PARTICLE ADHESION ON GELATIN-COATED GLASS SURFACES

The adhesion phenomena of monodispersed spherical hematite particles on gelatin-coated glass beads were evaluated using the packed column technique and compared with the same system in the absence of the protein. Uptake is observed when the collector beads, with or without gelatin, and the hematite particles have opposite signs of charge, although coating lowers the particle deposition rate and enhances the multilayer attachment. Furthermore, hematite particles are bound irreversibly to the gelatin-covered collector, whereas they can be fully removed from the clean glass. In either case the surface charge of interacting surfaces must be altered by rinsing the column with solutions of appropriate pH in order to cause repulsion. This behavior suggests that the interaction between hematite and glass is affected by physical forces only, whereas in the presence of gelatin, chemical bonds are formed between the particles and the substrate. (C) 1995 Academic Press, Inc.