Adsorption time and

Adsorption Kinetics. Figure 1 shows the adsorbance, Ap, of NaPSS-3 as a function of adsorption time for two NaCl concentrations at the NaPSS concentration of 0.04 g/lOOml. Hie Ap first increases with adsorption time and then the equilibrium adsorbance is attained after 1.5 x 10J minutes. 

The thickness, t, of the adsorbed layer for NaPSS-3 is plotted against adsorption time as shown in Figure 2. Hie t also increases with increasing adsorption time and becomes a constant value. Similar time dependence was obtained in the other experiments. Therefore, both Ap and t determined after 1.5 x 103 minutes were taken as the equilibrium values. 

The binding energy in field adsorption can be derived from consideration of the kinetics of field adsorption. Specifically, it can be determined from a temperature dependence of the probability of field adsorption on an adsorption site, or the degree of coverage of field adsorption on a plane. As will be shown, a consideration of the probability of field adsorption based on adsorption time and desorption time leads to an equation equivalent to the Langmuir adsorption isotherm, but specific to the problem of field adsorption.112115 Let us focus on one surface atom. The average time it takes to have an image gas atom field adsorbed on the surface atom, ra, is... 

The approach of Prasad and Huntress (1980a, b) might be called the chemical time dependent approach because it utilizes fixed physical conditions. However, the chemical evolution to steady-state takes so long that it may be unwise to maintain fixed physical conditions. Time scales more rapid that the 107 years needed to reach chemical steady-state include the grain adsorption time and the free-fall collapse time. Thus, in the simplest approximation, chemical steady-state can never be reached because the gas phase will be adsorbed into the grains and the cloud will have collapsed to form, presumably, a star. The observed facts that clouds do not form stars as rapidly as the free fall model and that they do possess a gas phase, both demonstrate that... 

Study of the V-typc sample (Table 2) has shown that D, D2, and D3 doses inhibit cell growth by 9.7, 18.6, and 24.2%, respectively. This is close to the effect of Platidiam Ptd-L solution from which the drug adsorption was carried out. Results obtained show that almost all Platidiam is released from the magnetically sensitive carrier into the cultivated medium. Increased cytostatic action of magnetically sensitive nanocomposites (Platidiam carriers) may be achieved by means of solvent, adsorption time, and temperature optimization. 

Figure 10. The properties of films generated by an ETES polymer-monomer solution on air-dried silica. The change in yr (A) and Oh o (B) adsorption time and the change in 0H9O (C) in the water desorption test (20 hrs. adsorption time)...

Aluminium Compound Adsorption time and temperature Solvent Cone, of ethyl groups (mole per mole TiCls)... 

In Figure 14.3c a normalization in a single master curve of E vs. tt data reflects the interfacial behavior of emulsifier adsorbed films for different emulsifier concentrations, at different adsorption times, and under different processing conditions (Nino and Patino, 2002 Nino et al., 2003). The plot suggests that interactions between adsorbed emulsifier molecules (residues) increase with tt. In fact, at lower tt values the slope of the -tt plot was close to 1, which corresponds to the behavior of an ideal gas with low emulsifier interactions. However, at higher tt values the slope changes, which implies an important nonideal behavior with higher molecular interactions as the amount of emulsifier at the interface increases. These data indicate that the interfacial activity and the surface dilatational modulus of emulsifier films are mainly a result of the amount of adsorbed emulsifier. 

A comparison of some experimental data, obtained from different techniques, is presented below. All data are shown as a function of the effective adsorption time and can therefore be interpreted by the theories elaborated for a standard situation, neglecting any liquid flow, surface area changes etc. 

The quantitative analysis of the adsorption mechanism (cf Miller Kretzschmar 1991) shows a diffusion controlled adsorption over the whole concentration range with a slight change of the diffusion coefficient D with adsorption time and surfactant concentration. A detailed data analysis with butyl phenols of different chemical structure is in progress. 

The flash filament experiment as first described by Becker and Hartman (14) has since been used extensively in studies of the adsorption of gases onto refractory metals, particularly in association with other techniques. The basic method is to allow gas introduced at a known input rate to adsorb for a measured time onto a previously cleaned wire or ribbon. The gas is then desorbed by heating the sample, and the resulting pressure bursts monitored. The pressure versus time curve is referred to as a desorption spectrum, as illustrated in Fig. 4 and 5. Sticking probabilities can then be obtained from the relative adsorption times and desorption quantities. Methods of analysis of these desorption spectra (15, 16) and of the variation in thermal resolution by different heating schedules such as linear or reciprocal increase in temperature with time, have been discussed extensively by a number of authors... 

A potential and concentration dependent adsorption was found in alkaline medium for all the species studied. Two types of adsorption were distinguished. During the first stage of the adsorption loosely adsorbed species are mainly formed, but with increasing adsorption times and concentrations the role of a strongly chemisorbed species becomes much more pronounced. 

Now the number of effects is large enough to justify drawing a normal plot (Fig. 3A.6). The adsorption time and feeding flow rate (4 and 3, respectively) are the most significant main effects, followed, at a certain distance, by their interaction effect and the adsorption pressure main... 

Adsorption of thiolated probes was studied, in this sense adsorption time and probe concentration were tested. Results obtained shown that 20 minutes was enough time to reach a plateau in the anal3ftical signal, and probe concentration was fixed in 10 nM, because higher concentrations resulted in a decrease in the anal)ftical signal. 

Various aspects of SAM formation, structure, properties, and possible applications are discussed in other chapters. The properties of a SAM of a certain composition depend on a number of parameters, such as the solvent used for self-assembly, the concentration of the adsorbing molecules, the adsorption time and temperature, and to an appreciable degree, on the properties of the substrate. The latter include the substrate type, chemical composition, morphology, preparation, pretreatment, and cleanliness. 

Colloidal gradients were prepared by successively exposing a surface to a colloidal suspension with known properties for a specific time interval. If the surface and the particles interact electrostatically, particles will start to adsorb and form an incomplete particle layer, the number adsorbed depending on the time for which the particles were allowed to adsorb. This process is sketched in Figure 2, which (a) shows the situation after short adsorption times and (b) represents the jamming limit of the monolayer (which is reached after a longer time interval, depending on particle concentration). 

A particularly strong advantage of the BAM method is that it can be used to directly image monolayers formed by adsorption from the subphase. Phase transitions as a function of surface coverage, related to the subphase concentration, adsorption time, and temperature can be observed for such adsorbed monolayers. In one series of studies, the... 

In accordance with the reversibility of the colloidal properties of thermally sensitive particles, the adsorption of proteins is also found to be reversible in the same cases. In fact, 90% of adsorbed protein can be desorbed just by lowering the temperature (i.e., from above to below the volume phase transition temperature). The hydration processes of the particles lead to a reduction in adsorption affinity, which favors the desorption process (see Figure 9.27). Furthermore, the desorbed amount of protein can be inaeased by reducing the adsorption affinity through changing the pH and salinity levels. The residual adsorbed (or the non-total desorption) amount is closely related to the adsorption time and to the protein nature. In fact, the more the incubation time (above the Typr) is increased, the more the desorbed amount (below the vpt) is reduced. 

Basic properties were also measured by TPD of probe molecules such as CO2, CO and H2. Although CO2 appears to be the proper probe molecule because of its acidic nature, TPD profile of CO2 varies depending on the adsorption condition of COi Only a broad desorption peak appeared if too much CO2 was adsorbed. The alkaline earth oxide surfaces react with CO2 to form different surface structures depending on the adsorption time and temperature. TPD profiles of adsorbed CO2 on MgO, CaO, SrO, and BaO measured under controlled adsorption conditions are shown in Fig.2.9. >... 

Although SP-A is important for the formation of tubular myelin, it is not essential for the formation of the surface film at the air-liquid interfaee. Other surfactant materials (i.e., SP-B or SP-C-lipid mixtures) ean generate surfaetant films at the air-liquid interface, with rapid adsorption times and high surfaee pressures (low surface tension) that closely resemble the characteristics of natural pulmonary surfactant (39). 

---