KINETICS OF COLLOID PARTICLES DEPOSITION UNDER THE INFLUENCE OF GRAVITY

Kinetics of irreversible deposition of interacting colloid particles a t solid/liquid interfaces has been investigated experimentally using t he direct microscope observation technique coupled with an image analy sing system. The new sedimentation cell enabled to study in real time both the number of particles deposited at a given surface area and the distribution of particles characterized in terms of the pair correlat ion function. Using the monodisperse colloid suspensions of melamine-f ormaldehyde latex particles with specific density of 1.5 g/cm(3) and t he micrometer size range the effect of gravity has been evaluated quan titatively. It was found that particle deposition rate under gravity w as considerably enhanced in comparison with the previously studied cas e of diffusion affected adsorption when the random sequential adsorpti on (RSA) mechanism was valid. Accordingly, the experimental results co uld be interpreted in terms of the ballistic adsorption model using th e effective hard particle concept rather than in terms of the RSA mode l.