Video Processing Electrophoretic Measurements under High Electric Fields for Sub-millimeter Particles in Oil

Electrokinetic properties such as the mobility, surface charge, and zeta potential of sub-millimeter particles are vital parameters in various industrial applications. Their measurement and control in aqueous media have been extensively studied. However, despite their growing importance, the electrokinetic properties of organic solvents have not been studied as thoroughly as those of aqueous media. An electrophoresis cell with a microscope monitor was designed for the electrokinetic studies of sub-millimeter particles in cyclohexane, which is a solvent with very low permittivity. The movement of large particles in the range of 4 similar to 478 mu m was successfully traced under a strong electric voltage up to 1100 V, even without the addition of surfactants. The particle sizes were at least 300 times larger than those reported previously. By applying electric fields up to 55 kV/m, the electrophoretic mobilities were measured to be of the order of 10(-9) to 10(-7) m(2)/V.s through image processing of the recorded particle movement. Five organic sub-millimeter particles had charge densities in the range of -3.5 similar to 4.4 e/mu m(2), and polyethersulfone particles showed extremely high mobilities. The surface charge of organic and inorganic particles is mainly generated by the dissociation of hydroxide groups or by the protonation to surface Lewis base oxygen atoms.

Automated summary

This study designed an electrophoresis cell to investigate the electrokinetic properties of sub-millimeter particles in organic solvents. The results showed that the movement of large particles in cyclohexane, a solvent with low permittivity, could be traced even without surfactants. The measurements revealed that organic sub-millimeter particles had significant charge densities and polyethersulfone particles exhibited extremely high mobilities.