Process of ion transport through a membrane

A quantitative understanding of the membrane transport is very important for elucidating physiological reactions occurring at biomembranes such as nervous transmission, respiration and metabolism as well as the application of the membrane transports to analytical methods such as liquid membrane type ion sensors and membrane separations [17-19]. 

FIGURE 6.5. Voltammograms for ion transfer from W1 to W2 through M (curve 1), at the WlfM interface (curve 2) and at the MAV2 interface (curve 3). See Equation (34) for compositions of Wl, M and W2. Scan rate of wi-w2. 0.01 V s .  

The final rise and the final descent in curve 3 correspond to the transfer of CV+ from M to W2 and that of TPhB from M to W2, respectively. 

Comparing curve 1 with curves 2 and 3, it is obvious that (a) the potential window in curve 1 is about twice that in curve 2 or 3, (b) the potential regions where the positive and the negative peaks appear in curve 1 are different from those in curve 2, and (c) the slopes of the positive peak, negative peak, final rise and final descent in curve 1 are much smaller than those in curves 2 and 3. 

In order to elucidate the reaction involved in curve 1, the relation among w i -W2 in curve 1, w I /M in curve 2 and m/w2 in curve 3 was investigated at a definite membrane current, /wi w2 inking into account that currents flowing across both the Wl/M and MAV2 interfaces must be the same and equal to the membrane current. The relation 

The group of the present author investigated the relation between the membrane potential (the potential difference between two aqueous solutions, W1 and W2, separated by a membrane) and the membrane current (the current flowing between W1 and W2), and obtained the voltammogram for the ion transfer through a membrane (VITTM). The membrane used was a liquid membrane, M. Then, the VITTM was compared with the voltammograms at the W1/M and M/W2 interfaces recorded simultaneously with the VITTM, and the membrane transport process was elucidated [20,21] as follows. 

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