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Electrophoretic mobility does not always reflect the charge on an oil droplet
- Source :
- Journal of Colloid and Interface Science, 318(2), 477-486. ACADEMIC PRESS INC ELSEVIER SCIENCE
- Publication Year :
- 2008
- Publisher :
- ACADEMIC PRESS INC ELSEVIER SCIENCE, 2008.
-
Abstract
- Electrophoresis is widely used to determine the electrostatic potential of colloidal particles. Oil droplets in pure water show negative or positive electrophoretic mobilities depending on the pH. This is commonly attributed to the adsorption of hydroxyl or hydronium ions, resulting in a negative or positive surface charge, respectively. This explanation, however, is not in agreement with the difference in isoelectric point and point of zero charge observed in experiment. Here we present molecular dynamics simulations of oil droplets in water in the presence of an external electric field but in the absence of any ions. The simulations reproduce the negative sign and the order of magnitude of the oil droplet mobilities at the point of zero charge in experiment. The electrostatic potential in the oil with respect to the water phase, induced by anisotropic dipole orientation in the interface, is positive. Our results suggest that electrophoretic mobility does not always reflect the net charge or electrostatic potential of a suspended liquid droplet and, thus, the interpretation of electrophoresis in terms of purely continuum effects may need to be reevaluated. (C) 2007 Elsevier Inc. All rights reserved.
- Subjects :
- IONS
MOLECULAR-DYNAMICS SIMULATIONS
Hydronium
SURFACE
Surface Properties
Static Electricity
electrokinetic phenomena
Analytical chemistry
POTENTIALS
LIQUID-VAPOR INTERFACE
Heptanes
Biomaterials
Physics::Fluid Dynamics
chemistry.chemical_compound
zeta potential
water structure
Colloid and Surface Chemistry
SYSTEMS
DEFORMATION
Electric field
AQUEOUS-SOLUTIONS
Zeta potential
computer simulation
WATER
Surface charge
Point of zero charge
Chemistry
molecular dynamics
Surfaces, Coatings and Films
Electronic, Optical and Magnetic Materials
Electrophoresis
Isoelectric point
Models, Chemical
Chemical physics
Oil droplet
electrophoresis
Adsorption
HYDROCARBONS
Hydrophobic and Hydrophilic Interactions
Oils
Subjects
Details
- Language :
- English
- ISSN :
- 00219797
- Volume :
- 318
- Issue :
- 2
- Database :
- OpenAIRE
- Journal :
- Journal of Colloid and Interface Science
- Accession number :
- edsair.doi.dedup.....b06073a03bd667dc03c7d2974d6c65ed