DETACHMENT OF SPHERICAL MICROPARTICLES ADHERING ON FLAT SURFACES BY HYDRODYNAMIC-FORCES

The adhesion and detachment of spherical glass particles from a flat g lass surface are studied experimentally and theoretically. Adhesion is found to be strongly dependent on pH through modification of surface characteristics as well as through the imposition of electrostatic rep ulsion, which may prevent close approach of the adhering surfaces. A t heoretical analysis of the detachment mechanism for smooth and rough s urfaces is also presented. The experimentally found dependence of hydr odynamic forces on particle size, corroborated by the theoretical anal ysis, suggests that a rolling mechanism is responsible for detachment and that roughness at the submicroscopic level plays a decisive role. (C) 1995 Academic Press, Inc.