A demand of diversification and upgrading of the material is intensified by the advance of technology. The preparation of composite materials is one influential technique to attempt upgrading and individualization of the material. Authors have studied on the functional enhancement of several inorganic ion exchangers through composite materials formation. In this paper, the outline and the respective functions of four composite materials prepared by us: silicate crystallite mesoporous material; bactericidal allophanic material; granular inorganic ion exchanger; environmentally harmonious ion exchanger, is described.

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X-ray absorption fine structure (XAFS) has proved very efficient for studying the local structure of counterions in ion-exchange resins. The principle of XAFS is briefly outlined, and its applications to ion-exchange systems are discussed in this review. When Br^- and Cl^--form anion-exchange resins are soaked in water, two different structures are detected; one comes from hydrated counterions, while the other is attributed to those bound by ion-exchange groups. A simple mathematical procedure has allowed us to separate the contributions from these two different origins, and finally indicates that ca 40% of counterions are dissociated from the ion-exchange sites when sufficient amount of water available for hydration. This structure is found for the anions attracted by the surface monolayers. Ion-exchange selectivity is also discussed based on these results.

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The Polymer Electrolyte Fuel Cell co-generation system can genetrate electricity and hot water with high efficiency, so this system is expected to prevent global warming. The fluorinated cation exchange membranes are used in the fuel cell stack, and ion exchange resins are used for the purification of water necessary to produce hydrogen from natural gas or LPG. We are developing Continuous Electric DeIonization (CEDI) system for the water purification of fuel cell system. Compaired with ion exchange resin cartridge, this system do not need frequent exchange. So this system will satisfy the request of user to reduce the maintenance frequency.

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