Interfacial ion transfer

The voltammograms recorded for parallel transports of types I and II were very similar to those for perpendicular transport, and had characteristics which were described as (a), (b) and (c) in the previous section and expressed by Equations (35) and (36). The results indicate that the voltammograms were realized mainly by the composite of two interfacial ion transfer reactions, i.e., reactions at the Wl/M interface of sites A and B for parallel transport of type I and reactions at the W1/M and W2/M interfaces of sites A and B for parallel transport of type II. In other words, parallel transport of type I(W1->M->W1 transport) and parallel transport of type II (M->- W1 ->M or M-> W2-> M transport) could be realized when potential differences were applied between two sites in one aqueous phase of the system of Figure 6.7b and between two sites in the membrane of the system of Figure 6.7c, respectively. 

Attempts to extend the theory of charge transfer in polar media [106, 107] to ion transfer across a liquid-liquid interface were reviewed by Kunetsov and Kharkats [112]. The complexity of interfacial ion transfer follows from the fact that this is essentially a many-body problem, comprising motions of various components of the system interacting with each other which are difficult to separate. In particular, the... 

The values of diffusion coefficients and thermodynamic parameters on the interfacial ion transfer are determined and summarized in Tables 1 and 2. The diffusion coefficients of Na+ and K+ are of the values in the aqueous solutions of [MgS04] = 0.125 M and those of N15C5 are of ones in the NB and DCE solutions of [THATPB] = 0.10 and 0.010 M, respectively. The value of Na+ in NB is not evaluated because any clear polarographic wave has not been observed in the Na+ diffusion-control system. The values of K+ are... 

The transfer of amines [17-19] and weak acids [20,21] between the aqueous phase (W) and the organic phase (O) across the 0 W interface is a typical example of the ion transfer with preceding chemical reactions. In the case of the transfer of ammonium ions across the interface, the interfacial ion transfer ... 

Hydration phenomena of ions in organic solvents and their roles in interfacial ion-transfer processes have been extensively discussed for many years.. As discussed in this chapter, a marked development in this field may be recognized, at least from a thermodynamic viewpoint. However, no detailed molecular pictures of hydrated ions in organic solvent have been provided yet. Further experimental and theoretical approaches seem to be required. Vibrational spectroscopic and molecular dynamics simulation studies on solvation of ions in the gas phase [70,71] would shed light on the microscopic structure and dynamics of hydrated ions in organic solvents. 

There are three unknown quantities in equation (4.37) -/)(/), R t) and c, and to find them we need two other independent expressions for the growth current. Apparently the first one must be again the Faraday law (equation (4.32)) whereas the second must describe the interfacial ions transfer reaction according to (see e.g. [4.102] and [4.103]) ... 

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