FLOW-INDUCED SURFACE BLOCKING EFFECTS IN ADSORPTION OF COLLOID PARTICLES

Localized, irreversible adsorption of interacting colloid particles fr om well-defined hows was studied experimentally and theoretically. The impinging-jet cells were used for creating the axisymmetric and plane -parallel (slot) laminar flows, enabling a direct microscope determina tion of particle adsorption kinetics. Monodisperse suspension of polys tyrene latex particles was used for measuring the influence of how int ensity (shear rate) on particle adsorption kinetics. The experimental data were interpreted in terms of the approximate analytical predictio ns derived using the random sequential adsorption (RSA) approach valid for low and moderate surface concentrations. For an arbitrary range o f surface concentrations the general sequential Brownian dynamics (SBD ) simulation method was used to interpret the experimental data. It wa s found that these theoretical methods reflected well the characterist ic features of the adsorption experiments, especially the significant decrease of adsorption kinetics for higher how shear rates and low ion ic strengths caused by the hydrodynamic scattering effect (HSE). Due t o this effect, the surface-blocking phenomena for spherical particles become analogous to elongated non-spherical particles under no-how ads orption conditions. (C) 1995 Academic Press, Inc.