单层多孔石墨烯膜反渗透特性的分子动力学研究

Molecular Dynamics Study on Reverse Osmosis Properties of Monolayer Porous Graphene Membranes

采用经典分子动力学方法研究了多孔石墨烯膜的反渗透特性,揭示了盐溶液质量浓度、外部压强、孔面积和孔形状对多孔石墨烯膜反渗透特性的影响规律。结果表明:脱盐率随着盐溶液质量浓度的增加而增大;水通量随着外部压强与孔面积增加而增大,但同时脱盐率随着外部压强与孔面积增加而降低;孔形状越趋近于圆形,水分子透过多孔石墨烯膜的能障越小,说明水分子越容易通过多孔石墨烯膜。相同脱盐率情况下,该模型中的水通量结果比实验报道中聚酰胺复合反渗透膜的水通量高2个量级。因此,多孔石墨烯膜将有可能在海水淡化和功能渗透膜领域发挥重要作用,研究结果将为基于石墨烯材料的反渗透膜研发设计提供一定的理论参考。

The reverse osmosis properties of the porous graphene membranes were researched by the classic molecular dynamics method. The effect laws of the salt solution mass concentration, external pressure, pore area and pore shape on the reverse osmosis properties of the porous graphene membrane were revealed? The results demonstrate that the salt rejection increases with the increase of the salt solution mass concentration. With the increases of the external pressure and the pore area, the water flux of the porous graphene membrane increases, but at the same time, the salt rejection decreases.The energy barrier of water molecules passing through the porous graphene membrane decreases when the pore shape tends to be round, indicating that the water molecules are easier to pass through the porous graphene membrane. Under the same salt rejection, the water flux of the porous graphene membrane in this model is 2 orders of magnitude higher than that of the composite polyamide reverse osmosis membranes reported in the experimental research. Therefore, porous graphene membranes may play an essential role in the fields of sea water desalination and functionalized osmotic membranes. The research results can provide some theoretical references for the design and development of porous graphene-based reverse osmosis membranes.