Henry adsorption coefficient

Hence, the selectivity in GSC is determined by the values of the Henry adsorption coefficients of the two solutes. 

Measured and Simulated Heats of Adsorption as Well as Henry Adsorption Coefficients for Linear Hydrocarbons in Siliceous Zeolites... 

An analogous law was established in 1803 by W. Henry for the solubilities of gases in water hence, this expression is called the Henry isotherm. The adsorption coefficient B (units dmVmol) depends on the heat of adsorption B = B° e,xp(q RT). The Henry isotherm is valid for low surface coverages (e.g., at 9 < 0.1). 

Just as the Henry law constant is used to quantify the partitioning between air and water, it is useful to define a parameter to quantify the partitioning between soil and water. The linear adsorption coefficient, Kd, has often been defined for this purpose ... 

Spencer et al. (14) reported that the degree of reduction in vapor pressure in soil due to adsorption is dependent mainly upon soil water content, the nature of the pesticide, its concentration and soil properties, particularly soil organic matter content. The concentration of the desorbed pesticide in the soil water dictates the vapor density of the pesticide in the soil air in accordance with Henry s law. Hence, soil water adsorption coefficients can be used to calculate relative vapor densities in the soil atmosphere. 

Gas solubilities in water are also reported as Bunsen ad.sorption coefficients (cf. Pagenkopf 1978), or in terms of mole fractions dissolved (cf. Bodek et al. 1988). The Bunsen adsorption coefficient, a, is related to the Henry s law constant through the expression - anl22A 4. 

Henry s coefficient, (mol/m )Hquid/(niol/m )gj5 adsorption equation constant for Langmuir-Hinshelwood kinetics, m mol... 

The rate at which a chemical volatUizes from soil is controlled by simultaneous interactions between soil properties, chemical s properties and environmental conditions. Soil properties that affect volatilization include soil water content, organic matter, porosity, sorption/diffusion characteristics of the soil, etc. chemical s properties that affect volatilization include vapour pressure, solubility in water, Henry s law constant, soil adsorption coefficient, etc. and finally, environmental conditions that affect volatilization include airflow over the surface, humidity, temperature, etc. VolatUization rate from a surface deposit depends only on the rate of movement of the chemical away from the evaporating surface and its vapour pressure. In contrast, volatilization of soil-incorporated organic chemicals is controlled by their rate of movement away from the surface, their effective vapour pressure at the surface or within the soil, and their rate of movement through the soil to the vapourizing surface. 

The data for retention on a solid stationary phase transform into equilibrium adsorption coefficients in the same manner as GLC retention data except that the mass or volume are replaced by surface as an extensive variable characteristic for the stationary phase [123]. In the region where Henry s law applies, the surface concentration F is ... 

Values of Henry s law constant k =plc, where p is the partial pressure of the solute in the gas above the solution and c is the concentration of the solute) is a quantity frequently apphed in the thermodynamic description of dilute aqueous solutions, which is used in environmental chemistry and atmospheric physics as a major criterion for describing air-water partitioning of solutes at near ambient conditions. It plays amajor role in evaluating the transport of pollutants between atmosphere and aquatic systems, rainwater and aerosols. The octanol-water partition coefficient is a dimensionless number defined as the ratio of the compound s concentration in a known volume of octan-l-ol (Cq) to its concentration in a known volume of water (c ) after the octan-l-ol and water have reached equihbrium. It has been found to be related to water solubility, soil/sediment absorption coefficients and bioconcentration factors of pollutants for aquatic life. The adsorption coefficient normalised to the organic carbon content of the soil (sediment) is a useful indicator of the binding capacity of... 

Adsorption of a fluid quantified by the surface solubility coefficient according to Henry s law... 

Based on equations (3.25) and (3.26) for the linear area of adsorption of dissolved oxygen on a thin semiconductor film (F being the Henry coefficient), we can derive the following equation ... 

Table I shows the results of calculating a soil diffusion coefficient and soil diffusion half-lives for the pesticides. The 10% moisture level specified means that the soil is relatively dry and that 40% of the soil volume is air available for diffusion. Complete calculations were not made for methoxychlor, lindane, and malathion because, based on Goring s criteria for the Henry s law constant, they are not volatile enough to diffuse significantly in the gas phase. This lack of volatility is reflected in their low values of X. These materials would move upward in the soil only if carried "by water that was moving upward to replace the water lost through evapotranspiration at the surface. Mirex has a very high Henry s law constant. On the basis of Goring s criteria, Mirex should diffuse in the soil air but, because of its strong adsorption, it has a very large a and consequently a very small soil air diffusion coefficient. The behavior of Mirex shows that Goring s criteria must be applied carefully.

Adsorption constant, Henry s Law coefficient, slope of the chord of the isotherm, dimensionless... 

In the limit of low pressure the front end of the adsorption isotherm is approximated by the Henry regime which states that the number of adsorbed molecules per unit volume is proportional to the pressure and to the Henry coefficient, Kh. ... 

Here kgr is the surface reaction rate constant, Rr is the adsorption equilibrium constant for product R, Pr is the partial pressure of R and Kp is the reaction equilibrium constant. At low loading the reaction rate simply becomes proportional to the product of the intrinsic rate constant and the Henry coefficient. 

For propane, n-pentane and n-hexane the differential heats of adsorption over FER dropped more rapidly, right after 1 molecule was adsorbed per Bronsted acid site. Similar results were obtained with TON. In contrast, with MOR and FAU the drop in the differential heats of adsorption for n-alkanes occurred at lower coverages, indicating that only a certain fraction of the Bronsted acid sites were accessible to the adsorbing alkane probe molecules. With MFI the drop did not occur until 2 molecules of n-alkane were adsorbed per Bronsted acid site, suggesting perhaps a higher stoichiometry of about two n-alkanes per Bronsted acid site. In the cases of i-butane and i-pentane the drop occurred around one alkane per Bronsted acid site. Finally, n-butane adsorption isotherms measured over TON framework type catalysts having three different A1 contents (Si/Al2 = 90, 104, 128) showed Henry coefficients to increase with increase in the A1 content [5], Based... 

Often the ratio of Henry coefficients, related to adsorption at zero loading, is used for predicting the selectivity of adsorption for mixtures. The ratio of Henry coefficients for linear and mono-branched alkanes with carbon number n = 5-8 are summarized for various zeolites in Figure 13.10 [15]. The Henry coefficient ratios were 1 for FAU, 2 for BEA, MOR and MFI, 6-9 for TON and 10-14 for MTT. Interestingly, CBMC simulations suggest that the ratio of Henry coefficients, actu-... 

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