title: Electrophoretic mobility of oil droplets in electrolyte and surfactant solutions.
abstract: Electrophoretic mobility of oil droplets of micron sizes in PBS and ionic surfactant solutions was measured in this paper. The experimental results show that, in addition to the applied electric field, the speed and the direction of electrophoretic motion of oil droplets depend on the surfactant concentration and on if the droplet is in negatively charged SDS solutions or in positively charged hexadecyltrimethylammonium bromide (CTAB) solutions. The absolute value of the electrophoretic mobility increases with increased surfactant concentration before the surfactant concentration reaches to the CMC. It was also found that there are two vortices around the oil droplet under the applied electric field. The size of the vortices changes with the surfactant and with the electric field. The vortices around the droplet directly affect the drag of the flow field to the droplet motion and should be considered in the studies of electrophoretic mobility of oil droplets. The existence of the vortices will also influence the determination and the interpretation of the zeta potential of the oil droplets based on the measured mobility data.
authors.affiliation: Department of Marine Engineering, Dalian Maritime University, Dalian, P. R. China.
authors.forename: Jiachen
authors.initials: J
authors.lastname: Wuzhang
authors.affiliation: Department of Marine Engineering, Dalian Maritime University, Dalian, P. R. China.
authors.forename: Yongxin
authors.initials: Y
authors.lastname: Song
authors.affiliation: Department of Marine Engineering, Dalian Maritime University, Dalian, P. R. China.
authors.forename: Runzhe
authors.initials: R
authors.lastname: Sun
authors.affiliation: Department of Marine Engineering, Dalian Maritime University, Dalian, P. R. China.
authors.forename: Xinxiang
authors.initials: X
authors.lastname: Pan
authors.affiliation: Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON, Canada.
authors.forename: Dongqing
authors.initials: D
authors.lastname: Li
mesh_terms: D004560:Electricity; D004573:Electrolytes / Q000737:chemistry*; D004586:Electrophoresis / Q000379:methods*; D009821:Oils / Q000032:analysis / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D004573:Electrolytes; D009821:Oils; D013501:Surface-Active Agents
keywords: Charge redistribution; Droplet electrophoresis; Electrophoretic mobility; Ionic surfactant; Vortex interaction