Freestanding self-assembled sulfonated pentablock terpolymer membranes for high flux pervaporation desalination
Freestanding self-assembled sulfonated pentablock terpolymer membranes for high flux pervaporation desalination
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DOI：
10.1016/j.memsci.2020.118460
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发表时间：
2020-11
影响因子：
9.5
通讯作者：
Elisabeth R. Thomas;Amit Jain;Stewart C. Mann;Yi Yang;Matthew D. Green;W. Walker;F. Perreault;Mary Laura Lind;R. Verduzco
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文献类型：
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作者：
Elisabeth R. Thomas;Amit Jain;Stewart C. Mann;Yi Yang;Matthew D. Green;W. Walker;F. Perreault;Mary Laura Lind;R. Verduzco
渗透蒸发脱盐与竞争性脱盐技术相比具有几个优点，最显著的是选择挥发性有机化合物或不选择挥发性有机化合物的能力以及在低跨膜压力下处理高盐度进料的能力。由于其能量强度，渗透蒸发尚未商业化用于脱盐应用。然而，诸如水力压裂的新兴工艺产生高总溶解固体（>30-45 g L-1）的副产物流，其超过传统反渗透的操作极限并且可以通过渗透蒸发处理。在这里，我们展示了具有优异渗透性和高盐去除率的自立式渗透蒸发膜，其基于具有商品名Nexar™的部分磺化的五嵌段共聚物。渗透蒸发膜很容易从这种材料铸造的脱盐性能相当或上级的商业可用的膜。我们发现，聚合物的磺化度和铸膜溶剂的极性对膜的吸水率有显着的影响，但对渗透蒸发脱盐性能的影响不大。磺化度为52%（2.0 meq g− 1 IEC）的膜和由50 wt%正丙醇和50 wt%甲苯组成的铸膜溶液在室温下从32 g L− 1氯化钠进料溶液中渗透蒸发时实现了3.32 kg m− 2 h −1的水通量（渗透率135 kg m− 2 h −1bar−1）和99.5%的盐去除。我们证明了致密的无孔Nexar™渗透蒸发膜的渗透性和盐分离性能上级于商业渗透蒸发膜并且等同于具有大得多的孔的商业膜蒸馏膜。该研究表明，市售磺化五嵌段三元共聚物是优良的渗透蒸发脱盐膜，因为它们易于铸造和优异的性能。
Pervaporation desalination has several advantages over competing desalination technologies, most notably an ability to select for or against volatile organic compounds and the ability to process high salinity feeds at a low transmembrane pressure. Pervaporation has not been commercialized for desalination applications because of its energy intensity. However, emerging processes such as hydraulic fracturing produce high total dissolved solids (>30–45 g L−1) byproduct streams that exceed the operational limits of traditional reverse osmosis and could be treated by pervaporation. Here, we demonstrate free-standing pervaporation membranes with excellent permeance and high salt removal based on a partially sulfonated pentablock terpolymer with the tradename Nexar™. Pervaporation membranes were easily cast from this material with desalination performances comparable or superior to commercially available membranes. We found that the polymer degree of sulfonation and casting solvent polarity had a significant impact on the membranes’ water uptake but only a modest impact on the pervaporation desalination performance. Membranes with a degree of sulfonation of 52% (2.0 meq g−1IEC) and a casting solution composed of 50 wt%n-propanol and 50 wt% toluene achieved a water flux of 3.32 kg m−2h−1(permeance 135 kg m−2h−1bar−1) with 99.5% salt removal in pervaporation from a 32 g L−1sodium chloride feed solution at room temperature. We demonstrated that dense, non-porous Nexar™ pervaporation membrane permeance and salt separation performance were superior to commercial pervaporation membranes and equivalent to commercial membrane distillation membranes, which have much larger pores. This study demonstrates that commercially available sulfonated pentablock terpolymers are excellent membranes for pervaporation desalination because of their ease of casting and excellent performance.