Department of Chemical Engineering, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132, Indonesia; Research Center for Nanosciences and Nanotechnology, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132, Indonesia.
Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States.
Adv Colloid Interface Sci. 2020 Oct;284:102269. doi: 10.1016/j.cis.2020.102269. Epub 2020 Sep 11.
Electromembrane processes including electrodialysis (ED) and related processes are usually limited by diffusion transport of ions from a bulk solution to ion exchange membranes. The diffusion limited current (DLC) occurs when the concentration at membrane surfaces vanishes and approaches zero. Increasing the applied potential difference above this point has no substantial effect on ion transport and causes operational problems such as low current efficiency, high energy consumption, and mineral scaling. However, it is evident from numerous studies that operating at overlimiting current (OLC) is possible and allows one to enhance the mass transfer of an electromembrane process. While OLC is sometimes possible by electrochemical means, such as water splitting or current induced membrane discharge, it has been found that exotic ion transport mechanisms, such as ion concentration polarization in micro/nanofluidic system, deionization shock waves, and ionic bridges, can provide novel electrokinetic means of achieving OLC. In this paper, these novel ionic separation mechanisms and their role in enhanced current transfer are reviewed in the context of emerging electromembrane processes, such as shock ED and electrodeionization (EDI).
电膜过程包括电渗析 (ED) 和相关过程，通常受到离子从主体溶液扩散到离子交换膜的限制。当膜表面的浓度消失并趋近于零时，就会出现扩散限制电流 (DLC)。在超过这个点施加更高的电位差对离子传输没有实质性影响，反而会导致操作问题，如低电流效率、高能耗和矿物结垢。然而，从许多研究中可以明显看出，在过限电流 (OLC) 下运行是可行的，并允许增强电膜过程的传质。虽然通过电化学手段，如水电解或电流诱导膜放电，有时可以实现 OLC，但已经发现，奇异的离子传输机制，如微/纳米流体系统中的离子浓度极化、去离子冲击波和离子桥，可以提供实现 OLC 的新电动手段。在本文中，这些新颖的离子分离机制及其在增强电流传递中的作用将在新兴的电膜过程（如冲击电渗析和电极去离子化 (EDI)）的背景下进行回顾。
