Abstract The major challenge in membrane distillation for seawater desalination and/or wastewater purification is the development of high-efficiency membrane distillation (MD) membranes with high porosity, hydrophobicity, and adequate mechanical strength for long-term operation. Herein, a superhydrophobic two-tier interlocked composite membrane based on a hierarchically structured isotactic polypropylene (iPP) coating and an electrospun poly(vinylidene fluoride) (PVDF) nanofibrous support was engineering constructed. The obtained coating layer possessed a deformed micro/nanostructured microsphere surface with robust superhydrophobicity and further glorious anti-fouling property, which was owed to the synergistic effect of the low surface free energy material and hierarchical roughness. Specially, the middle transitional interlocking zone between the crystalline iPP microsphere coating and PVDF nanofibers endowed the resultant composite membrane with excellent structural integrity including the remarkable enhancement in mechanical performance compared with PVDF flat sheet or nanofibrous membranes, and also resulted in the iPP/PVDF composite membranes with robust durability against ultrasonication in isopropanol and strong acid/base attacks. Moreover, for the simulated high salinity sunset yellow (SY) wastewater, the optimized superhydrophobic composite membrane exhibited a competitive permeate flux of 53.9 kg/(m2·h) and complete rejection over 50 h operation (ΔT = 40 °C) because of its highly porous nanofibrous support and firmly sustainable liquid repellency.

中文翻译：

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膜蒸馏联锁结构坚固超疏水两层复合膜的工程构建

摘要 用于海水淡化和/或废水净化的膜蒸馏的主要挑战是开发具有高孔隙率、疏水性和足够机械强度以供长期运行的高效膜蒸馏 (MD) 膜。在此，基于分层结构的全同立构聚丙烯 (iPP) 涂层和电纺聚偏二氟乙烯 (PVDF) 纳米纤维支撑的超疏水两层互锁复合膜被工程构建。由于低表面自由能材料和分级粗糙度的协同作用，获得的涂层具有变形的微/纳米结构微球表面，具有强大的超疏水性和更优异的防污性能。特别，结晶 iPP 微球涂层和 PVDF 纳米纤维之间的中间过渡互锁区赋予所得复合膜优异的结构完整性，包括与 PVDF 平板或纳米纤维膜相比机械性能显着增强，并且还导致 iPP/PVDF 复合膜具有对异丙醇中的超声波处理和强酸/碱腐蚀具有强大的耐用性。此外，对于模拟的高盐度日落黄 (SY) 废水，优化的超疏水复合膜表现出 53.9 kg/(m2·h) 的有竞争力的渗透通量，并且在 50 小时的运行 (ΔT = 40 °C) 内完全截留，因为它具有高度多孔的纳米纤维支撑和牢固可持续的拒液性。