Effect of a charged boundary on the electrophoresisof a colloidal particle

• Main Authors: Ming-Hong Ku, 古明弘
• Other Authors: 徐治平
• Format: Others
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/40940358543064716288

博士 === 國立臺灣大學 === 化學工程學研究所 === 93 === The electrophoretic behaviors of colloidal particles near a rigid, charged boundary are investigated through solving numerically the governing electrokinetic equations by a finite element method. Four types of system are considered: a sphere along the axis of a cylindrical pore, a sphere normal to a large disk/plane, and a short cylinder or two short cylinders along the axis of a cylindrical pore. Three kinds of charged conditions on particle surface are considered: constant surface potential, constant surface charge density, and charge-regulated model. Under the conditions of low surface potential and weak applied electric field, the electrophoretic mobility of a particle is evaluated by a superposition method. The influences of the key parameters of the systems under consideration on the mobility of a particle are investigated through numerical simulation. These include the charged conditions on a particle and on a boundary, the geometries of a particle and a boundary, the separation distance between a particle and a boundary or between two particles, and the thickness of double layer. Several interesting results are observed which are of both fundamental and practical significance. For instance, we show that the presence of a charged boundary can increase, decrease, or even change the direction of the movement of a particle. Also, the mobility of a particle may exhibit a local maximum as the thickness of double layer varies.