Electrokinetic motion of a spherical polystyrene particle at a liquid-fluid interface

Junyan Zhang; Yongxin Song; Dongqing Li

doi:10.1016/j.jcis.2017.09.020

Electrokinetic motion of a spherical polystyrene particle at a liquid-fluid interface

J Colloid Interface Sci. 2018 Jan 1:509:432-439. doi: 10.1016/j.jcis.2017.09.020. Epub 2017 Sep 7.

Authors

Junyan Zhang¹, Yongxin Song¹, Dongqing Li²

Affiliations

¹ Department of Marine Engineering, Dalian Maritime University, Dalian 116026, China.
² Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON N2L3G1, Canada. Electronic address: dongqing@uwaterloo.ca.

PMID: 28923740
DOI: 10.1016/j.jcis.2017.09.020

Abstract

Electrokinetic movement of spherical polystyrene particles at different liquid-fluid interfaces was experimentally investigated in this paper. A novel method was developed to place the particles rightly at the interfaces formed in a large plastic container. The velocity was measured by an optical microscope. The experimental results show that the particles (3, 5 and 10μm in diameter) at the water-air interface, water-dodecane interface and NaCl solution-air interface move in the opposite direction of the applied electric field. The magnitude of the particles' velocity increases linearly with the increase in the applied electric field. Moreover, for particles of the same size, the electrokinetic velocity at the liquid-fluid interfaces is larger than particles' electrophoretic velocity in the bulk liquid phase. Under the same electric field, however, the electrokinetic velocity of smaller particles at the liquid-fluid interfaces is larger than that of larger particles. Such results are attributed to the surface charges at the liquid-fluid interface and the particle-liquid interface.

Keywords: Electrokinetic movement; Liquid-fluid interface; Moving interface; Particle; Surface charges.