Adsorption schematic

In Fig. 1.25 the one-dimension potential enthalpy diagram for physical adsorption (dotted line) and for associative (dot-dashed line) and dissociative (solid line) chemical adsorption schematically illustrates the features of the interactions described... 

Fig. XVII-5. Schematic detector response in a determination of nitrogen adsorption and desorption. A flow of He and N2 is passed through the sample until the detector reading is constant the sample is then cooled in a liquid nitrogen bath. For desorption, the bath is removed. (From Ref. 28. Reprinted with permission from John Wiley Sons, copyright 1995.)...

A second general type of procedure, due to McBain [29], is to determine n by a direct weighing of the amount of adsorption. McBain used a delicte quartz spiral spring, but modem equipment generally makes use of a microbalance or a transducer. An illustrative schematic is shown in Fig. XVII-6. 

Fig. XVn-6. Schematic of gravimetric apparatus for adsorption measurements. (From Ref. 30. Reprinted with permission from American Chemical Society, copyright 1995.)...

Fig. XVIII-22. Schematic illustration of the steps that may be involved in a surface-mediated reaction initial adsorption, subsequent thermalization, diffusion and surface reaction, and desorption. (From Ref. 199 copyright 1984 by the AAAS.)...

Figure Al.7.9. Schematic diagram illustrating three types of adsorption sites.

Fig. 2.27 Effect of mesoporosily on the adsorption isotherm and the t- (or a,-) plot, (a) (A) is the isotherm on a nonporous sample of the adsorbent (B) is the isotherm on the same solid when mesopores have been introduced into it, (i) being the adsorption, and (ii) the desorption branch. (b) I- (or a,-) plots corresponding to the isotherms in (a) (Schematic only.)...

Schematic diagram of a purge-and-trap system. Anaiyte is coiiected in the primary adsorption trap. The secondary adsorption trap is monitored for evidence of breakthrough.

Example of copredpitation (a) schematic of a chemically adsorbed inclusion or a physically adsorbed occlusion in a crystal lattice, where C and A represent the cation-anion pair comprising the analyte and the precipitant, and 0 is the impurity (b) schematic of an occlusion by entrapment of supernatant solution (c) surface adsorption of excess C. 

Schematics showing the basis of separation in (a) adsorption chromatography, (b) partition chromatography, (c) ion-exchange chromatography, (d) size-exciusion chromatography, and (e) eiectrophoresis. For the separations in (a), (b), and (d) the soiute represented by the soiid circie ( ) is the more strongiy retained.

Schematic diagram showing the development of a dipolar field and ionization on the surface of a metal filament, (a) As a neutral atom or molecule approaches the surface of the metal, the negative electrons and positive nuclei of the neutral and metal attract each other, causing dipoles to be set up in each, (b) When the neutral particle reaches the surface, it is attracted there by the dipolar field with an energy Q,. (c) If the values of 1 and <() are opposite, an electron can leave the neutral completely and produce an ion on the surface, and the heat of adsorption becomes Q,. Similarly, an ion alighting on the surface can produce a neutral, depending on the values of I and <(), On a hot filament the relative numbers of ions and neutrals that desorb are given by Equation 7.1,which includes the difference, I - <(), and the temperature, T,...

Molecular sieves are typically regenerated using a sHp stream of the treated gas at elevated temperature and reduced pressure. This regeneration step creates an enriched hydrogen sulfide stream which must then be further treated if the sulfur is to be recovered. A typical molecular sieve adsorption unit is shown schematically in Figure 2. 

FIG. 19-66 Schematics of (a) collector adsorption at the particle-water interface and (h) action of the frother. 

Fig, 29-13, Adsorption system shown schematically in Fig. 29-13. Source The British Ceca Company, Ltd. 

The above discussion has tacitly assumed that it is only molecular interactions which lead to adhesion, and these have been assumed to occur across relatively smooth interfaces between materials in intimate contact. As described in typical textbooks, however, there are a number of disparate mechanisms that may be responsible for adhesion [9-11,32]. The list includes (1) the adsorption mechanism (2) the diffusion mechanism (3) the mechanical interlocking mechanism and (4) the electrostatic mechanism. These are pictured schematically in Fig. 6 and described briefly below, because the various semi-empirical prediction schemes apply differently depending on which mechanisms are relevant in a given case. Any given real case often entails a combination of mechanisms. 

FIG. 1 Schematic picture of the graphite surface (C atoms occupy the corners, periodic boundary conditions apply in v and v directions) the adsorption sites in the y/3 X y/3 structure are shaded. 

FIG. 5 Schematic representation of adsorption isotherms in the region of the first-order phase transition on a homogeneous (solid line) and heterogeneous (filled circles) surface. 

Another special case of weak heterogeneity is found in the systems with stepped surfaces [97,142-145], shown schematically in Fig. 3. Assuming that each terrace has the lattice structure of the exposed crystal plane, the potential field experienced by the adsorbate atom changes periodically across the terrace but exhibits nonuniformities close to the terrace edges [146,147]. Thus, we have here another example of geometrically induced energetical heterogeneity. Adsorption on stepped surfaces has been studied experimentally [95,97,148] as well as with the help of both Monte Carlo [92-94,98,99,149-152] and molecular dynamics [153,154] computer simulation methods. 

In most cases surface reactions proceed according to well-established elementary steps, as schematized in Fig. 1. The first one comprises trapping, sticking, and adsorption. Gaseous reactants atoms and/or molecules are trapped by the potential well of the surface. This rather weak interaction is commonly considered as a physisorbed precursor state. Subsequently, species are promoted to the chemisorbed state, that is, a much stronger... 

Figure 9 The schematical representation of dispersion polymerization process, (a) initially homogeneous dispersion medium (b) particle formation and stabilizer adsorption onto the nucleated macroradicals (c) capturing of radicals generated in the continuous medium by the forming particles and monomer diffusion to the forming particles (d) polymerization within the monomer swollen latex particles, (e) latex particle stabilized by steric stabilizer and graft copolymer molecules (f) list of symbols.

FIGURE 2.23 Schematic diagram showing the routes of possible removal of drug from the receptor compartment. Upon diffusion into the compartment, the drug may be removed by passive adsorption en route. This will cause a constant decrease in the steady-state concentration of the drag at the site of the receptor until the adsorption process is saturated. 

Figure 2.5 N2 adsorption isotherms and schematized silicon dissolution (inset) upon alkaline treatment ofZSM-5 zeolites with different framework Si/AI ratios, highlighting the crucial role of framework aluminum.

FIG. 9 Schematic illustration of adsorption of poly(styrenesulfonate) on an oppositely charged surface. For an amphiphile surface in pure water or in simple electrolyte solutions, dissociation of charged groups leads to buildup of a classical double layer, (a) In the initial stage of adsorption, the polymer forms stoichiometric ion pairs and the layer becomes electroneutral, (b) At higher polyion concentrations, a process of restructuring of the adsorbed polymer builds a new double layer by additional binding of the polymer. 

FIG. 5 Schematic of multilayer assembly by consecutive adsorption of polyanion and polycation. 

Draw a schematic molecular orbital diagram for the adsorption of a diatomic molecule on a d metal. 

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