title: Local structures of ions at ion-exchange resin/solution interface.
abstract: The local structures of Cl- and Br- in anion-exchange resins have been studied by X-ray absorption fine structure (XAFS), and separation selectivity is discussed on the basis of results. When two different anion-exchange resins having trimethylammonium and dimethylammonium groups as anion-exchange groups are employed for ion-exchange experiments, slightly higher Br- selectivity has been obtained with the former. XAFS has indicated that the average hydration numbers for a given anion is not affected by the structure of the ion-exchange group, but that the extent of ion-association between the anion and the ion-exchange groups depends on the type of the ion-exchange group. Shorter interaction distance (and in turn stronger ion-association) has been confirmed for the dimethylammonium-type resin, and is consistent with lower Br- selectivity of this resin.
authors.affiliation: Department of Chemistry, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Harada
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Okada
mesh_terms: D000837:Anion Exchange Resins / Q000737:chemistry; D001965:Bromides / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D002852:Chromatography, Ion Exchange / Q000379:methods; D007474:Ion Exchange; D007475:Ion Exchange Resins / Q000737:chemistry*; D007477:Ions / Q000737:chemistry*; D008958:Models, Molecular; D012996:Solutions / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D014867:Water / Q000737:chemistry
chemical_list: D000837:Anion Exchange Resins; D001965:Bromides; D002712:Chlorides; D007475:Ion Exchange Resins; D007477:Ions; D012996:Solutions; D014867:Water