Abstract Membrane distillation (MD) is an emerging water treatment technology suitable for hypersaline wastewater. However, membrane wetting is a primary obstacle to restrict its widespread industrial use. In this study, a superhydrophobic nanofibrous membrane (labeled as FZP) with high water contact angle of 162.3° and sliding angle of 9.8° was fabricated through fluorinating of zinc oxide (ZnO) blended electrospun polyvinylidene fluoride (PVDF) membrane. In comparison with neat and ZnO blended PVDF (ZP) nanofibrous membranes, FZP membrane has much better anti-wetting property due to its superhydrophobicity and higher liquid entry pressure (LEP) value when desalinating both pure NaCl solution and NaCl solutions with low-surface-tension sodium dodecyl sulfate (SDS) and sparingly soluble salt CaSO4. LEP values of membranes for SDS and CaSO4 contained feed solutions were calculated to be smaller than that for pure NaCl solution, accelerating the occurrence of membrane wetting. Temperature gradient across the membrane and Gibbs free energies of CaSO4 heterogeneous nucleation were further calculated to elucidate the wetting mechanism. Our results provide valuable insights for better developing superhydrophobic membrane and understanding its anti-wetting property in MD process.

中文翻译：

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超疏水 PDTS-ZnO-PVDF 膜的制备及其在直接接触膜蒸馏 (DCMD) 应用中的抗润湿分析

摘要 膜蒸馏（MD）是一种新兴的适用于高盐度废水的水处理技术。然而，膜润湿是限制其广泛工业应用的主要障碍。在这项研究中，通过氧化锌 (ZnO) 共混电纺聚偏二氟乙烯 (PVDF) 膜的氟化制备了一种具有 162.3° 高水接触角和 9.8° 滑动角的超疏水纳米纤维膜（标记为 FZP）。与纯和 ZnO 混合 PVDF (ZP) 纳米纤维膜相比，FZP 膜在对纯 NaCl 溶液和具有低表面积的 NaCl 溶液进行脱盐时，由于其超疏水性和更高的液体进入压力 (LEP) 值，因此具有更好的抗湿性十二烷基硫酸钠 (SDS) 和微溶盐 CaSO4。经计算，含 SDS 和 CaSO4 进料溶液的膜的 LEP 值小于纯 NaCl 溶液的 LEP 值，加速了膜润湿的发生。进一步计算膜上的温度梯度和 CaSO4 异相成核的吉布斯自由能以阐明润湿机制。我们的研究结果为更好地开发超疏水膜和了解其在 MD 过程中的抗湿性能提供了宝贵的见解。