Dynamics of colloidal particles in the vicinity of an interacting surface

Abstract

A Brownian dynamics method has been pursued to study the diffusive motion of a colloid particle leading to its deposition at an interacting surface. The present study considers two models for the diffusion boundary layer. In model I, the layer is bounded by a pair of absorbing surfaces, one real and the other virtual. The real surface has both static and hydrodynamic interactions with the particle, but the virtual surface has no such interactions, serving merely as an absorbing boundary. In model II, the interaction characteristics of the real surface are the same as in model I, but the virtual surface is a reflecting boundary. Calculation of the mean times and probabilities of the particle absorption has been carried out for a number of particle-surface potential-energy functions. The results are in excellent agreement with those derived from the application of the first-passage-time approach to the two models. The computed data are used to obtain values of the rate constant for the process of particle deposition. For a given potential function, the rate constant is found not to differ greatly for the two models, implying that the results are almost model-independent. The increase in the depth and range of the potential function is found to result in significant changes in the rate constant.