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Anion exchange membranes with excellent monovalent anion perm-selectivity for electrodialysis applications
Chemical Engineering Research and Design ( IF 3.9 ) Pub Date : 2020-04-01 , DOI: 10.1016/j.cherd.2020.03.021
Xiaoyao Wang , Xu Zhang , Cuiming Wu , Xiaozhao Han , Chao Xu

In recent years, ion exchange membranes with monovalent ion perm-selectivity are highly desirable. Here, two strategies were adopted simultaneously to prepare anion exchange membranes with excellent monovalent anion perm-selectivity. One is to adjust membranes’ hydrophobicity by grafting single long chain tertiary amines of different alkyl chain lengths (N,N-dimethylhexadecylamine (DMA16), N,N-Dimethylhexylamine (DMHA), and trimethylamine (TMA)) onto bromomethylated poly (phenylene oxide) (BPPO) backbones and regulating the molar ratio of the tertiary amine and the bromobenzyl in BPPO. Results show that the obtained membrane C16-0.5, which was grafted with the longest tertiary amine (DMA16) and has the lowest molar ratio of DMA16 and the bromobenzyl in BPPO, exhibits the lowest water uptake (WU) and highest monovalent anion perm-selectivity (PSO4Cl) between Cl and SO42− (12.84). The other is to regulate membranes’ compactness through post-treatments, including heat treatment and surface modification by forming a polypyrrole layer on the membrane surface. Results show that membrane C16-0.75-H120, which was under the heat treatment of 120 °C, shows a higher PSO4Cl (7.58) than membrane C16-0.75 (5.02) without any heat treatment; moreover, membrane C16-0.75-pr, which was coated with a polypyrrole layer on the surface, has a higher PSO4Cl (9.0) than membrane C16-0.75 (5.02) without any surface modification. In addition, membranes C16-0.5, C16-0.75-H120 and C16-0.75-pr have more excellent PSO4Cl than the commercial membrane ASV (6.52). To sum up, results in this study suggest that both of the two strategies are highly effective to improve membranes’ perm-selectivity.



中文翻译:

具有出色的单价阴离子渗透选择性的阴离子交换膜,适用于电渗析应用

近年来,非常需要具有单价离子渗透选择性的离子交换膜。在这里,同时采用两种策略来制备具有优异的单价阴离子渗透选择性的阴离子交换膜。一种是通过接枝具有不同烷基链长度的单个长链叔胺(N,N-二甲基十六烷基胺(DMA16),N,N-将二甲基己基胺(DMHA)和三甲基胺(TMA)置于溴甲基化的聚苯醚(BPPO)骨架上,并调节BPPO中叔胺和溴苄基的摩尔比。结果表明,所获得的膜C16-0.5接枝了最长的叔胺(DMA16),并且在BPPO中具有最低的DMA16和溴苄基摩尔比,具有最低的吸水率(WU)和最高的单价阴离子渗透选择性。 (P小号Ø4C)氯间-和SO 4 2-(12.84)。另一种是通过后处理来调节膜的致密性,这些后处理包括通过在膜表面上形成聚吡咯层来进行热处理和表面改性。结果表明,经120°C热处理的C16-0.75-H120膜显示出更高的P小号Ø4C(7.58)比膜C16-0.75(5.02)无需任何热处理;而且,在表面覆盖有聚吡咯层的膜C16-0.75-pr具有更高的P小号Ø4C(9.0)比膜C16-0.75(5.02)进行了任何表面修饰。此外,膜C16-0.5,C16-0.75-H120和C16-0.75-pr具有更优异的性能P小号Ø4C比市售的ASV膜(6.52)。综上所述,本研究结果表明,两种策略均能有效提高膜的渗透选择性。

更新日期:2020-04-01
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