Monolayer regions

Thus, for the monolayer region of coke concentration, the intrinsic rate of burning of slow coke is given by... 

Suppose we consider a surface consisting of a total of M adsorption sites, M, of which are filled with adsorbed molecules to a depth of one molecule. Thus the number of bare sites M0 is (M - M ). This situation is defined to be in equilibrium when the rate at which molecules attach to bare spots is the same as the rate at which they escape from monolayer regions. The rate of the adsorption process Ra is proportional to both the pressure and the number of available sites ... 

In this chapter, some useful measurement methods of the interfacial adsorption and interfacial reaction, which take place at the monolayer region of the liquid-liquid interface, are reviewed along with some essential examples. 

Model 1. It is convenient and sufficiently reliable in many applications to separate the Type II isotherm into two parts the region above point B or the multimolecular region, and the region below point B or the monolayer region. Cook and Pack (9) showed that an excellent representation of the region from point B to x = 1.0 may be obtained by representing f in Equation 6 by the relation... 

A BET plot of all the data at 77° is linear over a wide range, and least-squares analysis of all the experimental values in the monolayer region (0.025 < p/p0 < 0.20) yields values of vm = 0.336 cc. per gram and c = 131. While the c value is very close to that previously observed for krypton adsorption on this mica (5), the surface area is appreciably smaller. This decrease in vm has occurred progressively with time for all our ground mica samples, and at present we have no... 

As already noted, the detailed course of a physisoiption isotherm is dependent on the nature of the gas-solid system and the operational temperature. In view of the wide variation in adsorbent-adsorbate interaction energies discussed in Chapter 1, it is not surprising to find that the shape of the isotherm in the monolayer region is especially sensitive to any variation in the surface structure of the adsorbent. However, as already indicated in Chapter 4, the shape of the corresponding multilayer isotherm is much less dependent on the adsorbent structure. 

The values of a(BET) in Table 9.1 are the BET-nitrogen areas, which were derived from the linear regions of the BET plots, with the molecular area assumed to be 0.162 nm2. The values of a(ext) in Table 9.1 are obviously much smaller than the corresponding values of a(BET). The question naturally arises does the BET method provide a reliable assessment of the total area (i.e. internal plus the external area) The non-linear character of the low-pressure region of each as-pk>t is a clear indication that the isotherm is distorted in the monolayer region and we may therefore conclude that a(BET) does not represent a real surface area. Additional support for this interpretation comes from the microcalorimetric data, which are discussed later in this section. More detailed discussion of some of the results in Table 9.1 is given in Chapter 12. 

In the case of liquid films three surfaces of tension could be recognised. One of them is inside the film and the tension of the film y, expressed by the known Bakker s integral, refers to it. Since the main contribution to yis related to the monolayer regions at the surfaces of the film yean be split into two parts... 

As seen from Fig. 5.25, in the initial monolayer region, calculated and simulated transients follow the quadratic law given by the pre-exponential term of eq. (5.15). In the further course of the transients, the theoretical curves go slightly astray. This is obviously connected with the different approximations used in the calculation of the contribution of the (n + l)th layer on top of the th layer. The most reliable results seem to be obtained by nucleation and disk growth Monte Carlo simulations (circles in Fig. 5.25) [5.43, 5.44]. 

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