School of Civil and Environmental Engineering, Nanyang Technological University , 639798 Singapore.
Environ Sci Technol. 2014 Jun 3;48(11):6335-41. doi: 10.1021/es405795s. Epub 2014 May 13.
The practical application of membrane distillation (MD) for water purification is hindered by the absence of desirable membranes that can fulfill the special requirements of the MD process. Compared to the membranes fabricated by other methods, nanofiber membranes produced by electrospinning are of great interest due to their high porosity, low tortuosity, large surface pore size, and high surface hydrophobicity. However, the stable performance of the nanofiber membranes in the MD process is still unsatisfactory. Inspired by the unique structure of the lotus leaf, this study aimed to develop a strategy to construct superhydrophobic composite nanofiber membranes with robust superhydrophobicity and high porosity suitable for use in MD. The newly developed membrane consists of a superhydrophobic silica-PVDF composite selective skin formed on a polyvinylidene fluoride (PVDF) porous nanofiber scaffold via electrospinning. This fabrication method could be easily scaled up due to its simple preparation procedures. The effects of silica diameter and concentration on membrane contact angle, sliding angle, and MD performance were investigated thoroughly. For the first time, the direct contact membrane distillation (DCMD) tests demonstrate that the newly developed membranes are able to present stable high performance over 50 h of testing time, and the superhydrophobic selective layer exhibits excellent durability in ultrasonic treatment and a continuous DCMD test. It is believed that this novel design strategy has great potential for MD membrane fabrication.
膜蒸馏（MD）在净水方面的实际应用受到缺乏理想膜的阻碍，这些理想膜需要满足 MD 过程的特殊要求。与其他方法制造的膜相比，静电纺丝制备的纳米纤维膜因其高孔隙率、低曲折度、大表面孔径和高表面疏水性而备受关注。然而，纳米纤维膜在 MD 过程中的稳定性能仍不尽如人意。受荷叶独特结构的启发，本研究旨在开发一种构建具有稳定超疏水性和高孔隙率的超疏水复合纳米纤维膜的策略，该膜适用于 MD。新开发的膜由聚偏二氟乙烯（PVDF）多孔纳米纤维支架上形成的超疏水二氧化硅-PVDF 复合选择性皮层组成，通过静电纺丝制备而成。由于其简单的制备程序，这种制造方法很容易扩大规模。详细研究了二氧化硅直径和浓度对膜接触角、滑动角和 MD 性能的影响。首次通过直接接触膜蒸馏（DCMD）测试表明，新开发的膜在 50 小时的测试时间内能够呈现稳定的高性能，超疏水选择性层在超声处理和连续 DCMD 测试中表现出优异的耐久性。相信这种新颖的设计策略在 MD 膜制备方面具有巨大的潜力。
