Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Republic of Korea.
Lab Chip. 2018 Jun 12;18(12):1713-1724. doi: 10.1039/c8lc00132d.
It has been observed that colloidal particles are anomalously repelled from the interface of nanoporous materials and water by up to hundreds of micrometers even if there is no additional external field present. Recently, the physical origin of this anomalous repulsion has turned out to be diffusiophoretic migration triggered by an ion exchange process through the interface. Since the repulsive force is induced by a salt gradient only, the phenomenon can be applied to a microscale water purification platform without the need for any external power sources. In this work, we suggest a micro/nanofluidic device for continuous water purification utilizing long-range diffusiophoretic migration around ion exchangeable surfaces. An ion concentration boundary layer was characterized by the Sherwood number (Sh) which is a key dimensionless number to describe the purification process. Depending on Sh, we have theoretically and experimentally demonstrated that long-range diffusiophoretic exclusion can be used for continuous water purification. Finally, our platform can be used as a highly energy-efficient and portable water treatment option for operations such as purification, disinfection, water softening, etc.
已经观察到胶体颗粒即使在没有额外外部场存在的情况下，也会被纳米多孔材料和水的界面反常排斥数百微米之远。最近，这种反常排斥的物理起因被证明是通过界面进行的离子交换过程引发的扩散迁移。由于排斥力仅由盐梯度引起，因此该现象可应用于微尺度水净化平台，而无需任何外部电源。在这项工作中，我们提出了一种微纳流控装置，用于利用可交换离子表面的长程扩散迁移进行连续水净化。离子浓度边界层由舍伍德数（Sh）来表征，Sh 是描述净化过程的关键无量纲数。根据 Sh，我们从理论和实验上证明了长程扩散排斥可用于连续水净化。最后，我们的平台可用作高效节能且便携的水处理选项，可用于净化、消毒、软化水等操作。
