Water desalination: Graphene cleans up water.
Water desalination: Graphene cleans up water.
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DOI：
10.1038/nnano.2012.153
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发表时间：
2012-09
影响因子：
38.3
通讯作者：
E. Wang;R. Karnik
中科院分区：
文献类型：
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作者：
E. Wang;R. Karnik
人口的快速增长、工业化和城市化使清洁水成为日益稀缺的资源，而海水淡化代表了一种有前途的解决方案1。反渗透占世界已安装海水淡化能力的近一半，其工作原理是在高压下驱动盐水（给水）穿过半透膜。该膜允许水分子通过，但不允许盐离子通过。反渗透比其他海水淡化技术更节能，并且已经投入工业发展数十年，但面临膜污染和水输送缓慢的问题。需要新的膜材料来解决这些问题。现在，麻省理工学院的 David Cohen-Tanugi 和 Jeffrey Grossman 在《Nano Letters》上撰文计算出，具有亚纳米孔的石墨烯可以超过当前聚合物反渗透膜的透水性两到三个数量级，使其成为用于海水淡化的高性能膜。 2.最先进的聚合物反渗透膜依赖于溶液扩散机制，其中水分子被选择性地吸收到膜表面的薄层中。膜，然后扩散到另一侧。聚合物膜具有出色的脱盐率，但水通过无序聚合物的扩散传输很慢。因此，最近的研究重点是通过纳米结构膜中的分子筛分来提高水通量，该纳米结构膜具有刚性、明确的尺寸选择性孔，例如碳纳米管 3 或沸石 4。然而，这些膜难以以可扩展和低成本的方式制造，并且迄今为止表现出有限的性能。特别是，用于膜的最小碳纳米管仍然太大，无法有效排除盐离子，而薄而连续的沸石层的制造则极具挑战性。
Rapid population growth, industrialization and urbanization have made clean water an increasingly scarce resource, and water desalination represents one promising solution 1. Reverse osmosis accounts for nearly half of the world's installed desalination capacity, and works by driving salt (feed) water across a semi-permeable membrane under high pressure. The membrane allows water molecules to pass through, but not salt ions. Reverse osmosis is more energy efficient than other desalination technologies, and has been in industrial development for several decades, but struggles with membrane fouling and slow water transport. New membrane materials are needed to address these issues. Now, writing in Nano Letters, David Cohen-Tanugi and Jeffrey Grossman at the Massachusetts Institute of Technology have calculated that graphene with subnanometre pores can surpass the water permeability of current polymeric reverse osmosis membranes by two to three orders of magnitude, making it a high-performance membrane for water desalination 2.State-of-the-art polymeric reverse osmosis membranes rely on the solution-diffusion mechanism, in which water molecules are selectively absorbed into a thin layer at the surface of the membrane and then diffuse across to the other side. Polymeric membranes offer excellent salt rejection, but the diffusive transport of water through the disordered polymer is slow. Recent research has therefore focused on increasing water throughput by molecular sieving in nanostructured membranes with rigid, well-defined size-selective pores such as carbon nanotubes 3 or zeolites 4. These membranes, however, are difficult to manufacture in a scalable and low-cost fashion, and have thus far demonstrated limited performance. In particular, the smallest carbon nanotubes used for membranes are still too large to effectively exclude salt ions, while the fabrication of thin, continuous zeolite layers is exceptionally challenging.