Ionic strength, surface area function

FIGURE 15.10 Plots of the Gibbs free energy per unit area, AG/A, as a function of the distance between two oppositely charged planar surfaces, L, with the ionic strength as a parameter. The curves are calculated from Equation 15.63 with e=80, c =-0.16C/m, and Op = 0.03C/m. ... 

These synthetic hydrophilic polymers hydrophobically modified can be good systems with which to try to establish relationships between chemical structure and interfacial characteristics. It was determined the surface pressure - area (tt - A) isotherms at the air - water interface for poly(4-vinylpyridine) quaternized as a function of the methylene group number of the alkyl lateral chains (n). The film formation of these polymers on aqueous subphase at constant pH and ionic strength... 

Figures 9 and 10 show the fat surface area and the relative width of the globule size distribution, respectively, of all the protein stabilized emulsions as a function of the number of passes at a power consumption of 40 W (11). As can be seen from Figures 9 and 10 an increase in number o7 passes does not noticably enhance the final fat surface area of the protein stabilized emulsions, but affects more the distribution width by a decrease and a final level off. The caseinates at both ionic strengths produce emulsions of the smallest surface area and the narrowest distribution widths. The WPC stabilized emulsions have larger surface areas and wider spread in globule size than emulsions stabilized...

Figure 9.8. Surface charge as a function of pH and ionic strength (1 1 electrolyte) for a 90 mg liter" (TOTFe = 10" M) suspension of hydrous ferric oxide. The specific surface area is 600 g" and the site concentration is 2 x 10" mol sites per liter. (From Dzombak and Morel, 1990.)...

Adsorption of NOM onto activated carbon has been found to be influenced by a number of physicochemical properties such as e.g. pH value, NOM initial concentration, type and molecular size distribution of NOM, ionic strength, and water temperature (Lee et al., 1981 Cornel et al., 1986 Fettig and Sontheimer, 1987 Summers and Roberts, 1988 Johannsen et al., 1991 Kilduff et al., 1996 Bjelopavlic et al., 1999). Besides physicochemical characteristics of the process water adsorption is also dependent on properties of the activated carbon as e.g. pore volume, pore size distribution (Lee et al., 1981 Bjelopavlic et al., 1999 Ebie et al., 2001) surface area accessible for adsorption and surface functional groups as e.g. carboxyl, hydroxyl and carbonyl groups (Cookson, 1980). Adsorption of organic micro-pollutants is also affected by water and activated carbon properties. 

Figure 5.5 Uptake of [Ni(CN4) ] ions on BV46-S at pH 7 (squares), Ni + ions on BV46 at pH 6 (triangles), Cr + ions on BV46 at pH 6 (asterisks), and [Cr(C204) ] ions on HSl at pH 7 (diamonds) as a function of ionic strength. Sample BV46 is an activated carbon from olive stones. Oxidation of this sample with (NH4)2S20s yielded sample BV46-S. Sample HSl was a low-surface-area oxidized active carbon. (From ref. 26, with permission.)...

Mobile phase parameters that have to be optimized include the salt type, concentration, gradient shape, pH, temperature, and possibly the addition of a surfactant or organic solvent [368-372]. The change in free energy on protein binding to the stationary phase is determined mainly by the contact surface area between the protein and stationary phase and by the salt type determined by its ability to increase the surface tension of aqueous solutions. Solvophobic theory predicts that in the absence of specific salt-protein interactions and at sufficient ionic strength the logarithm of the retention factor is linearly dependent on the surface tension of the mobile phase, which in turn, is a linear function of the salt concentration Eq. (4.13)... 

The kinetics of chemical reactions can provide many clues as to the nature of the bond-breaking and bond-making processes on the molecular level that lie at the core of any reaction mechanism. The reaction rate can be defined as the differential rate of loss of a reactant or the differential rate of formation of a product as a function of time. The rates of chemical reactions depend on a variety of factors, including the concentrations of the reactants, ionic strength, temperature, surface area, and... 

Figure 20.8. The double-layer free energy of interaction per unit area between two flat surfaces as a function of surface separation in an aqueous solution of ImM ionic strength. One of the surfaces has a surface charge density of 1 mClvsr, whereas the surface charge density of the other surface is 1 mC/m ( ), 0.5 mC/m ( ) and zero (A)...

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