Abstract Hydrophobic membranes suffer from wetting and scaling when treating hypersaline brine using membrane distillation (MD). Thus omniphobic membranes with re-entrant surfaces have been developed by diverse modifications to enhance anti-wetting/scaling properties. However, those post-modifications usually sacrifice membrane permeability in spite of improved stability. In this work, omniphobic membranes were fabricated by decorating polyvinylidene fluoride (PVDF) nanofibrous membranes with different silica nanoparticles (SiNPs) followed by fluorination. Compared to unmodified nanofibrous and commercial PVDF membranes, both smaller SiNPs coated membrane #P-Min and larger SiNPs coated membrane #P-Max can perfectly sustain liquids with low surface tensions on their surfaces without wetting. In contrast to #P-Max with an oil contact angle of 136 ± 1°, #P-Min exhibited better oleophobicity with an oil contact angle of 152 ± 1°. In addition, the rigidity of their omniphobic properties was confirmed by testing in harsh conditions. Moreover, #P-Min successfully overcame the trade-off relation between membrane permeability and rejection with an enhanced MD flux due to more effective water evaporation area on membrane surface and a higher membrane porosity. While #P-Max was wetted by a hypersaline feed solution composed of 25 wt% NaCl, #P-Min could maintain a stable flux of 15 L m−2h−1 in a continuous 7-h MD operation, which proved its excellent performance for brine treatment. Furthermore, #P-Min exhibited less scaling tendency when feed was a saturated gypsum solution. Compared to #P-Max, the better anti-scaling properties of #P-Min should be due to its higher surface energy barrier, better slippery property and less solid-liquid contact area, which effectively impede crystal nucleation and attachment.

中文翻译：

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不同二次纳米级粗糙度对膜蒸馏法处理盐水全疏膜性能的影响

摘要 在使用膜蒸馏 (MD) 处理高盐盐水时，疏水膜会遭受润湿和结垢。因此，已经通过多种修改开发了具有凹入表面的全疏水膜，以增强抗润湿/结垢性能。然而，尽管提高了稳定性，但那些后修饰通常会牺牲膜渗透性。在这项工作中，通过用不同的二氧化硅纳米粒子 (SiNPs) 装饰聚偏二氟乙烯 (PVDF) 纳米纤维膜然后氟化来制造全疏水膜。与未改性的纳米纤维膜和商用 PVDF 膜相比，较小的 SiNPs 涂层膜 #P-Min 和较大的 SiNPs 涂层膜 #P-Max 都可以完美地维持表面具有低表面张力的液体而不会润湿。与油接触角为 136 ± 1° 的 #P-Max 相比，#P-Min 表现出更好的疏油性，油接触角为 152 ± 1°。此外，通过在恶劣条件下进行的测试，证实了其全疏水性的刚性。此外，由于膜表面更有效的水蒸发面积和更高的膜孔隙率，#P-Min 成功地克服了膜渗透性和截留率之间的权衡关系，提高了 MD 通量。虽然#P-Max 被由 25 wt% NaCl 组成的高盐度进料溶液润湿，但#P-Min 在连续 7 小时 MD 操作中可以保持 15 L m-2h-1 的稳定通量，这证明了其优异的性能用于盐水处理。此外，当进料是饱和石膏溶液时，#P-Min 表现出较小的结垢趋势。与#P-Max相比，