Zheng Zhi, Hansford Derek J, Conlisk Albert T
Biomedical Engineering Center, The Ohio State University, Columbus 43210-1107, USA.
Electrophoresis. 2003 Sep;24(17):3006-17. doi: 10.1002/elps.200305561.
In this work, the effect of multivalent ions on electroosmotic flow is investigated for multiple electrolyte components. The cases studied include incorporating Ca2+ and HPO4(2-) and other monovalent ions, such as K+ and H2PO4-, into an aqueous NaCl solution. The governing equations are derived and solved numerically. The boundary conditions for the governing equations are obtained from the electrochemical equilibrium requirements. In comparison with monovalent ions, the results show that in micro- and nanochannels having fixed surface charges, multivalent counterions, even in very small amounts, reduce electroosmotic flow significantly, while the multivalent co-ions have little effect on the electroosmotic flow. Due to the enhanced ion-wall interactions multivalent counterions compose the majority of ions in the electric double layer (EDL), causing a decrease of net charge at the surface.
在这项工作中，研究了多价离子对多种电解质组分电渗流的影响。所研究的情况包括将Ca2+和HPO4(2-)以及其他单价离子（如K+和H2PO4-）加入到NaCl水溶液中。推导了控制方程并进行了数值求解。控制方程的边界条件是根据电化学平衡要求得到的。与单价离子相比，结果表明，在具有固定表面电荷的微通道和纳米通道中，即使是极少量的多价反离子也会显著降低电渗流，而多价同离子对电渗流的影响很小。由于离子与壁面相互作用增强，多价反离子在双电层（EDL）中占离子的大部分，导致表面净电荷减少。
