Tan Qiong, Fan Yan, Song Zailing, Chen Junlang, Chen Liang
Department of Optical Engineering, College of Optical, Mechanical and Electrical Engineering, Zhejiang A&F University, Linan, 311300, Hangzhou, China.
J Mol Model. 2022 Feb 8;28(3):57. doi: 10.1007/s00894-022-05045-7.
Graphene oxide (GO) membranes have shown great potential in the applications of water filtration and desalination. The flow behavior and structural properties of water molecules through GO nanochannels are still under debate. In this work, molecular dynamics simulations were performed to explore the effects of interlayer spacing and oxidation degree of GO nanochannels on water transport. The results show that GO nanosheets have strong adsorption capacity. The adsorbed layer of water molecules on GO surface is thermodynamically stable and not easy to flow. When the interlayer spacing falls into the range of 0.6 ~ 1.0 nm, water molecules form into single or double adsorbed layers between two GO nanosheets. When the interlayer spacing is bigger than 1.2 nm, the other water layers in the middle of nanochannel become disordered. Taking the separation performance based on size exclusion into consideration, the most suitable interlayer spacing for water nanofiltration is approximate 1.2 nm, which has one flowing layer of water molecules. Oxygen-containing groups are unfavorable for water permeation, as more and more hydrogen bonds prevent water flowing on GO surface with the increasing oxidation degree. Our simulation results may help to improve the design of GO nanofiltration membranes for water treatment.
氧化石墨烯（GO）膜在水过滤和海水淡化应用中显示出巨大潜力。水分子通过GO纳米通道的流动行为和结构特性仍存在争议。在这项工作中，进行了分子动力学模拟，以探索GO纳米通道的层间距和氧化程度对水传输的影响。结果表明，GO纳米片具有很强的吸附能力。GO表面的水分子吸附层在热力学上是稳定的，不易流动。当层间距在0.6~1.0nm范围内时，水分子在两个GO纳米片之间形成单吸附层或双吸附层。当层间距大于1.2nm时，纳米通道中间的其他水层变得无序。考虑基于尺寸排阻的分离性能，水纳滤最合适的层间距约为1.2nm，此时有一层水分子流动。含氧基不利于水渗透，随着氧化程度的增加，越来越多的氢键阻止水在GO表面流动。我们的模拟结果可能有助于改进用于水处理的GO纳滤膜的设计。
