Printing zwitterionic self-assembled thin film composite membranes: Tuning thickness leads to remarkable permeability for nanofiltration
Printing zwitterionic self-assembled thin film composite membranes: Tuning thickness leads to remarkable permeability for nanofiltration
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DOI：
10.1016/j.memsci.2021.119428
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发表时间：
2021-05
影响因子：
9.5
通讯作者：
Xin Qian;T R Ravindran;Samuel J. Lounder;A. Asatekin;J. McCutcheon
中科院分区：
文献类型：
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作者：
Xin Qian;T R Ravindran;Samuel J. Lounder;A. Asatekin;J. McCutcheon
两性离子共聚物自组装膜已被证明对纳滤应用具有令人印象深刻的选择性。用于制造这些不对称膜的常规方法，例如浇铸后相转化，通常导致形成厚的选择性层，这会限制渗透性。在这项工作中，我们评估使用电喷雾印刷到UF膜基板上的两亲性两性离子选择性层的薄层。染料用于探测这些膜的排斥，而它们的厚度相比于浇铸方法减少了几个数量级。随着厚度减小，发现水渗透性成比例地增加，而对于某些染料保持染料截留率。有人发现，一个阈值的最小厚度是必需的，以保持对一些染料分子的排斥，而聚合物膜的固有渗透性作为厚度的函数而变化。退火的膜被发现增加渗透性，以及没有显着损失的排斥。值得注意的是，发现我们的退火超薄TFC膜之一表现出180 LMH/巴的水渗透值和99.67%的叶绿酸截留率。有趣的是，这种渗透率是无法区分的支持UF膜渗透，这表明，甚至更高的渗透率没有排斥损失是可能的与更多的渗透性支持层。
Zwitterionic copolymer self-assembled membranes have been shown to have impressive selectivity for nanofiltration applications. Conventional approaches used to fabricate these asymmetric membranes, such as casting followed by phase inversion, typically result in thick selective layers being formed that can limit permeance. In this work, we evaluate the use of electrospray to print thin layers of amphiphilic zwitterionic selective layers onto UF membrane substrates. Dyes are used to probe the rejection of these membranes while their thickness is reduced by orders of magnitude compared to casting methods. As thickness is decreased, water permeance was found to proportionally increase while dye rejection was maintained for some dyes. It was found that a threshold minimum thickness was required to maintain rejection for some dye molecules while the intrinsic permeability of the polymer films changed as a function of thickness. Annealing the membranes was found to increase permeance as well without a significant loss of rejection. Notably, one of our annealed ultra-thin TFC membranes was found to exhibit a water permeance value of 180 LMH/bar and a chlorophyllin rejection at 99.67%. Interestingly, this permeance is indistinguishable from the supporting UF membrane permeance, suggesting that even higher permeance without rejection loss is possible with more permeable support layers.