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Separations of cations using methacrylate-based low-capacity cation-exchangers
React. Polym. 17 (1992) 115-139
122
electron diffraction, scanning electron microscopy and energy dispersive spectrometry in order to image directly and characterize these particles. The elemental composition, structure, size, and dispersion within the Nation membrane were also investigated. By means of electron diffraction, the structure of the particles was identified as mainly very fine grained polycrystalline tetragonal TiO2 of the rutile type. The technique described for the in situ synthesis shows a number of advantages over the more conventional procedures, including simplicity as well as retention of very small particles. A mechanism for this precipitation is proposed. The sorption of other semiconductors, inorganic and organic, is actually being investigated. Reference:
Thin Solid Films, 185 (1990)
181-188.
Wofatit anion-exchangers for removing nitrates from potable water R. H e l l m i g
Department of Ion Exchangers and Molecular Sieves, VEB Chemikombinat Bitterfeld, WilhelmHeck-strasse 54, 4500 Dessau, Germany There are two principal methods for the elimination of nitrate ions from drinking water by means of Wofatit anion-exchangers: (1) Complete deionisation of the water by combination of cation and anion exchange. All salts are completely eliminated in this process. (2) Neutral exchange process - the nitrate ions which might be harmful are exchanged in the course of this process by harmless chloride, hydrogen carbonate or possibly sulphate ions. The lecture deals particular with the nitrate-selective Wofatit SN 36 L, its advantages, in comparison with other anion-exchangers, its limits of application as well as with regeneration processes which are environmentally friendly.
Detection and determination of fluoride and chloride with non-suppressed ion chromatography using acetylacetonate eluent Naoki Hirayama and Tooru Kuwamoto
Department of Chemistry, Faculty of Science, Kyoto University, Kitasirakawa, Sakyo-ku, Kyoto 606, Japan /3-Diketonates in aqueous solution exist in different chemical states due to keto-enol tautomerism and the dissociation equilibria. The use of acac- as the element has been shown to be useful for the separation and determination of fluoride and chloride, which are retained very weakly on anion exchange resins. This ehent has a relatively low driving strength and was very effective for separating the fluoride peak from the first (or second) system peak. Fluoride and chloride were measured with relatively high sensitivity and the metal cations in the sample solution, which have influence on the base line of the chromatogram, were successfully eliminated, because acac- is a very effective chelating reagent. Reference: Z
Chromatogr.,523 (1990)
257-264.
Separations of cations using methacrylate-based low-capacity cation-exchangers J. H r a d i l a, F. Svec 1, A . A . A r a t s k o v a
2,
L . D . B e l j a k o v a 2 a n d V.I. O r l o v 2
1 Institute of Macromolecular Chemistry, Czechoslovak Academy of Sciences, 162 06 Prague 6, Czechoslovakia z Institute of Physical Chemistry, Academy of Sciences of USSR, 117071 Moscow, USSR The possibility of using macroporous methacrylate-based low-capacity ion-exchangers in the separation of cations of alkali metals, alkaline earth metals, transition and heavy metals was tested. The separation conditions were optimized with respect to the composition of the eluent (content of ethylenediamine, tartaric acid, organic solvent,
React. Polym. 17 (1992)115-139
123
and pH). The retention of cations on methacrylate ion-exchangers were compared with those on derivatives of styrene-divinylbenzene and silica gel. The detection limits obtained using the usual apparatus and method were 2.5 x 10 -s g. References: J.
Chromatogr.,509 (1990) 369-367;
J.
Chromatogr.,475 (1989) 209-217.
Adsorption-elution properties of newly synthesized adsorbents T. Itagaki, T. M o r i t a , J. W a t a n a b e a n d H. T e s h i m a
Research Center Mitsubishi Kasei Corporation, 1000, Kamoshida-cho, Midori-ku, Yokohama 227, Japan Synthetic adsorbents with large surface areas were developed. The adsorbents were made of styrene and divinylbenzene monomers. They were synthesized by a two-step reaction, polymerization and alkylation reaction. Adsorption capacities of several substances were examined and were characterized for groups of adsorbents: (1) adsorbents as having almost the same surface area with different peak pore radius; (2) adsorbents having different surface areas with almost the same peak pore radius. The substances were chosen from an antibiotic intermediate and proteins with various molecular weights (those molecular weights were in the range from several hundreds to tens of thousands). According to the adsorption capacity measurements, there exists a good correlation between adsorption capacities for cephalosporin-C and the surface areas of adsorbents. However, in the case of large molecules like proteins, adsorbed amounts are affected by the pore sizes of the adsorbents. Molecular sieve effects due to pore size distribution of adsorbents are effective for the separation of small from large molecules like proteins. Reference: M. Streat, Ion Exchange for Industry, Ellis-Horwood, 1988, p. 232.
Thermodynamic study of ion exchange of alkaline earth metal ions on a weak cation-exchanger, Bio-Rex 70 B.L. J a n g i d a 1, P.V. A c h u t h a n 2 a n d M. S u n d a r e s a n 1
1Analytical Chemistry Division, Bhabha Atomic Research Centre, Bombay 400085, India 2 Fuel Reprocessing Division, BARC, Bombay 400085, India Standard free energy, enthalpy and entropy changes for the cation exchange of magnesium, calcium, strontium and barium with sodium ions on a carboxylic type weak cation-exchanger, Bio-Rex 70 resin, has been estimated in dilute 0.1 N aqueous chloride solutions from ionic distribution and calorimetric measurements at 298 K. The strong binding for the alkaline earth metal ions by the resin was reflected by the large negative values of the standard free energy changes. The exchange reactions were endothermic and the endothermicity was maximum for calcium-sodium exchange due to the stronger complex formation between the calcium and carboxylate ionogenic group. The reactions were thus entropy driven. The magnitude of the selectivities of the alkaline earth metal ions were significantly higher than those on polystyrene sulfonate type of exchangers. The order of selectivity was calcium > barium = magnesium > strontium. The higher selectivity and the random order of the selectivity have been attributed to the greater dehydration and complexing of the cations by the RCOO- group.
Investigation on kinetics of polyvalent ions in selective ion-exchangers A.I. Kalinitchev, T . D . S e m e n o v s k a y a , V.Ja. F i l i m o n o v a n d T . D . S h e p e t y u k
Institute of Physical Chemistry, USSR Academy of Science, Lenin Avenue 31, Moscow 117915, USSR Our previous theoretical model of ion-exchange kinetics in selected systems is extended for polyvalent ion-exchangers. Kinetic investigations were carried out on the selective ion-exchangers ANKB-35 and AN-18-10P for H-RNi, Ni-RH, O-RAg, C1-RCu and Ni-RNa exchangers using a home-made flow cell filled with a thin layer of
122
electron diffraction, scanning electron microscopy and energy dispersive spectrometry in order to image directly and characterize these particles. The elemental composition, structure, size, and dispersion within the Nation membrane were also investigated. By means of electron diffraction, the structure of the particles was identified as mainly very fine grained polycrystalline tetragonal TiO2 of the rutile type. The technique described for the in situ synthesis shows a number of advantages over the more conventional procedures, including simplicity as well as retention of very small particles. A mechanism for this precipitation is proposed. The sorption of other semiconductors, inorganic and organic, is actually being investigated. Reference:
Thin Solid Films, 185 (1990)
181-188.
Wofatit anion-exchangers for removing nitrates from potable water R. H e l l m i g
Department of Ion Exchangers and Molecular Sieves, VEB Chemikombinat Bitterfeld, WilhelmHeck-strasse 54, 4500 Dessau, Germany There are two principal methods for the elimination of nitrate ions from drinking water by means of Wofatit anion-exchangers: (1) Complete deionisation of the water by combination of cation and anion exchange. All salts are completely eliminated in this process. (2) Neutral exchange process - the nitrate ions which might be harmful are exchanged in the course of this process by harmless chloride, hydrogen carbonate or possibly sulphate ions. The lecture deals particular with the nitrate-selective Wofatit SN 36 L, its advantages, in comparison with other anion-exchangers, its limits of application as well as with regeneration processes which are environmentally friendly.
Detection and determination of fluoride and chloride with non-suppressed ion chromatography using acetylacetonate eluent Naoki Hirayama and Tooru Kuwamoto
Department of Chemistry, Faculty of Science, Kyoto University, Kitasirakawa, Sakyo-ku, Kyoto 606, Japan /3-Diketonates in aqueous solution exist in different chemical states due to keto-enol tautomerism and the dissociation equilibria. The use of acac- as the element has been shown to be useful for the separation and determination of fluoride and chloride, which are retained very weakly on anion exchange resins. This ehent has a relatively low driving strength and was very effective for separating the fluoride peak from the first (or second) system peak. Fluoride and chloride were measured with relatively high sensitivity and the metal cations in the sample solution, which have influence on the base line of the chromatogram, were successfully eliminated, because acac- is a very effective chelating reagent. Reference: Z
Chromatogr.,523 (1990)
257-264.
Separations of cations using methacrylate-based low-capacity cation-exchangers J. H r a d i l a, F. Svec 1, A . A . A r a t s k o v a
2,
L . D . B e l j a k o v a 2 a n d V.I. O r l o v 2
1 Institute of Macromolecular Chemistry, Czechoslovak Academy of Sciences, 162 06 Prague 6, Czechoslovakia z Institute of Physical Chemistry, Academy of Sciences of USSR, 117071 Moscow, USSR The possibility of using macroporous methacrylate-based low-capacity ion-exchangers in the separation of cations of alkali metals, alkaline earth metals, transition and heavy metals was tested. The separation conditions were optimized with respect to the composition of the eluent (content of ethylenediamine, tartaric acid, organic solvent,
React. Polym. 17 (1992)115-139
123
and pH). The retention of cations on methacrylate ion-exchangers were compared with those on derivatives of styrene-divinylbenzene and silica gel. The detection limits obtained using the usual apparatus and method were 2.5 x 10 -s g. References: J.
Chromatogr.,509 (1990) 369-367;
J.
Chromatogr.,475 (1989) 209-217.
Adsorption-elution properties of newly synthesized adsorbents T. Itagaki, T. M o r i t a , J. W a t a n a b e a n d H. T e s h i m a
Research Center Mitsubishi Kasei Corporation, 1000, Kamoshida-cho, Midori-ku, Yokohama 227, Japan Synthetic adsorbents with large surface areas were developed. The adsorbents were made of styrene and divinylbenzene monomers. They were synthesized by a two-step reaction, polymerization and alkylation reaction. Adsorption capacities of several substances were examined and were characterized for groups of adsorbents: (1) adsorbents as having almost the same surface area with different peak pore radius; (2) adsorbents having different surface areas with almost the same peak pore radius. The substances were chosen from an antibiotic intermediate and proteins with various molecular weights (those molecular weights were in the range from several hundreds to tens of thousands). According to the adsorption capacity measurements, there exists a good correlation between adsorption capacities for cephalosporin-C and the surface areas of adsorbents. However, in the case of large molecules like proteins, adsorbed amounts are affected by the pore sizes of the adsorbents. Molecular sieve effects due to pore size distribution of adsorbents are effective for the separation of small from large molecules like proteins. Reference: M. Streat, Ion Exchange for Industry, Ellis-Horwood, 1988, p. 232.
Thermodynamic study of ion exchange of alkaline earth metal ions on a weak cation-exchanger, Bio-Rex 70 B.L. J a n g i d a 1, P.V. A c h u t h a n 2 a n d M. S u n d a r e s a n 1
1Analytical Chemistry Division, Bhabha Atomic Research Centre, Bombay 400085, India 2 Fuel Reprocessing Division, BARC, Bombay 400085, India Standard free energy, enthalpy and entropy changes for the cation exchange of magnesium, calcium, strontium and barium with sodium ions on a carboxylic type weak cation-exchanger, Bio-Rex 70 resin, has been estimated in dilute 0.1 N aqueous chloride solutions from ionic distribution and calorimetric measurements at 298 K. The strong binding for the alkaline earth metal ions by the resin was reflected by the large negative values of the standard free energy changes. The exchange reactions were endothermic and the endothermicity was maximum for calcium-sodium exchange due to the stronger complex formation between the calcium and carboxylate ionogenic group. The reactions were thus entropy driven. The magnitude of the selectivities of the alkaline earth metal ions were significantly higher than those on polystyrene sulfonate type of exchangers. The order of selectivity was calcium > barium = magnesium > strontium. The higher selectivity and the random order of the selectivity have been attributed to the greater dehydration and complexing of the cations by the RCOO- group.
Investigation on kinetics of polyvalent ions in selective ion-exchangers A.I. Kalinitchev, T . D . S e m e n o v s k a y a , V.Ja. F i l i m o n o v a n d T . D . S h e p e t y u k
Institute of Physical Chemistry, USSR Academy of Science, Lenin Avenue 31, Moscow 117915, USSR Our previous theoretical model of ion-exchange kinetics in selected systems is extended for polyvalent ion-exchangers. Kinetic investigations were carried out on the selective ion-exchangers ANKB-35 and AN-18-10P for H-RNi, Ni-RH, O-RAg, C1-RCu and Ni-RNa exchangers using a home-made flow cell filled with a thin layer of