|Title:||Current efficiency of ion-selective membranes: Effects of local electroneutrality and Donnan equilibrium||Authors:||Hsu J.-P.
|Issue Date:||1997||Journal Volume:||101||Journal Issue:||40||Start page/Pages:||7928-7932||Source:||Journal of Physical Chemistry B||Abstract:||
The current efficiency, E, of the transport of ions through an ion-penetrable, charged membrane is investigated. Two assumptions often made in the literature, namely, local electroneutrality and Donnan equilibrium, are discussed quantitatively. We show that, if the concentration of fixed charges, C3, is sufficiently high, the former is appropriate except for the region near the liquid-membrane interface. The deviation from local electroneutrality is alleviated if Donnan equilibrium can be assumed. In general, if C3 is low, the local electroneutrality is unsatisfactory. Typically, assuming local electroneutrality will overestimate E to an extent on the order of 10% for a high C3 and 30% for a low C3. If C3 is high, the effect of fixed charge distribution on E is marginal, regardless of whether Donnan equilibrium is satisfied. It is significant, however, for the case where C3 is low. For a fixed total amount of fixed charges, linear fixed charge distribution leads to a higher E than sinusoidal fixed charge distribution.
|Appears in Collections:||化學工程學系|
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.