Effects of electrolyte concentration

Fig. VI-5. The effect of electrolyte concentration on the interaction potential energy between two spheres where K is k in cm". (From Ref. 44.)...

For example, van den Tempel [35] reports the results shown in Fig. XIV-9 on the effect of electrolyte concentration on flocculation rates of an O/W emulsion. Note that d ln)ldt (equal to k in the simple theory) increases rapidly with ionic strength, presumably due to the decrease in double-layer half-thickness and perhaps also due to some Stem layer adsorption of positive ions. The preexponential factor in Eq. XIV-7, ko = (8kr/3 ), should have the value of about 10 " cm, but at low electrolyte concentration, the values in the figure are smaller by tenfold or a hundredfold. This reduction may be qualitatively ascribed to charged repulsion. 

Table II also shows the effect of electrolyte concentration on Rf and kj. Both effects reflect the fact that at the higher ionic strengths particle/substrate repulsion is decreased, thus effectively increasing the available pore volume at a given particle size. These results are illustrated in Figure 3. Included in this figure are data from work by Nagy (14) with a column set similar in configuration to that employed here.

In a study of the effect of electrolyte concentration on gas holdup, Bly and Worden (1990) found a strong effect. A salt solution resulted in twice the gas holdup that distilled water did under otherwise identical operating conditions, because the salt solution suppressed bubble coalescence. Investigation of this phenomenon is important in biofluidization, because biological media commonly have high electrolyte concentrations. 

As a final topic in this section, we briefly consider the effect of electrolyte concentration on the solvent properties. The linearized Poisson-Boltzmann equation [31,121] can be used instead of (2) and (3) when the dielectric medium... 

The effects of electrolyte concentration and valence in this approximation are qualitatively consistent with the results of more elaborate calculations. 

Of the various quantities that affect the shape of the net interaction potential curve, none is as accessible to empirical adjustment as k. This quantity depends on both the concentration and valence of the indifferent electrolyte, as shown by Equation (11.41). For the present we examine only the consequences of concentration changes on the total potential energy curve. We consider the valence of electrolytes in the following section. To consider the effect of electrolyte concentration on the potential energy of interaction, it is best to use the more elaborate expressions for interacting spheres. Figure 13.8 is a plot of ne, for this situation as a function of separation of surfaces with k as the parameter that varies from one curve to another. 

Here, the association constant KA can be determined by measuring the conductivity of the unsaturated solutions. Corrections are made by successive approximations for the effect of electrolyte concentrations on molar conductivity A and for the effect of activity coefficient on KA. Here, k/Ar% is used as the first approximation of the ionic strength. 

Primary sail effects refer to the effects of electrolyte concentration on the activity coefficients. Secondary salt effects are those concerned with the actual chances in concentration of the reacting species resulting from the addition of electrolytes. 

Tombacz, E., Gilde, M., Abraham, I. and Szanto, F. (1988). Effect of electrolyte concentration on the interaction of humic acid and humate with montmorillonite, Appl. Clay Sci. 3, 31-52. 

The effect of electrolyte concentration on the transition from common to Newton black films and the stability of both types of films are explained using a model in which the interaction energy for films with planar interfaces is obtained by adding to the classical DLVO forces the hydration force. The theory takes into account the reassociation of the charges of the interface with the counterions as the electrolyte concentration increases and their replacements by ion pairs. This affects both the double layer repulsion, because the charge on the interface is decreased, and the hydration repulsion, because the ion pair density is increased by increasing the ionic strength. The theory also accounts for the thermal fluctuations of the two interfaces. Each of the two interfaces is considered as formed of small planar surfaces with a Boltzmannian distribution of the interdistances across the liquid film. The area of the small planar surfaces is calculated on the basis of a harmonic approximation of the interaction potential. It is shown that the fluctuations decrease the stability of both kinds of black films. 

The effect of electrolyte concentration on double-layer interaction... 

Figure 9.12. Effect of electrolyte concentration (NaHCOs) on dispersibility and the determination of critical salt concentration (from Arora and Coleman, 1979, with permission).

Agassi, M., 1. Shainberg, and J. Morin. 1981. The effect of electrolyte concentration and soil sodicity on infiltration and crust formation. Soil Sci. Soc. Am. J. 45 848-851,... 

Gardner, W. R., M. S. Mayhugh, J. O. Goertzen, and C. A. Bower. 1959. Effect of electrolyte concentration and exchangeable sodium percentage on diffusivity of water in soils. Soil Sci. 88 270-274,... 

Figure 4 Effect of electrolyte concentration on electroosmotic mobility in open tube (upper) and in packed column (lower). (Reprinted with permission from Ref. 21, copyright 1997, with permission from Elsevier Science.)...

The mean ion activity coefficient values can be obtained from experiments where the effect of electrolyte concentration on the A sp value for a salt is determined. The mean values are then compared with those for KCl under the same solution conditions. The single-ion activity coefficient for Ca " " can then be computed if an assumption is made about the individual values for and Cl. These ions have the same magnitude of charge and similar electronic configuration, ionic radii, and ionic mobilities. On the basis of these properties, the Macinnes convention (1919) states that... 

FIGURE 8-8 Schematic diagram of potential as a function of distance from a charged surface A, effect of surface charge B, effect of electrolyte concentration (Cl > Cl > C3) C, effect of charge of counterion (Zi < Z2 < Z3). 

FIGURE 15.4 The effect of electrolyte concentration on the viscosity of 13.2% A90 silica at pH as a function of shear rate. 

Figure 10-1 Effect of electrolyte concentration on concentration-based equilibrium constants.

Figure 10-2 Effect of electrolyte concentration on the solubility of some salts.

The effects of electrolyte concentration. Okazaki et al. [26] reported no effect of electrolyte concentration on adsorption of copper and zinc by iron and aluminium oxides. Similarly, from their own work, and from a survey of the literature, Hayes and Leckie [27] concluded that there was little effect of electrolyte concentration on metal adsorption. However, a wider view of the literature shows that there are indeed effects on surfaces which are probably negatively charged - for example, for adsorption of nickel on kaolinite [31], for zinc on soil [32], for copper, cadmium and lead on kaolinite [33] and for cadmium on soil [34]. This discrepancy probably arises because metal adsorption on oxides often... 

The effects of electrolyte concentration. The effects of electrolyte concentration on anion reaction depend on the pH and thus on the charge carried by the surface. At sufficiently low pH, increasing electrolyte concentration decreases adsorption. At a higher pH, it increases it (Fig. 5). There is thus a pH at which electrolyte concentration has little effect. For anions, this point of zero salt effect occurs at a lower pH than the point of zero charge of the oxide. For the data in Fig 5., the point of zero salt effect on phosphate adsorption was just above pH 4, whereas the pzc of the non phosphated oxide was near pH 8. That is, reaction with the anion has decreased the charge on the oxide. 

The efifect of electrocatalyst and operating conditions on selectivity were examined recently for the reduction of olefinic halides to saturated halides or cleavage products (hydrogenation versus hydrogenolysis) 31. These two steps proceed in parallel at different rates on various electrocatalysts. Thus, the ability for double bond reduction decreases in the order Pd Ru > Ag > Pt, although the overall rate is about the same on Pd and Pt (cf. Table VI). Figure 24 shows the extensive variation of reaction specificity with cathode potential as well as the smaller effect of electrolyte concentration. Similar behavior is exhibited by other halides and electrodes 31. ... 

FIGURE 12.24 Effects of electrolyte concentration [NaCl] on modified HIV-1 capsid P24 protein adsorption onto cationic thermally sensitive core-shell microspheres at 40°C, pH 6.1 at 20°C ( ) and 40°C ( ). (Adapted from Duracher, D., Ph.D., thesis, 1999.)... 

---