EFFECTS OF MAGNETIC-FIELDS ON STABILITY OF NONMAGNETIC ULTRAFINE COLLOIDAL PARTICLES

Effects of exposure to a magnetic field on the stability of nonmagnetic colloidal particles, such as ultrafine polystyrene latex and SiO2 particles in electrolyte solutions, were examined by measuring the rapid coagulation rate constant on a low-angle light-scattering apparatus. It was found that the rapid coagulation rate does depend on the magnetic flux density and the duration of magnetic exposure, even though the magnetic flux density is not high, and that the degree of the magnetic effect depends on the particle size and ions in the medium. It is especially interesting to find that the magnetic effect remains for at least 143 h after the magnetic exposure is completed. It is postulated that these effects are mainly attributable to some alteration of the structure of water molecules and ions adsorbed on the particle surface with the magnetic exposure. © 1992.