Migration, Effect

Increased variable Effect onHj availability Effect on migration Effect on isomerization... 

An example of the determination of activation enthalpies is shown in Figs. 11 and 12. A valuable indication for associating the correct minimum with the ionic conductivity is the migration effect of the minimum with the temperature (Fig. 11) and the linear dependence in the cr(T versus 1/T plot (Fig. 12). However, the linearity may be disturbed by phase transitions, crystallization processes, chemical reactions with the electrodes, or the influence of the electronic leads. 

Densification is also influenced by the presence of supporting electrolyte. As shown in the last line of Table II, the relative densification in acidified cupric sulfate is less than that in binary cupric sulfate solution. In the case of the supported redox reaction, that is, in the presence of KOH or NaOH, the migration effect makes the density difference larger than that expected from overall reaction stoichiometry. 

Fig. 14. Integral diffusivities of Cu2 +, corrected for migration effect, as a function of true ionic strength, /r. Circles and triangles indicate values reported by Selman (S8) and Hsueh (H7), squares indicate results of Arvia el al. (A5). Diaphragm cell diffusivities according to Fenech (F3) and capillary cell diffusivities according to Hsueh (H7) are also shown. [From Selman (S8).]...

The contribution of transport under the influence of the electric field (migration), which, if appreciable, should be subtracted from the total mass flux. The use of excess inert (supporting) electrolyte is recommended to suppress migration effects. However, it should be remembered that this changes the composition of the electrolyte solution at the electrode surface. This is particularly critical in the interpretation of free-convection results, where the interfacial concentration of the inert as well as the reacting ions determines the driving force for fluid motion. 

Factors Affecting Ionic Migration. Effect of Temperature. pH and Ionic Strength. Electro-osmosis. Supporting Medium. Detection of Separated Components. Applications of Traditional Zone Electrophoresis. High-performance Capillary Electrophoresis. Capillary Electrochromatography. Applications of Capillary El ectrochromatography. ... 

For medium integration time the time-bandwidth product is limited by the range migration effect [40] ... 

Turning back to field effects, they derive from the second terms on the right-hand sides of equations (4.22), (4.23), (4.25), and (4.26). It should be noted that they are different from the corresponding term in the Nernst-Planck equation, which depicts migration effects for free-moving ions as recalled in... 

Yong RN, Warith MA (1990) Contaminant migration effect on dispersion coefficients. ASTM.STP 1095 69... 

Having an excess of unreactive electrolyte induces the phenomenon of electrode polarization, with a buildup of oppositely charged electrolyte ions at the electrode solution interface. Such polarization decreases and hence suppresses all migration effects. The most commonly used salts for the purpose of suppressing migration in water are KCl and KNO3. 

In Chapter 3, we looked at the way the activity coefficients can be more or less equalized if there is a swamping electrolyte in solution (see Section 3.4.4, SAQ 3.9 and Figure 3.8). By the nature of the species studied in a chronoamperometric experiment, (a) a swamping electrolyte is added to the solution in order to minimize migration effects, and... 

Swamping electrolyte An ionic salt added to a solution of analyte in order to minimize migration effects and increase the ionic conductivity. 

The elution and migration effects are also found in PDC, but not the compression effect, since no precipitant and temperature gradients are applied. Unlike BWF, no simple transport Equation is applied in PDC because the replacement of the linear Eq. (3b) by the non-linear (17c) would lead to an integrodifferential equation similar to (41 a-b), but more complicated, if some explicit formulation were used instead of the implicit one, based on a flow-equilibrium and on a perturbation calculus, applied to an integrated transport Equation... 

---