ON CURRENT DEPENDENCE OF THE ELECTROOSMOTIC PERMEABILITY IN ION-EXCHANGE MEMBRANES

The apparent electro-osmotic permeability, W, of three ion-exchange me mbranes has been obtained under different experimental conditions. The behaviour of W as a function of the current density, I, shows the fol lowing characteristics: (i) at sufficiently low values of I, the appar ent electro-osmotic permeability decreases when the current density in creases; (ii) at an intermediate values of I, a local maximum appears; and (iii) at the highest values of I, the apparent electro-osmotic pe rmeability seems to approach a roughly constant value. The value of I at which the local maximum takes place is very close to the so-called limiting current density.