Department of Chemical and Environmental Engineering , Yale University , New Haven , Connecticut 06520-8286 , United States.
Environ Sci Technol. 2018 Sep 18;52(18):10737-10747. doi: 10.1021/acs.est.8b03426. Epub 2018 Aug 27.
Reverse osmosis (RO) has become a premier technology for desalination and water purification. The need for increased selectivity has incentivized research into novel membranes, such as biomimetic membranes that incorporate the perfectly selective biological water channel aquaporin or synthetic water channels like carbon nanotubes. In this study, we consider the performance of composite biomimetic membranes by projecting water permeability, salt rejection, and neutral-solute retention based on the permeabilities of the individual components, particularly the water channel, the amphiphilic bilayer matrix, and potential support layers that include polymeric RO, nanofiltration (NF), and porous ultrafiltration membranes. We find that the support layer will be crucial in the overall performance. Selective, relatively low-permeability supports minimize the negative impact of defects in the biomimetic layer, which are currently the main performance-limiting factor for biomimetic membranes. In particular, RO membranes as support layers would enable >99.85% salt rejection at ∼10000-fold greater biomimetic-layer defect area than for porous supports. By fundamentally characterizing neutral-solute permeation through RO and NF membranes, we show that RO membranes as support layers would enable high rejection of organic pollutants based on molecular size, overcoming the rapid permeation of hydrophobic solutes through the biomimetic layer. A biomimetic membrane could also achieve exceptionally high boron rejections of ∼99.7%, even with 1% defect area in the biomimetic layer. We conclude by discussing the implications of our findings for biomimetic membrane design.
反渗透（RO）已成为海水淡化和水净化的主要技术。对更高选择性的需求促使人们研究新型膜，例如仿生膜，其中包含具有完美选择性的生物水通道水通道蛋白或合成水通道，如碳纳米管。在这项研究中，我们通过预测水透过率、盐排斥率和中性溶质保留率来考虑复合仿生膜的性能，这些预测基于各个组件的渗透性，特别是水通道、两亲性双层基质以及潜在的支撑层，这些支撑层包括聚合物 RO、纳滤（NF）和多孔超滤膜。我们发现支撑层将是整体性能的关键。选择性、相对低渗透性的支撑层将最大限度地减少仿生层缺陷的负面影响，目前这是仿生膜的主要性能限制因素。特别是，RO 膜作为支撑层，将能够在比多孔支撑层大约 10000 倍的仿生层缺陷面积下，实现＞99.85%的盐排斥率。通过从根本上表征 RO 和 NF 膜中中性溶质的渗透，我们表明，RO 膜作为支撑层将能够基于分子大小实现对有机污染物的高排斥率，克服疏水分子通过仿生层的快速渗透。即使在仿生层中存在 1%的缺陷面积，仿生膜也可以实现高达约 99.7%的硼排斥率。最后，我们讨论了我们的发现对仿生膜设计的影响。
