Adsorption separation

The extensive use of the Young equation (Eq. X-18) reflects its general acceptance. Curiously, however, the equation has never been verified experimentally since surface tensions of solids are rather difficult to measure. While Fowkes and Sawyer [140] claimed verification for liquids on a fluorocarbon polymer, it is not clear that their assumptions are valid. Nucleation studies indicate that the interfacial tension between a solid and its liquid is appreciable (see Section K-3) and may not be ignored. Indirect experimental tests involve comparing the variation of the contact angle with solute concentration with separate adsorption studies [173]. 

The separate adsorption isotherms for gases A and B on a certain solid obey the Langmuir equation, and it may be assumed that the mixed or competitive adsorption obeys the corresponding form of the equation. 

Ebex process separation [ADSORPTION, LIQUID SEPARATION] (Voll)... 

See Adsorption Adsorption, gas separation Adsorption, liquid separation. 

Adsorption (qv) of gases has been reviewed (40,50) (see also Adsorption, gas separation). Adsorption, used alone or in combination with other removal methods, is excellent for removing pollutant gases to extremely low concentrations, eg, 1 ppmv. When used in combination, it is typically the final step. Adsorption, always exothermic, is even more attractive when very large gas volumes must be made almost pollutant free. Because granular adsorbent beds ate difficult to cool because of poor heat transfer, gas precooling is often practiced to minimize adsorption capacity loss toward the end of the bed. Pretreatment to remove or reduce adsorbable molecules, such as water, competing for adsorption sites should also be considered (41). 

Ordinary diffusion involves molecular mixing caused by the random motion of molecules. It is much more pronounced in gases and Hquids than in soHds. The effects of diffusion in fluids are also greatly affected by convection or turbulence. These phenomena are involved in mass-transfer processes, and therefore in separation processes (see Mass transfer Separation systems synthesis). In chemical engineering, the term diffusional unit operations normally refers to the separation processes in which mass is transferred from one phase to another, often across a fluid interface, and in which diffusion is considered to be the rate-controlling mechanism. Thus, the standard unit operations such as distillation (qv), drying (qv), and the sorption processes, as well as the less conventional separation processes, are usually classified under this heading (see Absorption Adsorption Adsorption, gas separation Adsorption, liquid separation). 

In the CIL process leaching and adsorption are not carried out separately but are combined into one operation. In this process the first tank is used only for leaching, while leaching and adsorption occur simultaneously in the remaining tanks. Since it is not necessary to build a separate adsorption section, there is an advantage in terms of savings in capital investment associated with the CIL systems. 

Desorption Displacement desorption Gas separation adsorption Liquid separation adsorption Pressure swing adsorption Thermal swing adsorption asbestos fibers, 3 304 for bioremediation, 3 782 capillary condensation, 1 585, 591 dessicants and, 3 375-377 detergency and, 3 428 129 in dispersions, 3 707 filler measurement via, 22 571 general separation heuristics for,... 

Antibodies, 20 831 functional, 12 475 liquid separation adsorption, 1 678 oligonucleotides attached to, 17 635 yeast-derived, 26 486 Antibody-analyte complex, 14 138 Antibody-antigen binding event, 14 137-138... 

See also Gas separation adsorption adsorbents for, 1 612 coal gasification, 6 824 commercial separations, l 618t hollow-fiber membrane modules for, 15 823... 

See also Liquid separation adsorption Liquid separation adsorption, 1 664-691 adsorbate-adsorbent interactions,... 

Zeolite Y, 2 345t, 5 238-239, 11 678, 679 coke formation on, 5 270 for liquid separation adsorption, 1 674 manufacture, 2 359 structure, 1 675 Zeolite ZSM-5, 11 678 Zeolitic cracking catalysts, 16 835 Zeolitic deposits, 16 813 Zeonex, 10 180 Zeotypes... 

Adsorption-desorption equilibrium for Cd(II) on illite after 54 days of equilibration. The solution contains HCO3, 2 x 10 3 M Ca2+ and has a pH = 7.8. Freundlich isotherms based on separate adsorption ( ) and desorption (O) data are given from Comans (1987). 

Zeolites can be ion-exchanged with cations or impregnated with various metals to modify their performance for use in applications such as separations, adsorption and catalysis. For example, faujasite zeolites exchanged with Na, Li, K, Ca, Rb, Cs, Mg, Sr, Ba, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ru, Pd, Ag, Cd, In, Pt, H, Pb, La, Ce, Nd, Gd, Dy and Yb have been made and studied due to their use in separation and catalysis [135]. The ability to determine the distributions of these cations in the zeolitic structure is one of the key parameters needed in understanding adsorption mechanisms and molecular selectivities. Little has compiled an excellent reference... 

The second part of the book covers zeolite adsorptive separation, adsorption mechanisms, zeolite membranes and mixed matrix membranes in Chapters 5-11. Chapter 5 summarizes the literature and reports adsorptive separation work on specific separation applications organized around the types of molecular species being separated. A series of tables provide groupings for (i) aromatics and derivatives, (ii) non-aromatic hydrocarbons, (iii) carbohydrates and organic acids, (iv) fine chemical and pharmaceuticals, (v) trace impurities removed from bulk materials. Zeolite adsorptive separation mechanisms are theorized in Chapter 6. 

Licsko, I. Dissolved organics removal by soUd-liquid phase separation (adsorption and coagulation). Water Sci. Technol. 1993, 27 (11), 245-248. 

One could think about measuring b directly in a separate adsorption experiment. However, it has been found that the adsorption thus measured has no quantitative relation to the adsorption leading to a catalytic reaction. Not only the amounts adsorbed, but even the shape of the isotherm and the sensitivity to poisoning or surface alterations are totally different. The reason is that the adsorption experiment measures the total surface under favorable conditions (B.E.T. method), whereas the catalysis takes place on a quantitatively entirely different active ... 

Based on capacity factor measurements, a pH of 5.0 was chosen for the separations. Adsorption isotherms were measured and found to exhibit almost ideal Langmuirian behavior for the proteins and for the displacer. In agreement with capacity factor measurements, a displacement performed at pH 5.0 produced an excellent separation of the two proteins (Figure 11.4). 

Adsorption processes Adsorption separation Adsorption separations Adsorptive separation... 

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