Mixed electrolyte systems

Essentially, the new parameters B and 0 are binary ion-ion parameters and C and ternary ion-ion parameters. The ion-ion interaction parameters, B and C, are characteristic of each aqueous single-electrolyte system. The ion-ion difference parameters, 9 and, are characteristic of each aqueous mixed-electrolyte system. 

In addition, a model is needed that can describe the nonideality of a system containing molecular and ionic species. Freguia and Rochelle adopted the model developed by Chen et al. [AIChE J., 25, 820 (1979)] and later modified by Mock et al. [AIChE J., 32, 1655 (1986)] for mixed-electrolyte systems. The combination of the speciation set of reactions [Eqs. (14-74a) to (14-74e) and the nonideality model is capable of representing the solubility data, such as presented in Figs. 14-1 and 14-2, to good accuracy. In addition, the model accurately and correctly represents the actual species present in the aqueous phase, which is important for faithful description of the chemical kinetics and species mass transfer across the interface. Finally, the thermodynamic model facilitates accurate modeling of the heat effects, such as those discussed in Example 6. 

In many cases mixed electrolyte systems can he added to a latex either adventitiously or deliberately. Hieir effects on the stability of dispersions can best be summarized by Fig. 22. The axes of this figure are plotted as a percentage, so that the abscissa is the ccc value of salt 1 expressed as a percentage of its ccc value in the absence of the second salt salt 2 is expressed on a similar basis. Thus, the simplest possible case is additivity in... 

Electrolysis of solutions can be used for electrodeposition of a trace metal on an electrode. The selectivity and efficiency which would be present for electrolytic deposition of macro amounts of ions at a controlled potratial is not present, however, for trace amounts. The activity of trace amounts of the species is an unknown quantity even if the concentration is known, since the activity coefficient is dependent upon the behavior of the mixed electrolyte system. Moreover, the concentration of the tracer in solution may not be known accurately since there is always the possibility of some loss through adsorption, complex formation with impurities, etc. Nevertheless, despite these uncertainties it has been found that the Nemst equation can be used, with some caution, for calculating the conditions necessary for electrolytic deposition of trace metals. 

The convention has succeeded in yielding ionic activities that agree with observed values [34] and has also been extended with equal success to special cases of mixtures of two univalent electrolytes [35,36]. Of course, in practice, one of the attractive features of ion-selective electrodes is their ability to respond to the activity of one particular ion in the presence of others in mixed electrolyte systems, so that a knowledge of ion activities in mixtures is of some importance. Here, most interest has centred on mixed electrolyte solutions of biological significance [2,9,28,30,34—44], but whatever the stem, the primary concern is the variation in activity of one electrolyte in the presence of others. 

The separation of Tp into ratios for the solution and solid phases is useful when solution phase activity coefficients are available (5) because it allows evaluation of variations from ideality of the clay phase alone over a range of experimental conditions. When measurements for the aqueous mixed electrolyte systems in question are not available, adequate estimates can frequently be made by Debye-Huckel equations or by various methods from measurements on two-component systems (6). 

Let us consider the ion assignments made for single electrolytes in an effort to describe the behaviour of mixed electrolyte systems. Pairs of electrolytes can be categorised based on these assignments and they give rise... 

Also, as the ion partition coefficients apply to mixed electrolyte systems and the behavionr of mixed electrolyte systems is not predicted by measurements of the surface tension, we can state that the partitioning of the ions at the interface controls bubble coalescence through a mechanism other than the surface tension. 

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