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Yamaki, Tetsuya*; Goto, Mitsuaki*; Sawada, Shinichi*; Koshikawa, Hiroshi*; Kitamura, Akane; Higa, Mitsuru*
QST-M-8; QST Takasaki Annual Report 2016, P. 35, 2018/03
We prepared ion exchange membranes by a heavy-ion-track grafting method, and then used them for seawater concentration process. Both the water uptake and resistance were lower for our ion-track grafted membranes than for the conventional 
-ray-grafted membranes. The results would be because local and high-density energy deposition due to the ion beam enabled us to control the membrane structure in a nanometer scale. We demonstrate our membranes are suitable for this application.
-ray irradiation graft polymerization methodGoto, Mitsuaki*; Omori, Masayuki*; Yamaki, Tetsuya; Sawada, Shinichi; Koshikawa, Hiroshi; Kitamura, Akane; Higa, Mitsuru*
no journal, ,
We have prepared cation exchange membranes for applications to electrochemical energy-conversion devices by swift-heavy-ion irradiation, and then investigated their charge density, 
, a concentration of fixed charge groups, in comparison with that of the conventional -ray-grafted membranes. Poly(ethylene-
-tetrafluoroethylene) films with a 25 
m thickness were irradiated in a vacuum chamber with 560 MeV 
Xe and subsequently immersed in a grafting solution containing sodium 
-styrenesulfonate at 60
C. The charge density was estimated through the measurement of the membrane potential in an aqueous solution of potassium chloride. Our membranes exhibited higher charge density (reaching 2.40 mol/dm
at maximum) than the -ray-grafted samples probably due to track structures characteristic of the bombarding heavy ions.
Goto, Mitsuaki*; Yamaki, Tetsuya; Koshikawa, Hiroshi; Sawada, Shinichi; Kitamura, Akane; Higa, Mitsuru*
no journal, ,
We have exploited a grafting technique with heavy-ion beams to create ion exchange membranes for various practical applications such as fuel cells and water desalination systems. In this study, instead of styrene that is a common monomer, sodium styrene sulfonate (SSS) was for the first time employed for this so-called ion-track grafting. A 25 m-thick poly(vinylidene fluoride) film was bombarded with 560 MeV Xe at a fluence of 3.0
10
or 1.010
ions/cm
, and subsequently immersed in a SSS grafting solution at 60C. The charge density was estimated through the measurement of the membrane potential in an aqueous solution of potassium chloride. Our membranes exhibited higher charge density than the conventional or commercially-available samples probably due to track structures characteristic of the bombarding heavy ions.
Sawada, Shinichi*; Goto, Mitsuaki*; Koshikawa, Hiroshi*; Kitamura, Akane; Higa, Mitsuru*; Yamaki, Tetsuya*
no journal, ,
We prepared cation exchange membranes (CEMs) and anion exchange membranes (AEMs) by a heavy-ion-track grafting method, and then used them for seawater electrodialysis process. The concentration of the obtained seawater was higher than that in the case of the commercial CEM/AEM. This result demonstrates our CEMs and AEMs are suitable for this application.
Sawada, Shinichi*; Goto, Mitsuaki*; Koshikawa, Hiroshi*; Kitamura, Akane; Higa, Mitsuru*; Yamaki, Tetsuya*
no journal, ,
In this study, we prepared ion exchange membranes (CEMs) by our ion-track-grafting technique and investigated their ion and water transport properties. The CEM preparation involved irradiation of ethylene-co-tetrafluoroethylene films with 310 MeV Kr beam, grafting of styrene into the resulting latent tracks, and sulfonation of styrene units. Membrane resistance was measured by an AC impedance method. Osmotic-pressure-driven water flux was measured by using a permeation cell containing two compartments filled with pure water and an aqueous 3 mol/L NaCl solution. At higher IEC, the membrane resistance decreased, while the water flux increased. Interestingly, the water flux of the ion-track-grafted CEMs is significantly lower than that of commercially products and a conventional -ray-grafted CEM. This result demonstrates a great potential for industrial electrodialysis. In conclusion, unique one dimensional ionic channels achieved by the ion-track-grafting can facilitate Na+ transport and hinder water permeation.
