Water transport in a non-aqueous, polypyrrole electrochemical cell

A conducting polymer based liquid membrane electrochemical cell is presented in which reversible water transport in propylene carbonate (PC) is achieved by applying a dc voltage across the cell. In a cell two electrochemically deposited polypyrrole (PPy) films are utilized together with a porous separator filled with an electrolyte solution to make a sandwich structure, and the water vapor pressure adjacent to each electrode is measured. Under a cycling electrode potential the movement of solvated ions across the cell reversibly transports water. PPy films with different dopant anions (BF4−, PF6−, DBS−) are tested in PC solutions containing corresponding anions and different cations (Li+, Na+, TBA+). Water activity increases at the cathode and decreases at the anode. Water transport numbers for different liquid membrane systems are estimated and discussed.