Abstract The graphene oxide (GO) membrane has recently emerged as a promising material for nanofiltration. However, its application in seawater desalination is limited because of the comparatively low ion rejection performance. The ionisation of the functional groups such as carboxylic acid results in a negative charge on the GO sheet. In this study, molecular dynamics simulations have been conducted to investigate the seawater desalination performance of a bilayer ionised GO membrane with experimentally reported nanocapillary size (10 A) via nanofiltration. The results show that the ionised GO membrane is selective for both Na+ and Cl− ions. Furthermore, this research proposes a method that is more energetically favourable than nanofiltration for enhancing solute rejection by the ionised GO membrane by exposing the membrane to an external electric field opposite to the direction of water flow. The water flux shows a nonmonotonic dependence on the electric field intensity, with solute rejection increasing with an increase in field intensity. At a field intensity of E = 0.6 V/A, a complete rejection of solute can be realized, with a water flux as high as 0.071 kg/cm2/s. The findings from this study will be helpful for promoting GO as a novel material for seawater desalination membranes.

中文翻译：

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用于海水淡化的电离氧化石墨烯膜

摘要 氧化石墨烯 (GO) 膜最近已成为一种有前途的纳滤材料。然而，由于离子排斥性能相对较低，其在海水淡化中的应用受到限制。官能团（如羧酸）的电离导致 GO 片上带负电荷。在这项研究中，已经进行了分子动力学模拟来研究双层电离 GO 膜的海水淡化性能，通过纳米过滤实验报告了纳米毛细管尺寸 (10 A)。结果表明离子化的 GO 膜对 Na+ 和 Cl- 离子都有选择性。此外，这项研究提出了一种比纳滤在能量上更有利的方法，通过将膜暴露于与水流方向相反的外部电场来增强离子化 GO 膜对溶质的排斥。水通量显示出对电场强度的非单调依赖性，溶质排斥随电场强度的增加而增加。在 E = 0.6 V/A 的场强下，可以实现完全排斥溶质，水通量高达 0.071 kg/cm2/s。这项研究的结果将有助于促进 GO 作为海水淡化膜的新型材料。在 E = 0.6 V/A 的场强下，可以实现完全排斥溶质，水通量高达 0.071 kg/cm2/s。这项研究的结果将有助于促进 GO 作为海水淡化膜的新型材料。在 E = 0.6 V/A 的场强下，可以实现完全排斥溶质，水通量高达 0.071 kg/cm2/s。这项研究的结果将有助于促进 GO 作为海水淡化膜的新型材料。