Anion permeation behavior of polypyrrole/regenerated cellulose composite membranes under applied potential

Composite membranes were prepared by combination of polypyrrole and a porous material of regenerated cellulose, and the permeation characteristics of a variety of anion species through the composite membranes were investigated under different potentials applied. The composite membranes work effectively as a functional membrane to control the permeation flux of anions by application of a potential. The anion permeation flux increases constantly as the potential is raised, except for the anions with extremely low molecular weight. This is explained by a permeation model in which the ion-exchanging migration of the anions through the positive sites of the polypyrrole layer contributes largely to their permeation. The main factors dominating the permeation characteristics are the molecular weight of the anions and the morphology of the polypyrrole layer. Permselectivity, i. e., separation of specific anions with a certain molecular weight, is expected for the composite membranes.