Journal of Ion Exchange
Online ISSN : 1884-3360
Print ISSN : 0915-860X
ISSN-L : 0915-860X
Volume 17, Issue 2
Displaying 1-6 of 6 articles from this issue
  • Akihiko TANIOKA
    2006 Volume 17 Issue 2 Pages 32-40
    Published: May 20, 2006
    Released on J-STAGE: March 18, 2010
    JOURNAL FREE ACCESS
    The transport phenomena across the ion-exchange membrane in organic solvent and in low water content were analyzed on the basis of the Donnan equilibrium and the Nernst-Planck equation of ion flux considering the Fuoss ion-pair formalism, and the theoretical predictions agreed well with the experimental data. The theoretical prediction clarifies the charge effectiveness parameter (Q-value) and the ionic mobility are the function of dielectric constant. This theoretical treatment can be applied to “Fuel cell system using methanol (DMFC) ”, “Fuel cell system in low water content”, “Metal recovery from waste water with organic solvent”, “Highly salt condensation”, and “Ionic transport across ionic channel”.
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  • Hitoshi MIMURA
    2006 Volume 17 Issue 2 Pages 41-50
    Published: May 20, 2006
    Released on J-STAGE: March 18, 2010
    JOURNAL FREE ACCESS
    The advancement of nuclide separation in the processing of high level liquid wastes (HLLWs) was reviewed. Selective separation and recovery of useful radioactive nuclides (Cs, Pd and Am) containing in HLLWs are of importance in relation to the partitioning and their effective utilization. The granular composites of AMP (ammonium molybdophosphate) immobilized with porous alumina or calcium alginate exhibited a high selectivity towards Cs, and the mutual separation of Cs/Rb was performed through the packed column. The fine crystals of insoluble ferrocyanides (KNiFC and KCuFC) were granulated by microencapsulation with polymer gels of alginates and had a high selectivity towards Pd. The extractants (Cyanex 301, Cyanex 302) were also encapsulated in the matrices of alginates and alginic acid. The microcapsule of Cyanex 302-CaALG had a relatively large separation factor of Pd/Ru and Pd/Rh, and Pd ions were effectively separated from Ru and Rh. The Cyanex 301-HALG microcapsule with a high affinity for Am was effective for the chromatographic separation of Am/Eu. The microencapsulation methods for the granulation of fine inorganic ion-exchanges and extractants are thus expected for the advanced nuclide separation in the nuclear fuel cycle and environmental remediation.
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  • Keisuke OHTO
    2006 Volume 17 Issue 2 Pages 51-58
    Published: May 20, 2006
    Released on J-STAGE: March 18, 2010
    JOURNAL FREE ACCESS
    Three novel types of ion exchange regins containing calixarene tetraacetic acid have been prepared to investigate metal adsorption behavior by batch-wise and column chromatographical methods. Metal selectivity of the resins for divalent metals is as follows: Pb (II) >>Cu (II) >Zn (II) ≥Ni (II) ≥Co (II) . Since the adsorption property as the selectivity and so on is similar to the extraction one of calixarene derivatives as solvent extraction reagents, the derivatives were found to be resinificated with keeping the extraction property. Maximum loading capacity of lead on the resin is deeply related not only to flexibility of calixarene moiety in the resin as the adsorption stoichiometry of calixarene and lead is same to be 1: 2 as the extraction one, but also to content of calixarene moiety per resin weight. The lead loading capacity of the crosslinked resin is higher than those of the supported and the impregnated resins. Column chromatographical separation of divalent lead and zinc by the resins has been effectively achieved. The prepared resins show sodium effect for enhanced metal adsorption similar to the enhanced metal extraction with calix [4] arene tetraacetic acid.
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  • Yoshinobu MIYAZAKI
    2006 Volume 17 Issue 2 Pages 59-66
    Published: May 20, 2006
    Released on J-STAGE: March 18, 2010
    JOURNAL FREE ACCESS
    In order to understand adsorption mechanisms of ion-exchangers and selective adsorbents, properties of the gel internal solution, and the structure and the reactivity of adsorbed species should be clarified. This review article describes author's studies using multinuclear NMR method on the hydrolysis reactions, acid dissociation and complexation of oxoanions adsorbed onto ion-exchangers and selective adsorbents. The hydrolysis of cyclo-triphosphate in anion-exchange resins was significantly retarded compared to that in a basic solution. This retardation was shown to be entirely due to a much more unfavorable ΔH for the reaction in the resin phase. Boron and vanadium (V) species adsorbed onto polysaccharide gels were characterized: 1: 1 (α, β) and/or (α, γ), and 1: 2 (α, β) (α, β), (α, γ) (α, γ) and/ or (α, β) (α, γ) complexes for boron in sephadex and cellulose, and a 1: 1 (N, O, O) complex for vanadium (V) in ECTEOLA-cellulose. The adsorption behavior of boron onto N-methylglucamine resin was well interpreted in terms of pH in the resin phase (not in the external solution) estimated by NMR measurements of a probe species. The maximum adsorption around pH 9 of the equilibrated solution is due to the fact that the pH in the resin phase remains higher than that in the external solution.
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  • Mohammad OUTOKESH, Hitoshi MIMURA, Yuichi NIIBORI, Kouichi TANAKA
    2006 Volume 17 Issue 2 Pages 67-74
    Published: May 20, 2006
    Released on J-STAGE: March 18, 2010
    JOURNAL FREE ACCESS
    An organic extractant, Cyanex 302, having a relatively high selectivity toward the soft metal ions, was microencapsulated in the alginate biopolymer matrices. Various shapes of microcapsules such as granule, fiber and film were prepared by contacting a kneaded sol of HA and sodium alginate with a gelling solution. The uptake of Cd2+ for microcapsules attained equilibrium within 20 h, and Cd2+ ions were selectively adsorbed on microcapsules even in the presence of 0.1 M HNO3 or 1 M NaNO3. The uptake (%) of other heavy metal ions, Ag, Pb, Cu and Zn on microcapsules was above 96%, suggesting a possibility of simultaneous removal of soft metal ions. The uptake ability of Cd2+ for microcapsules was superior to that for conventional adsorbents in the presence of 0.1M HNO3. The column packed with granular microcapsules was effective for the successive removal of Cd2+ ions.
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  • Kazuya UEZU, Kentaro MIYOSHI
    2006 Volume 17 Issue 2 Pages 75-82
    Published: May 20, 2006
    Released on J-STAGE: March 18, 2010
    JOURNAL FREE ACCESS
    We carried out molecular dynamics simulations of two types of macromolecules, i.e. reverse micelles and, β-1, 3-Dglucans to gain an atomic-level picture of the structure and dynamics.
    For reverse micelle simulations, we employed sodium bis (2-ethylhexyl) sulfosuccinate, known as AOT and a new synthesized surfactant, dioleyl phosphoric acid (abbreviated as DOLPA) . After substantial conformational rearrange-ment during the simulations, the final configurations appear to have roughly spherical shapes in the aggregate. Surfactant molecules almost cover the whole core waters. The core of the DOLPA micelle changed from a spherical to an oval shape, while the core remained spherical in an AOT reverse micelle. From the coordination number among micelle components, the difference comes from the interaction between potassium ions and the hydrophilic groups of surfactant, i.e. the phosphoric acid groups of DOLPA and the sulfuric acid groups of AOT.
    The β-1, 3-D-glucan forms a right-handed triple helix, and it has been believed that the intermolecular hydrogen bond is present at the center of the helix to maintain the structure. In this hydrogen bond model, three 2nd hydroxyl groups form an inequilateral hexagonal shape perpendicular to the helix axis. We carried out semi-empirical quantum mechanis and ab initio calculations for β-1, 3-D-glucan models, and proposed a new intermolecular hydrogen bond. In our model, the hydrogen bond forms between the O2 atoms on different x-y planes along the helix, hence the hydrogen bond is not perpendicular to the helix axis. The new hydrogen bonds are connected along the helix, traversing three glucan chains to make a left-handed helix. Furthermore, by molecular dynamics simulations for β-1, 3-D-glucan in aqueous solution, the new hydrogen bond we proposed is found to be a major type for most cases.
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