正渗透过程中水和离子在碳纳米管中的传递行为研究

摘要

利用分子动力学模拟探究了在不同尺寸单壁纳米碳管(例如：CNT(6,6)、CNT(7,7)、CNT(8,8)、CNT(9,9)、CNT(10,10)、CNT(11,11)等)所构筑的正渗透膜中，以不同浓度氯化钠溶液(例如：2.5、3.75、5 mol⋅L-1等)作为汲取液时，水和离子的正向和反向传递行为。模拟得到水通量随时间的演变情况以及汲取液中离子在纳米碳管膜中的正向和反向运动轨迹等。模拟结果表明，随着纳米碳管直径的增加，水通量随时间的变化趋势主要与管径以及水分子在管中的扩散速率有关，而汲取液中离子的反向传递则取决于膜两侧的浓度差以及离子在管口处所面对的能垒。%The influence of carbon nanotube (CNT) dimension (CNT(6,6), CNT(7,7), CNT(8,8), CNT(9,9), CNT(10,10) and CNT(11,11)) and NaCl concentrations (2.5mol⋅L-1, 3.75 mol⋅L-1 and 5 mol⋅L-1) on forward and reversed transport behaviours of water molecules/ions in forward osmosis membranes was explored by molecular dynamic computer simulation. Based on the computer simulation results, the relevant information inside different CNT membranes, including the evolution of water flux with time and the forward and reversed motion of ions in carbon nanotubes were acquired. The former one is closely related to the diameter of carbon nanotubes and the diffusion rate of water in the carbon nanotubes. Furthermore, the reversed penetration of ions in the draw solution depends on the concentration difference between the two sides of the membrane, and the ion energy barrier at the entrance of carbon nanotubes.