Abstract

A novel three-tier composite membrane based on highly porous nanofibrous substrate was demonstrated for efficient isopropanol dehydration by pervaporation. Here, polyethyleneimine (PEI) modified graphene oxide (GO) sheets were vacuum-assistant assembled onto porous electrospun polyacrylonitrile (PAN) nanofibrous substrate to achieve a smooth, hydrophilic and compact PEI-GO intermediate layer. The introduction of PEI chains endowed GO interlayer with sufficient interaction for bonding adjacent GO nanosheets to enhance stability in water/isopropanol mixture and also with the ascended interlamellar space to improve the water-sorption ability due to the abundant active amino groups. Benefiting from PEI-GO layer, a defect-free sodium alginate (SA) skin layer could be facilely manufactured with elaborately controlled thickness as thin as possible in order to reduce mass transfer resistant and enhance permeability maximally. Meanwhile, the interlayer would also contribute to enhance interfacial adhesion to promote the structure integrity of three-tier thin-film nanofibrous composite (TFNC) membrane in pervaporation dehydration process. After fine-tuning of membrane preparation process, the SA/PEI(75)-GO-60/PAN TFNC membrane exhibited competitive pervaporation performance with the permeate flux of 2009 g/m² h and the separation factor of 1276 operated at 70 °C for dehydration of 90 wt% isopropanol solution. The unique three-tier composite membrane structure suggested an effective and facile approach to design novel membrane structure for further improvement of pervaporation performance.

Graphic Abstract

中文翻译：

---

通过将中间层引入海藻酸钠纳米纤维复合渗透膜中来提高异丙醇的脱水性能

摘要

新型的基于高度多孔的纳米纤维基质的三层复合膜被证明可以有效地通过全蒸发进行异丙醇脱水。在这里，将聚乙烯亚胺（PEI）改性的氧化石墨烯（GO）片真空辅助组装到多孔电纺聚丙烯腈（PAN）纳米纤维基材上，从而获得光滑，亲水和致密的PEI-GO中间层。PEI链的引入赋予GO中间层足够的相互作用，以结合相邻的GO纳米片以增强在水/异丙醇混合物中的稳定性，并由于大量的活性氨基而具有上升的层间空间以提高吸水能力。受益于PEI-GO层，可以容易地制造出无缺陷的海藻酸钠（SA）表层，并精心控制厚度，使其尽可能薄，以降低抗传质性并最大程度地提高渗透性。同时，在全蒸发脱水过程中，中间层还将有助于增强界面粘合性，从而促进三层薄膜纳米纤维复合材料（TFNC）膜的结构完整性。经过膜制备工艺的微调，SA / PEI（75）-GO-60 / PAN TFNC膜表现出有竞争力的渗透性能，渗透通量为2009 g / m 在全蒸发脱水过程中，中间层还将有助于增强界面粘合性，从而促进三层薄膜纳米纤维复合材料（TFNC）膜的结构完整性。经过膜制备工艺的微调，SA / PEI（75）-GO-60 / PAN TFNC膜表现出有竞争力的渗透性能，渗透通量为2009 g / m 在全蒸发脱水过程中，中间层还将有助于增强界面粘合性，从而促进三层薄膜纳米纤维复合材料（TFNC）膜的结构完整性。经过膜制备工艺的微调，SA / PEI（75）-GO-60 / PAN TFNC膜表现出竞争性的渗透性能，渗透通量为2009 g / m²  h，分离系数1276在70°C下进行，以脱水90 wt％的异丙醇溶液。独特的三层复合膜结构提出了一种有效且简便的方法来设计新颖的膜结构，以进一步改善全蒸发性能。

图形摘要