Molecular Dynamics Simulation of Monolayer Fullerene Membranes for Desalination
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摘要: 海水淡化是最有希望解决全球淡水资源短缺的有效方案之一,纳米技术的进步推动了各类用于水净化的纳米多孔膜的发展. 理论和实验研究发现了纳米多孔石墨烯的超高水透过和盐离子拒绝率. 然而精确创建、控制纳米级孔隙的大小和分布的操作难度极大地限制了纳米膜材料的实际化应用. 通过分子动力学模拟发现具有均匀有序纳米孔排列准四边形结构(quasi-tetragonal phase, qTP)的单层富勒烯(C60)薄膜在海水淡化方面的巨大潜力,在保证100%阻盐率的同时,与传统聚合物过滤膜相比,单层富勒烯薄膜展示出卓越的透水性. 从原子尺度系统地研究了单层富勒烯薄膜结构的筛分机制,发现钠离子、氯离子与水分子相比,在穿膜运输过程中有大的能量障碍. 结果表明,单层富勒烯薄膜是一种很有优势的海水淡化膜.Abstract: Seawater desalination is one of the most promising solutions to fresh water shortage all over the world. The rapid development of nanotechnology led to the boom of nanoporous membranes for water purification. Recent theoretical and experimental studies reported ultra-high water permeability and salt rejection in nanoporous monolayer graphene. However, the difficulty of precisely creating nanometer-scale pores and controlling their distribution greatly limits its industrial application. Through molecular dynamics (MD) simulation, the monolayer quasi-tetragonal phase fullerene (qTPC60) was found to have tremendous potential as ultra-permeable membranes for desalination due to their unform pore distribution. The monolayer fullerene membranes exhibit high water permeability compared to conventional polymer filtration membranes. The work offers insights into the molecular mechanism of sieving, and the MD simulations show that Na+ and Cl- ions have large energy barriers. This 2D monolayer carbon material with unique structure exhibits great potential in seawater desalination.
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Key words:
- seawater desalination /
- monolayer fullerene /
- water permeability /
- ion rejection /
- molecular dynamics
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表 1 离子、水分子(SPC/E)和C60的LJ参数以及电荷信息
Table 1. The LJ parameters and partial charges for ions, water molecules (SPC/E), and carbon atoms of C60 and graphene
site σ/nm ε/(kcal/mol) q/e ion Na+ 0.333 0.002 772 1.0 Cl- 0.442 0.117 8 -1.0 water H 0 0 0.423 8 O 0.317 0.153 5 -0.847 6 C60 C 0.340 0.086 0 graphene C 0.340 0.086 0 表 2 第一、第二水化壳层在体相水、qTPC60内部的配位数以及相应脱水数目
Table 2. Coordination numbers in the 1st and 2nd hydration shells and reduced numbers
Bulk N qTPC60 N reduced number Nr Nc1 5.6 2.0 3.6 Nc2 17.1 3.2 13.9 -
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