Journal of Physical Chemistry, Vol.100, No.30, 12503-12508, 1996
Transport of Ions Through Cylindrical Ion-Selective Membranes
The rate of transport of ions through an ion-penetrable cylindrical membrane bearing negative fixed charges is investigated theoretically. For the same available space, the present novel device is capable of providing more surface area for ion transport than the conventional planar membranes through an array of hollow fibers type of apparatus. We consider a general linear distribution for the fixed charges in the membrane phase. A perturbation method is adopted for the resolution of the governing Nernst-Planck equation. The result of numerical simulation reveals that if the fixed charges are uniformly distributed, the current efficiency eta is independent of both the inner radius (or the curvature) of the membrane and the current density. We show that if the parameters of a membrane are chosen adequately, the value of eta can be increased by increasing the degree of nonuniformity of the fixed charge distribution under a constant amount of fixed charges.