Mass transport investigated with the electrochemical and electrogravimetric impedance techniques .2. Anion and water transport in PMPy and PPy films

Water transport during anion transport in poly(N-methylpyrrole/nitrate) (PMPy/NO3), poly(N-methylpyrrole/chloride) (PMPy/Cl), and poly(N-methylpyrrole/sulfate) (PMPY/SO4) films, where ion transport is anion-specific, has been investigated by comparing electrical responses with gravimetric responses in the cyclic electrochemical quartz crystal microbalance (EQCM) experiment and the impedance experiment. It is shown that the number of accompanying waters per Cl- or SO42- is considerable, whereas the number per NO3- is nor large. The number of accompanying waters per anion does not change extensively with the concentration of an electrolyte solution and the applied potential. Moreover, the possibilities of OH-, H+, cation, and water transport in poly(pyrrole/nitrate) (PPy/NO3) and poly(pyrrole/chloride) (PPy/Cl) films, where ion transport is not anion-specific, have also been investigated. It is found that OH- moves competitively with NO3- or Cl- during their redox reaction.