Properties of ion exchange membranes

The most desired properties of ion-exchange membranes are high permselectivity, low electrical resistance, good mechanical and form stability, and high chemical and thermal stability. In addition to these properties bipolar membranes should have high catalytic water dissociation rates. 

Kunst B and Lovrecek B. Electrochemical properties of ion-exchange membrane junctions. Croat. Chem. Acta 1962 34 219-225. 

The electrical resistance of the membrane is an important property of ion-exchange membranes. The membrane resistance is determined by the lEC and the mobility of the ions within the membrane matrix. The electrical resistance is dependent on temperature and decreases with increasing temperature. 

Schlogl R. Electrode Properties of Ion-exchange Membranes. Z Physik Chem (Frankfurt) 1955 3 73-85. 

During the last two decades, tremendous work has been conducted on properties of ion exchange membranes, their behavior under various environmental conditions, and their interaction with electrodes as well as in determining the limiting factors influencing operation and cell life. 

There are three basic concepts that explain membrane phenomena the Nemst-Planck flux equation, the theory of absolute reaction rate processes, and the principle of irreversible thermodynamics. Explanations based on the theory of absolute reaction rate processes provide similar equations to those of the Nemst-Planck flux equation. The Nemst-Planck flux equation is based on the hypothesis that cations and anions independently migrate in the solution and membrane matrix. However, interaction among different ions and solvent is considered in irreversible thermodynamics. Consequently, an explanation of membrane phenomena based on irreversible thermodynamics is thought to be more reasonable. Nonequilibrium thermodynamics in membrane systems is covered in excellent books1 and reviews,2 to which the reader is referred. The present book aims to explain not theory but practical aspects, such as preparation, modification and application, of ion exchange membranes. In this chapter, a theoretical explanation of only the basic properties of ion exchange membranes is given.3,4... 

T Sata, Modification of properties of ion exchange membranes. III. Interaction between ion exchange membranes and surface active agents, Colloid Polym. Sci., 1978, 256, 52-67 YD. Grebenyuk, R.D. Chebotareva, S. Peters and V Linkov, Surface modification of anion exchange membranes to enhance anti-fouling characteristics, Desalination, 1998, 115, 313. 

T. Sata, Y. Kagiyama, F. Kurokawa and K. Takata, Jpn. Pat. JP 61-18930 (examined application) T. Sata and Y. Yamamoto, Modification of properties of ion exchange membranes. VIII. Change in properties of anion exchange membranes on introduction of hydrophobic groups, J. Polym. Sci., Polym. Phys. Ed., 1989, 27, 2229-2241. 

After preparing the ion exchange membranes, their properties and characteristics have to be evaluated according to the purpose of the experiment and their applications. When commercially available ion exchange membranes are industrially used, however, the basic properties of the membranes should be fully evaluated to derive excellent properties from the membranes. In this chapter, the basic properties of ion exchange membranes that need to be evaluated are explained and then the methods used to measure each property are explained. 

Primary Properties of Ion Exchange Membranes and their Evaluation (Characterization)... 

T. Sata, Modification of properties of ion-exchange membranes, Doctoral Thesis, 1975, p.10 V Svetlicic and Z. Ronrad, Study of the electrical resistance of alkaline earth ions in cation exchange membranes, J. Membr. Sci., 1979, 5, 129-134. 

R. Yamane, H. Motomura, T. Sata and Y. Mizutani, Characteristic properties of ion-exchange membranes prepared by Paste Method and analysis of the results of electrophoretic concentration of sea water, Nippon Kaisui Gakkaishi (Bull. Soc. Sea Water Sci. Jpn.), 1967, 20, 327-337. 

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