Enhanced selectivity and performance of heterogeneous cation exchange membranes through addition of sulfonated and protonated Montmorillonite

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:533

Article

Radmanesh, Farzaneh^1,2  Rijnaarts, Timon²  Moheb, Ahmad¹  Sadeghi, Morteza¹  de Vos, Wiebe M.² 

[1] Isfahan Univ Technol, Dept Chem Engn, Esfahan 8415683111, Iran

[2] Univ Twente, MESA Inst Nanotechnol, Membrane Sci & Technol, POB 217, NL-7500 AE Enschede, Netherlands

关键词: Electrodialysis;    Heterogeneous;    Cation exchange membrane;    Montmorillonite;    Ion selective;   

DOI  :  10.1016/j.jcis.2018.08.100

来源: Elsevier

【 摘 要 】

Novel heterogeneous cation exchange membranes, based on poly (ether sulfone) and cation exchange resin, were prepared with the addition of protonated and sulfonated Montmorillonite (MMT) nanopartides. Detailed investigations were then carried out studying the morphology, physical properties and the performance of membranes. It is observed that addition of MMT, leads to a substantially better distribution of ion exchange resin in the polymer matrix. This leads, at low loadings of MMT (0.5 wt.%), to membranes that are more hydrated, more hydrophilic and with higher ion exchange capacities. Especially at these low MMT loadings, substantially better membrane performance is observed, with higher permselectivities, lower areal resistances and increased ion transport during electrodialysis. A very surprising effect is that the addition of MMT has a strong effect on the selectivity of the membranes, especially towards Mg2+. A high affinity of the nanoclay towards Mg2+, selectively slows down Mg2+ transport through the nanoclay containing membrane. At low MMT loadings this leads to a much higher areal resistance for Mg2+, while for Na+ and Cat(2+) the areal resistance is decreased. This leads to resistance based selectivities of 5.5 for Na+/Mg2+ and 4.5 for Ca2+/Mg2+. Under more challenging electrodialysis operation selectivities become lower, but persist at 2.6 for Na+/Mg2+ and 2.04 for Ca2+/Mg2+, outperforming commercial Ralex membranes. Overall, the protonated clay leads to slightly better membrane performances and selectivities than the sulfonated clay, likely due to a better compatibility with PES. (C) 2018 Elsevier Inc. All rights reserved.

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