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建立了一种两端带有缓冲液池的纳米通道流体电动输运的分子动力学模型,仿真了纳米通道中的离子输运过程.结果表明,纳米通道的带电表面会引起双电层(EDL)域中反号离子的富余及同号离子的衰减,在外加电场作用下,通道中正负离子的定向移动将产生稳定的电泳电流,该电流主要由EDL域中占主导地位的反号离子的定向移动产生;当EDL域与外界有离子交换时,电场的作用会导致EDL域内Na+和Cl?离子数量的减少,平衡后,EDL域的电中性将受到破坏,对外显示的电性取决于表面电荷的特性;EDL域内离子分布与连续理论预测的结果相差很大,如壁面附近Na+浓度峰值远低于理论预测值;提高表面电荷密度可以有效提高反号离子在通道中的传输效率,同时降低同号离子的传输效率.仿真结果证实了经典扩散双电层理论模型无法准确描述纳米通道中的离子分布,探明了相关实验现象的产生机理以及纳米通道中离子传输效率与表面电荷密度的关系,为纳米泵的设计及应用提供了理论依据.
A molecular dynamics model of nanochannel fluid transport with buffer pool at both ends was established to simulate the ion transport process in the nanochannel.The results show that the charged surface of the nanochannel can cause the electric double layer (EDL ) Domain of the counter ion surplus and the same number of ions decay in the external electric field, the positive and negative channels in the directional movement will produce a stable electrophoretic current, the current mainly by the EDL domain dominated counter ion orientation When the EDL domain is ion exchanged with the outside world, the action of the electric field will lead to the decrease of the amount of Na + and Cl? Ions in the EDL domain. After the balance, the electric neutrality in the EDL domain will be destroyed, and the electric property of the external display depends on the surface The distribution of ions in the EDL domain is different from that predicted by the continuous theory. For example, the peak value of Na + concentration near the wall is much lower than the theoretical value. Increasing the surface charge density can effectively increase the transfer efficiency of the counter ion in the channel, The transfer efficiency of the same number of ions.The simulation results confirm that the classical model of the diffusion electric double layer can not accurately describe the ion distribution in the nanochannels and the correlation of the experimental phenomena Generation mechanism and the relationship between ion transport efficiency and surface charge density in nanochannels provide a theoretical basis for the design and application of nanometer pump.