Langmuir adsorption coefficients

Cmax is the maximum concentration of solute that can be adsorbed by the soil, and K is the Langmuir adsorption coefficient. Combining the above two equations, a quadratic equation can be derived in terms of Cs, which on solving for the positive root gives... 

A (ext) or a(ext) external surface area b Langmuir adsorption coefficient... 

Langmuir adsorption coefficient overall mass transfer coefficient individual mass transfer coefficients at G-L interface ibid, at liquid-solid interface homogeneous reaction velocity... 

Another limitation of tire Langmuir model is that it does not account for multilayer adsorption. The Braunauer, Ennnett and Teller (BET) model is a refinement of Langmuir adsorption in which multiple layers of adsorbates are allowed [29, 31]. In the BET model, the particles in each layer act as the adsorption sites for the subsequent layers. There are many refinements to this approach, in which parameters such as sticking coefficient, activation energy, etc, are considered to be different for each layer. 

In classical kinetic theory the activity of a catalyst is explained by the reduction in the energy barrier of the intermediate, formed on the surface of the catalyst. The rate constant of the formation of that complex is written as k = k0 cxp(-AG/RT). Photocatalysts can also be used in order to selectively promote one of many possible parallel reactions. One example of photocatalysis is the photochemical synthesis in which a semiconductor surface mediates the photoinduced electron transfer. The surface of the semiconductor is restored to the initial state, provided it resists decomposition. Nanoparticles have been successfully used as photocatalysts, and the selectivity of these reactions can be further influenced by the applied electrical potential. Absorption chemistry and the current flow play an important role as well. The kinetics of photocatalysis are dominated by the Langmuir-Hinshelwood adsorption curve [4], where the surface coverage PHY = KC/( 1 + PC) (K is the adsorption coefficient and C the initial reactant concentration). Diffusion and mass transfer to and from the photocatalyst are important and are influenced by the substrate surface preparation. 

SULFATE ADENYLYLTRANSFERASE (ADP) ADRENODOXIN ADSORPTION ABSORPTION BIOMINERALIZATION MICELLAR CATALYSIS LANGMIUR ISOTHERM Adsorption coefficient LANGMUIR ISOTHERM Adsorption of gases,... 

The model followed single-site, nondissociative, Langmuir-Hinshelwood poisoning. This resulted in the same adsorption coefficients for deactivation and start-of-cycle kinetics. 

The fractional factor with p of Equation (1) according to the accepted view corresponds to Langmuir s adsorption isotherm for mixtures on an almost covered homogeneous surface or on like active centers and the z are the relative adsorption coefficients. This fraction was so interpreted for other cases by Hinshelwood 13), Schwab 9), the author 1, 14), Frost 15), Hougen 16), and others. Two questions now arise ... 

TABLE 4.7. Adsorption Coefficients (K) and Distribution Coefficients (Kd) for Adsorption of Triallate (Linear Isotherms) and trans- and c/s-Chlordane (Langmuir Isotherms) on Humic Acids (HAs) Isolated from Pig Slurry (PS) and Surface (1) and Whole (2) Horizons of Two Soils (UK and PO)... 

There are several theoretical derivations of adsorption isotherms. The simple Langmuir equation [Eq. (4.2), named after the American chemist and 1932 Nobel laureate Irving Langmuir], describes the formation of a monolayer on a surface [81]. This corresponds to the type I isotherm shown in Figure 4.15. Here Vis the amount adsorbed, Vm is the amount adsorbed in one monolayer, p is the pressure and b is the adsorption coefficient, which depends exponentially on the heat of adsorption. 

Determine the Freundlich and Langmuir isotherm coefficients for the following adsorption test data on granular activated carbon (GAC). The liquid volume used in the batch adsorption tests was 1 L. The initial concentration of the adsorbate in solution was 3.37 mg/L. Equilibrium was obtained after 7 days. 

Adsorption at a charged sur u% where both electrostatic and specific chemical interactions are involved can be discussed in terms of the Langmuir adsorption isotherm, where the distribution coefficient b is given by the exponential of a sum of the electrochemical and electrostatic forces. In this treatment the fractional surface coverage, 6, is given by [43]... 

Different charge-compensating cations in zeolite L have been tested for their promotional effect in n-hexane aromatization. Apparently, high basicity of the alkaline and alkaline earth promoter favors n-hexane aromatization. Basicity and selectivity both increase from Li and Cs 331) and from Mg to Ba (22,25). Bezouhanova et al. studied the FTIR bands of linearly adsorbed CO in the range of 2060-2075 cm . One band at 2075 cm", which is also found on unsupported Pt, is attributed to extrazeolite Pt particles, a second band shifts from 2060 cm" for Li to lower wavenumbers with K and Rb 331). Another criterion, used by Larsen and Haller, is the measured rate of competitive hydrogenation of benzene and toluene, which has been found to correlate with the zeolite basicity (25). As described in a previous section, this method had previously been used by Tri el al. to probe for the electron deficiency of Pt particles in acidic zeolites 332). The rate data are analyzed in terms of a Langmuir-Hinshelwood model and the ratio of the adsorption coefficients of toluene and benzene, A, /b, is determined. It was found to decrease from 8.6 for Pt/Si02, and 5.4 for Pt/MgL, to 4.4 for Pt/BaL. As direct electron transfer from the cations to neutral Pt particles is unlikely, an interaction of Pt with the zeolite framework or with... 

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