Abstract
In this study, fundamental aspects of permeation phenomena through charged membrane were discussed. Permeation behavior of particles through membranes is principally influenced by the poresize of the membrane and the size of permeating particles. If there are fixed charges within the membrane phase, the electrostatic interaction between the particles and the fixed ionic groups should also be considered. The discussion mentioned above follows the gradient of electrochemical potential of permeating particles based on equilibrium thermodynamics or the phenomenological equation based on non-equilibrium thermodynamics. Measurement of membrane potential is an effective method for observing the movement of ions permeating through it or the interaction with the fixed charge within it, by which data permselectivity of ions could be explained.
Along with the properties cited above, some applications of charged membranes, including reverse osmosis (RO), pressure retarded osmosis (PRO), polymer electrolyte fuel cell (PEFC) and iontophoresis, were explained. By considering the ionic interactions between particles and fixed charges within the active layer of the RO-membrane, the production of purified water by the RO process should become more effective. We can change osmotic power into electricity based on PRO. Although the PRO process now uses existing membranes for the RO process, a newly developed membrane fitting the process is required. If charged membranes made of hydrocarbon are used for PEFC, the newly installed system to provide electricity would be more effective and more ecologically friendly. Iontophoresis is a relatively new application using charged membranes. It is a non-invasive method for transdermal drug delivery that can give us safer medical treatments. At last, charged membranes will be a key factor for the sustainable future of our society.
