Binary adsorption effects

There is a number of very pleasing and instructive relationships between adsorption from a binary solution at the solid-solution interface and that at the solution-vapor and the solid-vapor interfaces. The subject is sufficiently specialized, however, that the reader is referred to the general references and, in particular, to Ref. 153. Finally, some studies on the effect of high pressure (up to several thousand atmospheres) on binary adsorption isotherms have been reported [154]. Quite appreciable effects were found, indicating that significant partial molal volume changes may occur on adsorption. 

The effect of the pore network connectivity on the prediction of binary adsorption equilibria is studied. The Ideal Adsorbed solution theory (lAST) is used in conjunction with modified DR single component isotherm, and it is found that incorporation of the connectivity... 

P-2S - The use of binary adsorption studies to investigate the effect of hydrothermal treatment on zeolites Rho and Mordenite... 

Azeotrope formation and selectivity reversal appear to be fairly common features of binary adsorption equilibrium behavior but are not predicted by most of the simpler models such as Eqs. (4.11) or (4.16). Such behavior is predicted by Eq. (3.102) when the effective molecular volumes of the components are different and the component with the smaller volume also has the smaller Henry constant but only at relatively high sorbate concentrations. The experimental data for C2H4-CjHg in 5A show that selectivity reversal occurs even at relatively low loading (high temperatures) and is much more... 

Activated carbons have a spread of pore sizes. Consequently the possibility that they can show a partial molecular sieve effect cannot be overlooked when the components of the binary solution are not of the similar molecular dimensions. This factor would add a degree of preferential adsorption of the components of smaller size molecules irrespective of the competitive adsorption due to other factors. The composite isotherms would, therefore, be of the type obtained on heterogeneous surfaces. This competitive adsorption effect wiU be more prominent and visible when carbons are produced from the same source raw materials by different procedure or post preparation treatments. For example, carbons that have been produced after varying degrees of activation or carbons that are heat treated at varying temperatures after activation will have different porosities and pore size distribution. The extremely fine micropores get partially blocked as the final heat treatment temperature exceeds 800°C to 900°C, due to the calcinations of the pores. This will produce molecular sieve effect depending upon the heat treatment temperature. 

The binary adsorption data clearly demonstrates the existence of a total pressure range in which the capacity of an adsorbent for CH4 and N2 is maximum. The "adsorption enhancement factor" correlationfor N2 andCH4, though restricted to one temperature in this investigation, should be useful in predicting capacities and total pressure effect on other adsorbents as well as providing a basis for evaluating theoretical ehancement curves. 

Ir catalysts supported on binary oxides of Ti/Si and Nb/Si were prepared and essayed for the hydrogenation of a,P-unsaturated aldehydes reactions. The results of characterization revealed that monolayers of Ti/Si and Nb/Si allow a high metal distribution with a small size crystallite of Ir. The activity test indicates that the catalytic activity of these solids is dependent on the dispersion obtained and acidity of the solids. For molecules with a ring plane such as furfural and ciimamaldehyde, the adsorption mode can iirfluence the obtained products. SMSI effect (evidenced for H2 chemisorption) favors the formation of unsaturated alcohol. 

Connors and Jozwiakowski have used diffuse reflectance spectroscopy to study the adsorption of spiropyrans onto pharmaceutically relevant solids [12]. The particular adsorbants studied were interesting in that the spectral characteristics of the binary system depended strongly on the amount of material bound. As an example of this behavior, selected reflectance spectra obtained for the adsorption of indolinonaphthospiropyran onto silica gel are shown in Fig. 1. At low concentrations, the pyran sorbant exhibited its main absorption band around 550 nm. As the degree of coverage was increased the 550 nm band was still observed, but a much more intense absorption band at 470 nm became prominent. This secondary effect is most likely due to the presence of pyran-pyran interactions, which become more important as the concentration of sorbant is increased. 

Bimolecular surface reactions reactants adsorption, 29 111-112 with single reactant, 29 108-109 1,1 -Binaphthyl, dehydrocyclization, 28 318 Binary oxides, 32 119 Binding energy, 32 160-162 chemisorbed sulfur, 37 281 hydrogen, sulfur effect, 37 295-296 shift, Pd, 37 62-64 ZnO/SiOj, 37 21-22 Binor-S, see Norbomadiene Biological systems, hydrogen in, activation of, 11 301... 

Zn/AljOj catalysts, 31 249 -Zn/Cr Oj catalysts, 31 250 -ZnO/AljO, 31 276, 292-295 -ZnO binary catalyst, 31 257-287 activity patterns, 31 271-274 BET argon surface areas, 31 259 calcination, 31 261-262 catalytic testing, 31 272 chemisorption, 31 268-271 CO2 effects, selectivity, 31 284-285 color spectra, 31 259-261 component comparison, 31 258-259 methanol synthesis, 31 246-247 modifiers, weakening of adsorption energy, 31 283... 

Acyl chain length, effect on binary phase diagram of G type nonionics, 42 Adhesion, LAS detergency performance, 250f Adsorption... 

With some simplification, theoretical models of adsorption lead to Equation 5.10 describing the effects of increasing concentration of the stronger (more polar) solvent, q), on decreasing retention factor, k in binary organic mobile phases [53] ... 

If the compositional difference along the diffusion direction is primarily in one component, and the difference in other components is due to the dilution effect, then diffusion of this component (not necessarily the other components) may be treated as effective binary, and the EBDC can be applied reliably to similar situations. Some examples are a diffusion couple made of dry rhyolite on one half and hydrous rhyolite on the other half, the hydration or dehydration of a silicate melt, and adsorption of a gas component by a glass. 

In order to elucidate the effect of alkyl alcohol on the surface adsorption of CyFNa and C,oSNa, it is useful to calculate the surface molecular interaction parameters of the binary surface active mixtures (y8,) according to the equation at constant surface tension and constant ionic strength (13,14,10) ... 

Effective Diffusivity. The effective diffusivity for N2/He at 25° C was calculated from the slope of the straight-line portion obtained in the high velocity region of a van Deemter plot [height of an equivalent plate vs. interstitial velocity 14, 15)]. A binary diffusion coefficient for N2-He of 0.717 cm2/sec was computed from Ref. 21, and the partition coefficient was taken as the reciprocal of the particle porosity (Table III) on the assumption that the adsorption of N2 at 25° C can be neglected. The calculated diffusivities are listed in Table III. 

Finally, intraparticle diffusion appears to be an important factor in adsorption kinetics for many types of systems. In the past it has been customary to define such mass transfer quantitatively in terms of an effective diffusivity. However, even in gas-solid systems more than one process can be involved for porous particles. Thus, two-dimensional migration on the pore surface, surface diffusion, is a potential contribution. Liquid systems appear to be more complex, and, with electrolytes, it has been shown that the electric potential induced by counter-diffusing ions should be taken into account. A realistic description of intraparticle mass transfer in such cases requires more than a single rate coefficient for a binary system. 

At present, the binary water-soluble preparation of heparin and proteolytic enzymes is being applied for the treatment of thromboses. For instance, injection into the bloodstream of heparin-plasmin complex or a heparin-plasmin-streptokinase preparation leads to the total dissolution of the thrombus, while if introduced separately, heparin and streptokinase do not display the lytic action at all, and plasmin, alone or together with streptokinase, dissolves the thrombus only partially 132>. The treatment of acute thrombophlebitis with trypsin resulted in a full dissolution of the thrombus and in an increase of antithrombin III in the blood 133). Administration of trypsin together with heparin has an effect similar in efficiency to the action of the heparin-plasmin complex 134>. The use of a mix of heparin and urokinase for improving tbrom-boresistance of polymeric materials was also described 13S). These substances were immobilized by preliminary coating of the surface of a polymer with a graphite layer and subsequent adsorption of heparin and the enzyme. 

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