Boundary effects on diffusiophoresis motion of colloidal spheres

• Main Authors: Chun-Yu Shih, 施俊羽
• Other Authors: Keh-Chyang Lee
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/37327123534943839860

碩士 === 國立臺灣大學 === 化學工程學研究所 === 96 === The diffusiophoretic behavior of a colloidal sphere, at different boundary effect is investigated in this study. Two kinds of representative cases are discussed here. One is that the diffusiophoresis of a spherical particle in a spherical cavity, and the other one is that the diffusiophoresis of a spherical particle normal to a free surface. Except for constant surface potential, the effect of charge regulation is also considered here. The restriction of low zeta potential is extend to the case of arbitrary zeta potential, and solved simultaneously by pseudo-spectral method. We find that an electrophoretic effect is generated due to an induced electric field along the direction of the bulk concentration gradient when the diffusion velocity of cations is different from that of anions. This induced electric filed can affect the motion of the particle in accordance with the charged condition on the particle. Furtermore, the diffusiophoretic velocity of the particle reaches a local maximum with the increase of . The steric hindrance for the fluid flow also becomes serious if the volume fraction of particles gets higher. As for the case of free surface, the free surface boundary can deform the double layer around the particle, and thus the diffusiophoresis of the particle becomes more complicated than that before.