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Issue 45, 2018
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Comb-shaped sulfonated poly(ether ether ketone) as a cation exchange membrane for electrodialysis in acid recovery

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Abstract

To produce a cation exchange membrane (CEM) with high permselectivity and proton flux for electrodialysis (ED), a series of comb-shaped sulfonated poly(ether ether ketone) (SPEEK) membranes with long alkyl (butyl and octyl) side chains were synthesized using 1,1′-carbonyldiimidazole (CDI) as an activating reagent. The degree of substitution can be easily controlled by controlling the added amounts of CDI and reagents. The chemical structures were confirmed using a 1H NMR technique. Transparent and tough membranes were prepared by solution casting. A well-defined hydrophilic–hydrophobic separation was achieved, as confirmed by small-angle X-ray scattering (SAXS). The comb-shaped membranes with the well-defined hydrophilic–hydrophobic separation effectively allow the transport of H+, so higher H+ flux is achieved in the ED process with the comb-shaped SPEEK membranes than that obtained with the SPEEK membrane despite the higher membrane resistance resulting from the lower ion-exchange capacity and lower water uptake. Interestingly, the lower swelling ratio of the comb-shaped membranes can block Fe2+ transport through the membranes. Thus, the comb-shaped membranes show much higher H+/Fe2+ permselectivity than the pristine SPEEK membrane. The highest H+ flux of 2.41 × 10−7 mol cm−2 s−1 and H+/Fe2+ permselectivity of 32.13 are achieved for the SPEEK membrane with 30% substitution by octyl side chains. The performance is comparable with and even better than that of a commercial monovalent CEM from ASTOM. Considering the excellent thermal stability and mechanical properties, the comb-shaped SPEEK membranes are promising CEM materials for ED in acid recovery.

Graphical abstract: Comb-shaped sulfonated poly(ether ether ketone) as a cation exchange membrane for electrodialysis in acid recovery

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Publication details

The article was received on 08 Sep 2018, accepted on 15 Oct 2018 and first published on 16 Oct 2018


Article type: Paper
DOI: 10.1039/C8TA08718K
Citation: J. Mater. Chem. A, 2018,6, 22940-22950
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    Comb-shaped sulfonated poly(ether ether ketone) as a cation exchange membrane for electrodialysis in acid recovery

    L. Wang, M. Liu, J. Zhao, Y. Lei and N. Li, J. Mater. Chem. A, 2018, 6, 22940
    DOI: 10.1039/C8TA08718K

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