with increasing fractions of Aerosil. The chemical junctions are apparently formed by scission of PDMS chains under the mechanical forces during milling. However, the fraction of these junctions is the lowest. The fraction of adsorption junctions increases proportionally to the filler content as shown in Fig. 11. The major contribution to the network structure is provided by topological hindrances near the filler surface as shown in Fig. 11. [Pg.798]

Derive from kinetic principles the competitive Langmuir equation for gas adsorption, that is, a function that expresses the fraction of adsorption sites occupied by molecule A in the presence of an adsorbing molecule B. [Pg.392]

Addition of a surfactant can further enhance the flocculation at the ultralow polymer dosage regime. As shown in Figure 7.37, the addition of anionic surfactant (SDS) significantly improves the flocculation at very low polymer concentrations. At higher polymer levels, the surfactant addition has no effect on flocculation. This is probably due to a significant fraction of adsorption sites already occupied by polymer, making them unavailable for adsorption of the surfactant molecules. [Pg.433]

Defining the fraction of adsorption sites covered by A as 0o = a/p> be equilibrium constant for the adsorption equilibrium as Aa = ka/kd, the above equation reduces to... [Pg.765]

Being Ca the concentration of the adsorbate in the liquid phase (mg L-i), Icad the kinetic constant of adsorption, ko the kinetic constant of desorption and 6U the fraction of adsorption sites occupied by component A of the total number of sites occupied at... [Pg.281]

TABLE 31.2. Estimated fractions [%] of adsorption sites i-iV at the surfaces of the four examined c.b. sampies... [Pg.549]

The rate of the anodic partial reaction, v a > is proportional to the amount of adsorbed hydrogen, expressed by the coverage which represents the fraction of adsorption... [Pg.186]

As before the correlation curves 8i(), where is the volume of adsorption space occupied, are calculated from the single solute isotherms and, for given bulk phase compositions the free-energy curves, as functions of (f>, calculated for each component. The fraction of adsorption space occupied by a given component is that in which its free-energy curve is the lowest. In this way. [Pg.117]

A macromolecule blockades a certain number of adsorption sites, screening them from the penetration of other macromolecules. Apparently, the number of blockaded sites must depend on the size of the macromolecule coil and, therefore, on the degree of polymerization. In our opinion, as a first approximation, the fraction of adsorption sites blockaded by an adsorbed polymer can be described as follows ... [Pg.771]

However, this correlation is not real, first, because the surface energy is not uniform and secondly, it doesn t form a complete mruiolayer, but several layers. Thus, there is interaction between the gas molecules and the adsorbed molecules at the surface, besides a great mobility of the molecules, which doesn t meet the Langmuir hypotheses. However, for low coverages and low relative pressures, this equation can be used allowing to calculate the fraction of adsorption at the surface or the volume of adsorbed molecules. [Pg.103]


See other pages where Fractionation of adsorption is mentioned: [Pg.31]    [Pg.101]    [Pg.152]    [Pg.404]    [Pg.1344]    [Pg.37]    [Pg.69]    [Pg.1826]    [Pg.103]    [Pg.392]    [Pg.368]    [Pg.402]    [Pg.1818]    [Pg.1526]    [Pg.1472]    [Pg.149]    [Pg.253]    [Pg.108]    [Pg.120]    [Pg.384]    [Pg.229]    [Pg.232]   
See also in sourсe #XX -- [ Pg.405 ]




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