NSF/DMR-BSF: Understanding transport in biomimetic carbon nanotube porin membranes for water treatment and osmotic energy harvesting

非技术：虽然世界上大部分是由水组成的，但人类消费的水几乎总是需要在使用前进行某种形式的净化。鉴于全球需求不断增加，获得清洁水是一个世界性的问题，需要新的技术以降低成本来满足需求。由于海洋仍然是唯一真正取之不尽用之不竭的水源，反渗透海水淡化将仍然是美国和其他地区可持续水解决方案的重要组成部分。此外，在淡水资源稀缺的地方，如以色列、中东或美国西部，海水淡化成为一个关键组成部分。虽然海水淡化解决方案已经在市场上出现了50多年，但大多数商业反渗透海水淡化装置仍然依赖于几十年前的膜技术，这种技术可能在几年前就已经达到了它的实用极限。在这个美国和以色列的联合项目中，研究人员将开发一种新型膜，通过让水分子穿过直径小于人类头发百万分之一的非常小的碳纳米管，有效、快速地从水中去除盐分。纳米管不仅体积小，而且效率极高，通过水的速度比任何已知的孔都要快。拟议的研究还将采用一种完全不同的方法，模仿最好的生物膜（活细胞的外膜）的结构，并将在水净化方面比现有的细胞膜有重大改进。这项调查的一个重要部分将包括向本科生和K-12学生宣传水技术的重要性，培训美国和以色列的研究生掌握最先进的仿生技术，并建立一个美以联合暑期学校，让学生们可以向全球水净化研究的领导者学习。技术方面：这个合作项目汇集了两个美国的生物材料/纳米孔研究组（Noy, Wanunu）和一个以色列的膜科学研究组（freeger），将开发一个强大的仿生膜平台，模仿细胞膜的分层组织，并利用碳纳米管孔的高效和选择性运输。具体来说，由碳纳米管孔（CNTPs）组成的膜将被设计和制造，这些孔嵌入在一层薄薄的基质层中，并置于可渗透膜支撑上。这些成分模拟了细胞膜的三个主要结构元素：(i)膜孔通道，（ii）脂质双分子层和（iii）细胞骨架。本研究将在整体和单孔尺度上表征水和离子在这些膜中的传输，主要关注纳米孔限制实现高效和选择性传输的物理原理。本研究还将使用化学修饰来改变碳纳米管孔的选择性。这些膜应该能够增强膜的性能，用于反渗透（RO）水净化和使用反电渗析（RED）的渗透发电。它们还将使我们能够探索现代膜科学中的基本问题，例如水传输和离子排斥的物理性质，纳米孔中的约束作用，固定电荷的影响以及浓度极化所施加的限制。最后，本项目的外联工作将使我们能够强调基础研究和颠覆性技术进步对确保未来获得清洁水的重要性。这将通过a)建立一个美国-以色列联合暑期学校来实现，该学校将专注于新的水技术和水相关科学的基础知识，b)培训美国研究生和本科生在全球背景下进行水研究。

Non-Technical: While most of the world is made up of water, water for human consumption nearly always requires some form of purification before use. Given the ever-increasing global demand, access to clean water is a world-wide problem that requires novel technologies to keep up with demand at reduced costs. Since the ocean remains the only truly inexhaustible water source, reverse osmosis seawater desalination will remain a vital component of a sustainable water solution in the US and beyond. Moreover, in places with scarce freshwater resources, such as Israel, Middle East, or Western US, desalination becomes a critical component. While desalination solutions have been on the market for more than 50 years, most of commercial reverse osmosis desalination installations still rely on decades-old membrane technology that has likely reached its useful limit years ago. In this joint US/Israel project, the investigators will develop a new kind of membrane that efficiently and quickly removes salt from water by passing water molecules through very small carbon nanotubes with diameters less than one-millionth of a human hair. Nanotubes are not only small, but also extraordinarily efficient, passing water faster than any other known pore. The propose studies also will take a radically-different approach that imitates the structure of the best membrane biological membrane 'the outer membrane of a live cell' and should deliver significant improvements over existing cell membranes for water purification. A vital part of this investigation will involve educational outreach to undergraduate and K-12 students on the importance of water technologies, training US and Israeli graduate students in the state of the art biomimetic technologies, and developing a joint US-Israel summer school in which the students can learn from global leaders in water purification research.Technical: This collaborative project, which brings together two US-based biomaterials/nanopores groups (Noy, Wanunu) and an Israeli membrane science group (Freger), will develop a robust biomimetic membrane platform that mimics hierarchical organization of a cell membrane and exploits highly-efficient and selective transport in carbon nanotube porins. Specifically, membranes that comprise carbon nanotube porins (CNTPs) embedded in a thin matrix layer resting on a permeable membrane support will be designed and fabricated. These components mimic the three main structural elements of a cell membrane: (i) membrane pore channels, (ii) lipid bilayer, and (iii) cytoskeleton. This study will characterize water and ion transport in these membranes on ensemble and single-pore scales, focusing mainly on the physical principles by which nanopore confinement enables efficient and selective transport. This research will also use chemical modification to alter selectivity of the carbon nanotube porins. These membranes should enable enhanced membrane performance for reverse osmosis (RO) water purification and osmotic power generation using reverse electrodialysis (RED). They will also allow us to explore fundamental questions in modern membrane science, such as the physics of water transport and ion exclusion, the role of confinement in nanopores, effects of fixed charges, and limitations imposed by concentration polarization. Finally, outreach efforts in this project will allow us to highlight the importance of basic research and disruptive technological advances for ensuring future availability of clean water. This will be achieved through a) creation of a joint US-Israel summer school that would be focused on new water technologies and fundamentals of water-related science, b) training US graduate and undergraduate students about water research in the global context.