Membrane transport in the presence of an applied electrical potential gradient parallel to the aqueous ∣ membrane interface

When a membrane system composed of two aqueous phases (W1 and W2) separated by a liquid membrane (M) was adopted, and potential difference, EM(A–B), was applied between two sites (sites A and B) in M, the ion transport reaction from M at site A to M at site B through W1 or W2 (M–W1–M or M–W2–M transport) was found to occur based on the voltammogram recorded by scanning EM(A–B) and measuring the current between sites A and B. The efficiency of M–W1–M or M–W2–M transport was higher when the ratio of the concentration of electrolyte in M to that in W1 or W2 was lower. An ion transfer reaction at the W1 ∣ M or W2 ∣ M interface in a region between sites A and B (site C) could be realized under the application of EM(A–B). The ion transport from W1 to W2 through a special region of M was also found to be possible under the applied EM(A–B). Similar ion transport from W1 to W2 occurred even when the EM(A–B) was applied by using chemical reactions instead of an external circuit.