School of Civil and Environmental Engineering, Nanyang Technological University , Singapore 639798, Singapore.
ACS Appl Mater Interfaces. 2014 Sep 24;6(18):16035-48. doi: 10.1021/am503968n. Epub 2014 Sep 5.
With modest temperature demand, low operating pressure, and high solute rejection, membrane distillation (MD) is an attractive option for desalination, waste treatment, and food and pharmaceutical processing. However, large-scale practical applications of MD are still hindered by the absence of effective membranes with high hydrophobicity, high porosity, and adequate mechanical strength, which are important properties for MD permeation fluxes, stable long-term performance, and effective packing in modules without damage. This study describes novel design strategies for highly robust superhydrophobic dual-layer membranes for MD via electrospinning. One of the newly developed membranes comprises a durable and ultrathin 3-dimensional (3D) superhydrophobic skin and porous nanofibrous support whereas another was fabricated by electrospinning 3D superhydrophobic layers on a nonwoven support. These membranes exhibit superhydrophobicity toward distilled water, salty water, oil-in-water emulsion, and beverages, which enables them to be used not only for desalination but also for other processes. The superhydrophobic dual-layer membrane #3S-N with nanofibrous support has a competitive permeation flux of 24.6 ± 1.2 kg m(-2) h(-1) in MD (feed and permeate temperate were set as 333 and 293 K, respectively) due to the higher porosity of the nanofibrous scaffold. Meanwhile, the membranes with the nonwoven support exhibit greater mechanical strength due to this support combined with better long-term performance because of the thicker 3D superhydrophobic layers. The morphology, pore size, porosity, mechanical properties, and liquid enter pressure of water of these superhydrophobic composite membranes with two different structures are reported and compared with commercial polyvinylidene fluoride membranes.
在需要适度的温度、低操作压力和高溶质截留率的情况下，膜蒸馏（MD）是一种有吸引力的海水淡化、废物处理以及食品和制药加工选择。然而，由于缺乏具有高疏水性、高孔隙率和足够机械强度的有效膜，MD 的大规模实际应用仍然受到阻碍，这些特性对于 MD 渗透通量、稳定的长期性能和在模块中无损坏的有效包装都很重要。本研究通过静电纺丝描述了用于 MD 的高度坚固的超疏水双层膜的新设计策略。新开发的膜之一包含耐用且超薄的 3D 超疏水皮层和多孔纳米纤维支撑体，而另一种则是通过在无纺支撑体上静电纺丝 3D 超疏水层来制造。这些膜对蒸馏水、盐水、油包水乳液和饮料表现出超疏水性，这使它们不仅可用于海水淡化，还可用于其他过程。具有纳米纤维支撑体的超疏水双层膜#3S-N 在 MD 中的渗透通量为 24.6±1.2 kg m(-2) h(-1)（进料和渗透温度分别设定为 333 和 293 K），这是由于纳米纤维支架的更高孔隙率所致。同时，由于支撑体的存在，具有无纺支撑体的膜具有更大的机械强度，并且由于较厚的 3D 超疏水层，其具有更好的长期性能。报告了这两种具有不同结构的超疏水复合膜的形态、孔径、孔隙率、机械性能和水的进压，并与商业聚偏二氟乙烯膜进行了比较。
