The presence of a boundary on the diffusiophoretic behavior of a particle is analyzed by considering the diffusiophoresis of a charged, finite cylindrical particle along the axis of an uncharged cylindrical pore filled with an electrolyte solution. Compared with the other similar geometries considered in the literature, the boundary effect is the most significant in the present geometry, thereby highlighting its importance. The influence of chemiphoresis arising from two types of double-layer polarization (DLP) and that of the electrophoresis effect coming from the difference in the ionic diffusivities on the diffusiophoretic behavior of a particle are discussed. We show that this behavior can be influenced both quantitatively and qualitatively by the boundary. This is because all of the relevant factors, including the DLP effect, the electrophoresis effect, the electric repulsive force between the particle and the co-ions outside its double layer, and the hydrodynamic drag all depend highly on the degree of the boundary effect, yielding profound and interesting behaviors that are not reported in other similar studies. For instance, if the electrolyte concentration is low, then a particle with a low surface potential (ca. 25 mV) tends to migrate to the low-concentration side, which occurs only when the surface potential is high (exceeds ca. 150 mV) in other geometry.
Relation:
The Journal of Physical Chemistry C 116(7), pp.4455-4464
