Adsorbate mixtures

Consider a binary adsorbed mixture for which each pure component obeys the Langmuir equation, Eq. (16-13). Let n = 4 mol/kg, nl =. 3 mol/kg, Kipi = K2P2 = 1. Use the ideal adsorbed-solution theory to determine ni and n. Substituting the pure component Langmuir isotherm... 

As a second example, consider the partitioning of Cd(II) between two adsorbents—a-TiC and (am)Fe20j.H20. Figure 11 shows Cd(II) fractional adsorption as a function of pH for binary mixtures of these adsorbents under experimental conditions such that Cddl) and SOUp are constant only the surface site mole fraction varies from one end-member to the next. As the site mole fraction shifts between the end-members, the fractional adsorption edges for the binary adsorbent mixtures varies between the limits defined by end-members. In the absence of particle-particle interactions, the adsorbents should act as independent ligands competing for complexa-tion of Cd(II). If this is the case, then the distribution of Cd(II) in such binary mixtures can be described by a composite mass-action expression (13) which includes a separate term for the interaction of Cd(II) with each adsorbent. 

In essence, there are two alternative ways in which emulsion droplets can be stabilized by an adsorbing mixture of protein + polysaccharide ... 

Abstract We formulate the balance principles for an immiscible mixture of continua with micro structure in the broadest sense for include, e.g., phenomena of diffusion, adsorption and chemical reactions. After we consider the flow of a fluid/adsorbate mixture through big pores of an elastic solid skeleton and propose suitable constitutive equations to study the coupling of adsorption and diffusion under isothermal conditions. 

The cyclohexane-adsorbent mixture gave a capacitance corresponding to an overall dielectric constant of 3.267. Based on the adsorbent volume fraction, the Looyenga (10) equation yielded a value of 16.4 for the dielectric constant of the adsorbent. 

The solid lines on Figure 4 take into account the nonideal behavior of adsorbed mixtures of ethylene and ethane in NaX. This system is highly nonideal because of the interaction of the quadrupole moment of ethylene with the soditun cations of NaX. Activity coefficients at infinite dilution are unity at the limit of zero pressure and 0.27 at high pressure. The dashed lines on Figure 4 were calculated for am ideal adsorbed solution (IAS) and the resulting error in the individual isotherm for ethane at 30 bar is 20%. 

A product of the Mallinckrodt Chemical Works, St, Louis, Mo. The adsorbent mixture was silicic acid/Celite No, 535 (3/1). 

The first in-situ application of FT PFG NMR during chemical reaction was reported by Hong et al. [17] for the conversion of cyclopropane to propene in zeolite X. The self-diffusivities of the two species in the adsorbed mixture were found to be essentially the same, and they remained constant during the course of the reaction. One of the important results was that for such a system the diffusivities under reaction conditions could be extrapolated from the diffusivities determined at lower temperatures where no chemical reaction took place. 

In summary, the procedure for predicting the thermodynamic properties of an adsorbed mixture begins with the determination of the thermodynamic properties of each individual component as expressed by its equation of state. Equation (5). After fixing the independent variables T, P, yj for a system containing components, the set of (2iVp—1) Equations (13)-(15) is solved for the adsorbed-phase mole fractions X and standard-state amounts adsorbed ( "), with the constraint that... 

By making use of the adsorbability of TPs semiconductor particles for photoelectrochemical cells are provided with an adsorbed mixture of dye and TP (e.g., 2) (00JAP(K)228233). Finally, TP carboxylic acids can be contained in compositions for depositing silver layers (plating) (04USP40852). 

It has further been discovered that the mycella-adsorbent mixture can be separated from the liquid component in a relatively facile manner through filtration or other physical separation means. 

A still further surprising discovery was that after physical separation, the mycella-adsorbent mixture containing the alkaloids can be subjected to fluidized bed drying according to the known physical parameters at the normally unfavorably high temperature for the alkaloids of 80°-90° C. without isomerization or decomposition of the compounds. After a washing with a weak aqueous alkaline solution, the alkaloids can then be extracted easily and virtually completely from the dry mycella-adsorbent mixture with an organic aprotic solvent. 

L. of the culture suspension of Example 1 is stirred for 1 hour with 5 kg of bleaching earth, filtered, and the mycella-adsorhate mixture is dried in the fluidized hed at 80°-90° C. for about 15 minutes until an exhaust temperature of 50° C. is reached. There is recovered 12 kg of the dried mycella-adsorbent mixture with a residual moisture content of 10-12% and an alkaloid content of 92-100% based on the culture suspension. 

Kg. of the dry mycella-adsorbent mixture of Example 1 or 2 is mixed with 7.5 L. of 1 1 diluted ammonia, extracted in a mechanical extractor with 150 L. chloroform or methylene chloride over 45 minutes, filtered under pressure and the process repeated with the same volume of solvent for 30 minutes. The total extract is added to an equal volume of 5% aqueous acetic acid and processed in a separator, the aqueous phase constantly adjusted to pH 9 the process is repeated a second time with the same solvent or with ethylene acetate at a double volume. After evaporation and isolation of the ergometrin and ergotoxin, the adducts and yields of an alkaloid content of 96 to 103% calculated as the bimaleinate. The yield is approx.) 351.6 g ergotoxin-toluol adduct, 72% calculated from the culture suspension and 243 g ergometrin-chloroform adduct, 82% from the suspension. 

L. culture solution of Claviceps purpurea IMET PA 134 at its natural pH value (5-6) is stirred for 30 minutes with 1.2 kg bentonite. It is then filtered through a layer of calcium sulfate dihydrate and the filtrate discarded. Dr3ung of the mycella-adsorbent mixture according to Example 1 yields 2.8 kg of the dry mixture, which contains practically all of the alkaloid content of the culture suspension (ergosine, ergosinine, traces of chanoclavine). Rotary extraction of the alkaloids with a 10 to 12 fold volume of ethyl acetate yields up to 90% of the alkaloid content of the dry mycella-bentonite mixture. 

The fifth approach is more a field than a concise method, since it embodies so many theoretical concepts and associated methods. All are grouped together as adsorbed mixture models. Basically, this involves treating the adsorbed mixture in the same manner that the liquid is treated when doing VLE calculations. The major distinction is that the adsorbed phase composition cannot be directly measnred (i.e., it can only be inferred) hence, it is difficult to pursue experimentally. A mixture model is nsed to account for interactions, which may be as simple as Raoult s law or as involved as Wilson s equation. These correspond roughly to the Ideal Adsorbed Solution theory and Vacancy Solution model, respectively. Pure component and mixture equilibrium data are required. The unfortunate aspect is that they require iterative root-finding procedures and integration, which complicates adsorber simnlation. They may be the only route to acceptably accurate answers, however. It would be nice if adsorbents could be selected to avoid both aspects, but adsorbate-adsorbate interactions may be nearly as important and as complicated as adsorbate-adsorbent interactions. 

The oil-adsorbent mixture is heated to a temperature appropriate to the oil being processed, usually to 70° to 120° C. When the proper temperature is reached, the mixing is continued for 10-30 minutes, after which the batch is pumped through a filter to remove the adsorbent. Some of the oil retained by the adsorbent can be removed by blowing the press cake with steam or by extraction with a solvent. Complete recovery is seldom practical because the firmly held oil contains impurities and is of poor quality. 

As a last resort, the sample can be adsorbed on a small portion of adsorbent by gradually concentrating a slurry of sample solution plus adsorbent. The resulting adsorbent plus adsorbed sample is then placed at the front of the bed and separation is begun. The solvent used in the preparation of the sample-adsorbent mixture must be weak enough so that adsorption is favored over precipitation, otherwise the whole purpose of this technique is set to nought. 

However, the adsorption and adsorption kinetics of binary or even more complex adsorbate mixtures are of paramount importance in gas separation and catalysis. Thus, even in the simplest case of the conversion of a reactant A into a product M inside the pore system of a zeolite catalyst, the... 

In Fig. 2.4-18 the basic equations of the lAST model are illustrated for a binary adsorbate mixture. The relationships 1/4 and // of the reduced spreading pressure are drawn against the total pressure p of the binary system. In the case of equilibrium both components have the same reduced spreading pressure // = y/ = y/. This common reduced spreading pressure can be found between the two vp -curves for a given pressure p. The exact position of y/ in the diagram is determined by the mole fractions and y, of the components a and b in the gas phase ... 

The point of intersection of the y/= const, line with the curves 1/4 (p) and y/, ip) leads to the hypothetical vapor pressures and pi and also to the mole fractions and of the adsorbate mixture ... 

The activity coefficients of binary adsorbed mixtures must be computable from single component adsorption isotherms or the heat of adsorption of the pine components or the physical properties of the adsorbed molecules (polarity, polarizability, etc). 

For multicomponent systems obeying the ideal adsorption solution theory, the spreading pressure of the adsorbed mixture is n. The partial pressure of the species i in the gas phase is related to the hypothetical pure component pressure which gives the same spreading pressure n as that of the mixture according to the Raoult s law analogy ... 

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