Electrokinetic ion transport at micro–nanochannel interfaces: applications for desalination and micromixing
Electrokinetic ion transport at micro–nanochannel interfaces: applications for desalination and micromixing
复制标题
DOI：
10.1007/s13204-019-01207-x
复制
发表时间：
2019-11
影响因子：
--
通讯作者：
Wei Liu;Yueting Zhou;P. Shi
中科院分区：
文献类型：
--
作者：
Wei Liu;Yueting Zhou;P. Shi
离子浓差极化（ICP）现象广泛存在于纳米通道/膜界面附近。由于其独特的离子选择性传输能力，ICP已被应用于海水淡化、分子预浓缩、生物分子分离等领域。本文主要研究缓冲离子在微纳通道界面的输运机理。本文提出了一个多物理场耦合模型，其中引入了固定表面电压的边界条件来描述纳米通道网络的作用。通过对比仿真验证了所提模型和计算过程的有效性。模拟结果与ICP实验结果的比较表明，该模型可以有效地描述电场的非线性分布和一个典型的涡对从流动现象。提出了一个传播离子耗尽区（IDZ）的解析标度律，理论分析和数值结果证实了它的存在。对于瞬态演化，IDZ在0.01 s <t< 0.1 s时，扩散作用为扩散，对流作用为扩散。此外，进行详细的研究，以阐明离子耦合等离子体脱盐机制。考察了缓冲液浓度、微通道网络长度、微通道高度、切向电场等因素对脱盐效果的影响。最后，所提出的研究证实，该装置也具有良好的潜力，作为一个微混合泵。利用非线性电动流可以实现中性粒子的快速混合，混合效率达到91%。研究结果为此类芯片的设计和优化以及其他相关应用提供了重要的指导和物理启示。
The ion concentration polarization (ICP) phenomenon occurs widely near nano-channel/membrane interfaces. Due to its extraordinary selective ion transport ability, ICP has been applied in many fields, such as desalination, molecular preconcentration and biomolecular separation. This paper is devoted to describing the transport mechanism of buffer ions at micro–nanochannel interfaces. Here, a multiphysics coupling model is proposed, where the boundary condition for the fixed surface voltage is introduced to describe the effect of nanochannel networks. The effectiveness of the proposed model and the calculation process is confirmed through comparative simulations. Comparing the simulations with experimental ICP results shows that the proposed model can effectively describe the nonlinear distribution of electric fields and a typical vortex pair from flow phenomena. An analytic scaling law for the propagating ion depletion zone (IDZ) is proposed, and a theoretical analysis and numerical results confirm its existence. For transient evolution, the IDZ spreads asdue to diffusion fort< 0.01 s and astdue to convection from 0.01 s <t< 0.1 s. Furthermore, detailed studies are performed to elucidate the ICP mechanism for desalination. The factors affecting desalination are investigated, including the buffer concentration, length and performance of the nanochannel network, height of the microchannel and the tangential electric field. Finally, the proposed research confirms that this device also has excellent potential as a micromixer pump. The rapid mixing of neutral particles can be realized using nonlinear electrokinetic flows with a mixing efficiency reaching 91%. The presented results provide some important guidance and physical insights into the design and optimization for this kind of chip and other related applications.