Numerical study on electrophoretic motion of hydrophobic nano-cylinder particles

Electrophoresis of nanoparticles due to its wide range of applications like separation of bioparticle and drug delivery has a crucial role in Micro andNanofluidics. In the conventional theory of electrokinetic phenomena, a no-slip boundary condition is assumed for the surface of a movingparticle. But the no-slip condition is only valid when there is a strong bond between molecules of a particle and electrolyte solution. In other cases, the Navierslip condition replaces the no-slip condition as the proper choice for the particle’s boundary condition. In this paper, we investigated the effect of ahydrophobic surface on the electrophoretic motion of a cylindrical nanoparticle. PNP-NS equations with modified boundary conditions and a wide range ofslip length, surface charge density, and concentration of electrolyte solution were solved numerically. For each point, electric and hydrodynamic stresses were calculated, and the particle’s mobility was obtained through an iterative method. According to the results, in all cases, by enhancing slip length, theelectrophoretic mobility increases, and the hydrodynamic stress decreases. Because of the conductance effect, the influence of hydrodynamicslip in particles with a thick electric double layer ismore significant than particles with a thin electric double layer. Also, our study showed that byincreasing concentration of electrolyte, electrophoretic mobility of hydrophobic nanocylinder particles reduces.

Keywords:

Electrophoresis , Hydrophobicity , Cylindrical , nanoparticle , Electric double layer , Numerical simulation