Formation of an adsorption layer

The energetics in the formation of a superstructure of a surface layer can be understood from FIM studies. A correlation between adatom-adatom interaction and the atomic structure of an adsorption layer has 

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Thus, the time that is necessary to attain a certain coverage, 6, or the time necessary to cover the surface completely (9 = 1) is inversely proportional to the square of the bulk concentration (cf. Fig. 4.10b). Assuming molecular diffusion only, 8 is of the order of 2 minutes for a concentration of 10 5 M adsorbate when the diffusion coefficient D is 10 5 cm2 s1 and rmax = 4 1010 mol cm 2 1). Considering that transport to the surface is usually by turbulent diffusion, such a calculation illustrates that the formation of an adsorption layer is relatively rapid at concentrations above 10 6 M. But it can become slow at concentrations lower than 10 6 M. 

In some cases it has been found that the maximum on saturation adsorption of a solute from a solution corresponds to the formation of an adsorption layer one molecule thick. Thus Euler Zeit. Elehtrochem. xxviii. 446,1922) found that a maximum adsorption of silver ions by silver and gold leaf was attained in a 0 03 A solution. It was found that 5 5 and 8 5 to 9 mgm. of silver ions were adsorbed by a square metre of metallic silver and gold respectively, such a surface concentration is practically unimolecular. The adsorption of silver ions by silver bromide (K. Fajans, Zeit Phys. Ohem. cv. 256, 1928) was found on the other hand to be not complete, for only every fourth bromide ion in a silver bromide surface was found to adsorb a silver ion. Similar conclusions as to the unimolecular character of the adsorbed film in the case of chemical charcoal as an adsorbing agent for fatty and amino acids may be drawn from the data of Foder and Schonfeld Koll. Zeit xxxi. 76, 1922). 

As already reported by several authors, the addition of carbon nanotubes did not affect the storage modulus in the glassy region, nevertheless a strong increase with the filler content is observed in the rubbery region. In conventional composites, this increase is mainly attributed to interfacial interactions leading to introduction of additional cross-links into the network by the filler. These interfacial interactions contribute to the formation of an adsorption layer whose thickness has been estimated around 2 or 3 nm and where... 

When solid particles are dispersed in liquid medium, solid-liquid interfacial interactions will cause the formation of an adsorption layer, the so-called lyosphere, on their surface. The material content of the adsorption layer is the adsorption capacity of the solid particle, which may be determined in binary mixtures if the adsorption excess isotherm is known [45-50], Due to adsorption, the initial composition of the liquid mixture, x°, changes to the equilibrium concentration Xi. This change, x - Xi = Axi, can be determined by simple analytical methods. The relationship between the reduced adsorption excess amount calculated from... 

When a solid adsorbent is immersed in a liquid mixture, the amount of which is + 2, the interfacial forces of adsorption cause the formation of an adsorption layer on the surface of the adsorbent, the material content of which is n = n + n. ... 

According to Everett s adsorption layer model [5,34,35], the heat of immersional wetting (A /f ), a thermodynamic parameter characteristic of the sohd-liquid interaction, can be easily calculated when the molar enthalpies of the components h- and h2 of the system are known. When a solid adsorbent is immersed in a liquid mixture, the amoimt of which is n + n . the interfacial forces of adsorption cause the formation of an adsorption layer on the surface of the adsorbent, the material content of which is = n] + 2-... 

The formation of an adsorption layer on the metal powder, introduced later into the powder electrode, has little or no influence on the obtained potential value, or, in some cases, it has only a considerably insignificant influence. The facts can be easily explained when it is pointed out that, as far as the first kind of powder electrode is concerned, its potential in relation to... 

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