Growing interests have been shown on the application of vacuum membrane distillation (VMD) for desalination and concentrated effluent treatment due to its high mass transfer efficiency. However, VMD is more prone to severe membrane wetting, potentially due to the high-pressure difference across the membrane. Anti-wetting strategies such as frequent cleaning to remove the crystals and surface modification of the membrane to improve the intrinsic anti-wetting property are often investigated. The usual approach to enhance the surface hydrophobicity is to introduce a nanostructured surface or/and to reduce the surface energy by functionalisation. This work demonstrated a facile process to introduce a superhydrophobic layer on polypropylene hollow fiber membranes via a mussel-inspired modification technique. The membranes were deposited by polydopamine/polyethyleneimine, followed by the surface silicification and subsequent fluorination. We examined the surface morphologies, chemistry and wettability after each step of surface modification. The surface functional coating is ultrathin, which imposed a negligible effect on the membrane pore size. The final modified membranes exhibited comparable mass transfer with the virgin membrane, but superior wetting resistance in 35g/L NaCl solution for long term operation with the permeate conductivity < 10µS/cm for 50h. It also showed excellent cleaning efficiency in the long-term treatment of brackish groundwater concentrate.

中文翻译：

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通过易于生物启发的矿化作用形成的超疏水膜，用于真空膜蒸馏

由于真空膜蒸馏（VMD）的传质效率高，因此在将其用于脱盐和浓缩废水处理中的应用日益引起人们的关注。但是，VMD更容易发生严重的膜润湿，这可能是由于跨膜的高压差所致。经常研究抗湿润策略，例如经常清洗以除去晶体和对膜进行表面改性以提高固有的抗湿润性能。增强表面疏水性的常用方法是引入纳米结构表面或/和通过官能化降低表面能。这项工作证明了一种简便的方法，可通过贻贝启发的改性技术在聚丙烯中空纤维膜上引入超疏水层。通过聚多巴胺/聚乙烯亚胺沉积膜，随后进行表面硅化和随后的氟化。在表面改性的每个步骤之后，我们检查了表面形态，化学性质和润湿性。表面功能涂层超薄，对膜孔径的影响可忽略不计。最终的改性膜表现出与原始膜相当的传质，但是对于长期操作而言，在35g / L NaCl溶液中具有优异的耐湿性，且渗透率＜3。10µS / cm持续50h。在微咸的地下水浓缩液的长期处理中，它还显示出优异的清洁效率。表面改性的每个步骤后的化学性质和润湿性。表面功能涂层超薄，对膜孔径的影响可忽略不计。最终的改性膜表现出与原始膜相当的传质，但是对于长期操作而言，在35g / L NaCl溶液中具有优异的耐湿性，且渗透率＜3。10µS / cm持续50h。在微咸的地下水浓缩液的长期处理中，它还显示出优异的清洁效率。表面改性的每个步骤后的化学性质和润湿性。表面功能涂层超薄，对膜孔径的影响可忽略不计。最终的改性膜表现出与原始膜相当的传质，但是对于长期操作而言，在35g / L NaCl溶液中具有优异的耐湿性，且渗透率＜3。10µS / cm持续50h。在微咸的地下水浓缩液的长期处理中，它还显示出优异的清洁效率。