Ultrafast permeation of water through protein-based membranes
Ultrafast permeation of water through protein-based membranes
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DOI：
10.1038/nnano.2009.90
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发表时间：
2009-06-01
影响因子：
38.3
通讯作者：
Ichinose, Izumi
中科院分区：
文献类型：
--
作者：
Peng, Xinsheng;Jin, Jian;Ichinose, Izumi
通过多孔膜的压力驱动过滤广泛用于从地下水和地表水生产饮用水（1-3）。渗透理论预测，过滤速率与过滤膜两端的压差成正比，与膜的厚度成反比（4）。然而，这些膜需要能够承受高的水通量和压力，这意味着商业过滤系统中的活性分离层通常具有几十到几百纳米的厚度（5）。过滤性能可以通过使用多孔硅膜（6）或固定在氮化硅（7）或聚合物膜（8，9）中的碳纳米管来改善，但是这些结构难以制造。在这里，我们报告了一种由交联蛋白质制成的新型过滤膜，该膜具有机械稳定性，并且含有直径小于2.2 nm的通道。我们发现，60 nm厚的膜可以从高达9，000 l h（-1）m（-2）bar（-1）的通量中浓缩水性染料，这比具有类似截留性能的商业过滤膜可以承受的通量高1，000倍（1，10，11）。基于这些结果和分子动力学模拟，我们提出，有效长度小于5.8 nm的蛋白质包围的通道可以分离染料分子，同时允许水在小于1 bar的压力下超快渗透。
Pressure-driven filtration by porous membranes is widely used in the production of drinking water from ground and surface water(1-3). Permeation theory predicts that filtration rate is proportional to the pressure difference across the filtration membrane and inversely proportional to the thickness of the membrane(4). However, these membranes need to be able to withstand high water fluxes and pressures, which means that the active separation layers in commercial filtration systems typically have a thickness of a few tens to several hundreds of nanometres(5). Filtration performance might be improved by the use of ultrathin porous silicon membranes(6) or carbon nanotubes immobilized in silicon nitride(7) or polymer films(8,9), but these structures are difficult to fabricate. Here, we report a new type of filtration membrane made of crosslinked proteins that are mechanically robust and contain channels with diameters of less than 2.2 nm. We find that a 60-nm-thick membrane can concentrate aqueous dyes from fluxes up to 9,000 l h(-1) m(-2) bar(-1), which is similar to 1,000 times higher than the fluxes that can be withstood by commercial filtration membranes with similar rejection properties(1,10,11). Based on these results and molecular dynamics simulations, we propose that protein-surrounded channels with effective lengths of less than 5.8 nm can separate dye molecules while allowing the ultrafast permeation of water at applied pressures of less than 1 bar.