Constructing substrate of low structural parameter by salt induction for high-performance TFC-FO membranes
Constructing substrate of low structural parameter by salt induction for high-performance TFC-FO membranes
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盐诱导构建低结构参数基底的高性能TFC-FO膜
DOI：
10.1016/j.memsci.2020.117866
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发表时间：
2020-04-15
影响因子：
9.5
通讯作者：
Wang, Yan
中科院分区：
文献类型：
--
作者：
Shen, Liang;Zhang, Xuan;Wang, Yan
正向渗透(FO)是一种很有前途的膜技术，用于水处理和海水淡化。但是，内部浓差极化是FO中的一种独特现象，通常会导致性能急剧下降。本研究以氯化钠水溶液为凝固浴，研制了一种低聚合物浓度(4wt%)、低膜结构参数(S)的薄膜复合膜的聚丙烯腈(PAN)基板，该基板具有良好的FO性能。凝固浴中氯化钠的存在不仅显著影响相转化过程，形成具有微调形态结构的薄基片，而且有利于形成均匀、无缺陷的顶层聚酰胺(PA)层。系统地研究了凝固浴中氯化钠含量对PAN基片的形态和本征性质、所形成的PA层以及TFC膜的形态和FO性能的影响。此外，还在醋酸纤维素(CA)衬底上进行了扩展研究，以研究这种盐诱导方法制备高性能TFC膜的普适性。与对照TFC膜相比，改性TFC膜具有更低的S参数和更好的分离性能，具有更高的水通量(增加324%)和更低的反盐通量(减少58%)。
Forward osmosis (FO) is a promising membrane-based technology for water treatment and desalination. But, internal concentration polarization (ICP), a unique phenomenon in FO, generally leads to the sharp performance decline. In this study, a novel polyacrylonitrile (PAN) substrate with low polymer concentration (4 wt%) of the thin-film composite (TFC) membrane with a low membrane structural parameter (S) is developed with sodium chloride (NaCl) aqueous solution as the coagulation bath, and exhibits high performance for FO applications. The existence of NaCl in the coagulation bath not only affects the phase inversion process significantly, resulting in the formation of a thin substrate with finely tuned morphology structure, but also benefits the formation of a uniform and defect-free top polyamide (PA) layer. Effects of NaCl content in the coagulation bath on the morphology and intrinsic properties of resulting PAN substrates, the formed PA layer, as well as the morphology and FO performance of resulting TFC membranes, are investigated systematically. Moreover, an extended study on cellulose acetate (CA) substrate is also conducted to study the universality of this salt induction method to fabricate high-performance TFC membranes. Compared to the control TFC membrane, modified TFC membranes show much lower S parameters and superior separation performance with the higher water flux (324% increment) and lower reverse salt flux (58% reduction).