Separation of small organic ions from salts by ion-exchange membrane in electrodialysis

Authors

  • Yang Zhang,

    Corresponding author
    1. Dept. of Chemical Engineering, Laboratory for Applied Physical Chemistry and Environmental Technology, K.U.Leuven, B-3001 Leuven, Belgium
    • Dept. of Chemical Engineering, Laboratory for Applied Physical Chemistry and Environmental Technology, K.U.Leuven, B-3001 Leuven, Belgium
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  • Luc Pinoy,

    1. Dept. of Industrial Engineering, Laboratory for Chemical Process Technology, KaHo St.-Lieven, Associated to K.U.Leuven, as Faculty of Industrial Sciences, B-9000 Gent, Belgium
    2. Dept. of Molecular and Microbial Sciences, K.U.Leuven, B-3001 Leuven, Belgium
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  • Boudewijn Meesschaert,

    1. Dept. of Molecular and Microbial Sciences, K.U.Leuven, B-3001 Leuven, Belgium
    2. Dept. of Industrial Sciences and Technology, Katholieke Hogeschool Brugge-Oostende, Associated to K.U.Leuven, as Faculty of Industrial Sciences, B-8400 Oostende, Belgium
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  • Bart Van der Bruggen

    1. Dept. of Chemical Engineering, Laboratory for Applied Physical Chemistry and Environmental Technology, K.U.Leuven, B-3001 Leuven, Belgium
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Abstract

Electrodialysis (ED) can be applied in the food and fermentation industry for separating inorganic salts and organic ions from other fractions. However, the separation efficiency for small organic ions should be understood in detail. In this article, the membrane selectivity and transport mechanism of small organic ions from mixed salts by ion-exchange membranes are theoretically and experimentally investigated. First of all, the influence of current density on the solute flux (organic ions and inorganic ions) and on membrane selectivity (between organic ions and inorganic ions and between different organic ions) in ED has been studied. The selectivity was shown to be influenced by changing the applied current density. It was observed that separation of inorganic ions from organic solutes was feasible, but the selectivity was dependent on the size, charge, and functional groups of the organic ions. Furthermore, results imply that binary organic anions with larger molar mass (>130, i.e., aspartate and tartrate) can be adsorbed onto the membrane free volume and hence form a charged double layer, which affects membrane selectivity. Finally, competition between small organic and inorganic ions is discussed by comparison of the concentration profiles and current efficiencies of the different anions. © 2010 American Institute of Chemical Engineers AIChE J, 2011

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