Electrokinetic transportation and differentiation of copper and aluminum particles in oil with an oil-water interface

Abstract

The transportation of metal particles in oil has numerous applications in industrial areas. Under electric field, the electroosmotic flow of the oil-water interface can be generated; therefore, the electrokinetic transportation of the metal particles is expected by attaching the metal particles from the oil phase into the oil-water interface. In this paper, an oil sample containing metal particles was placed onto an aqueous electrolyte solution and let the metal particles settle at the oil-water interface by gravity sedimentation. The contact angles of the metal particles at the oil-water interface were measured first. Subsequently, the electrokinetic transportation of metal particle was investigated by applying a direct electric field along the oil-water interface. The experimental results indicate that at the interface, the metal particle immersed totally in the oil phase. The electrokinetic motions of the metal particles can be generated in the direction opposite to the applied electric field. The velocity of the particle is independent of particle’s diameter, increases with the decrease in particle’s mass density and with the increase of the applied electric field. Aluminum and copper particle differentiation was achieved by using a so-called specific sized-velocity. This transportation method demonstrated in this paper opens opportunities in electrical manipulation of metal particles in oil for the fields of mechanical wear debris detection.