Synthesis of Ion Exchange Membranes and Their Application to MCDI
S. H. Kwon1, H. S. Shin2, C. S. Kim2, J. W. Rhim1*
1Department of Chemical Engineering, Hannam University, Daejeon, Korea
2Techwin Co. Ltd., Cheongju City, Choongcheongbuk-do, Korea
Capacitive deionization (CDI) which concept was first introduced by Caudle et. Al. is an electrochemically controlled method for removing salt from aqueous solutions by utilizing the principle of electrosorption consisting of adsorption and desorption of ions at the electric double layer of an electrode’s surface. CDI uses carbon electrodes that have large surface areas to increase the adsorption capacity of the electrodes. However, because carbon electrodes have a porous structure, there can be a problematic decline in efficiency during operation of the process. To address this problem, membrane capacitive deionization (MCDI) has been recently introduced, which combines ion exchange membranes with the carbon electrodes.
In this presentation, the followings will be introduced. For ion exchange membranes, the aminated polysulfone membranes as the anion exchange membrane and the sulfonated polyphenylene oxide as the cation exchange membrane were synthesized, respectively, and their membrane characterization were carried out by using FT-IR, swelling degree, contact angles, ion exchange capacity, and ion conductivity. The coated carbon electrodes with the synthesized polymers were applied to MCDI experiments. The influent salt concentration of NaCl was varied from 100 ppm to 500 ppm, and the applied cell voltages was from 0.8 to 1.2, and the adsorption time/desorption time of 2/1, 3/1, 5/1 was used and also the feed flow rate was 10, 25 and 30 ml/min. From this parameters, the salt removal efficiency, conductivity of the treated water as a function of cell potential, changes in current at different cell potentials, and the relative concentration of the effluent, etc., will be discussed in more detail.
1. D.D. Caudle, J.H. Tucker, J.L. Cooper, B.B. Arnold and A. Papastamataki, Electrochemical demineralization of water with carbon electrodes, Research Report, Oklahoma University Research Institute, 1966.