Currently, polymeric membranes dominate the desalination market because they exhibit high water flux and salt rejection rates. Especially, polymeric membranes used in reverse osmosis (RO) are typically polyamide (PA) thin-film composites (TFCs); these membranes are selected primarily because of their high water permeability and relative impermeability to various dissolved impurities such as salt ions and other small molecules as well as chemical stability in a broad pH range. Since ultrafast water transport through carbon nanotubes (CNT) was reported, a number of studies have been performed to prepare large-scale CNT-based membranes for water purification as well as desalination, particularly focusing on high flux membranes, surpassing current polymeric water purification and desalination membranes. Ideally, vertically-aligned CNT membranes are preferred to maximize the advantages of ultrahigh water flux through CNT, but they still suffer from lack of scalability and low salt rejection due to relatively larger diameter of currently available CNT. Alternatively, mixed matrix system, that is, CNT-embedded polymeric desalination membranes could be a more practical way to obtain scalable CNT-based membranes with much enhanced water flux without significant loss of salt rejection for energy-saving desalination process. Similar to other nanomaterials, however, CNT tends to aggregate in polymeric matrix without any surface modification, leading to poor membrane performance due to the formation of unfavorable large voids. Here we show that highly dispersed CNT in selective PA layer and/or polymeric substrate membranes can be prepared by introducing a hydrophilic modified CNT, leading to much higher water flux as well as high salt rejection. In this study, we report overall preparation processes of high flux CNT-embedded PA TFCs and envision challenging issues and perspective for its actual application in desalination.<br/> <br/>

Carbon nanotubes-embedded, high-permeable polyamide thin-film composite membranes for desalination

253rd National Meeting (2017)

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