Effect of electrostatic interaction on deposition of colloid on partially covered surfaces: Part II. Results of computer simulations

Abstract

We study random sequential adsorption (RSA) of electrostatically interacting colloid particles using the new simulation approach described in Paper I [P. Weroński, Effect of electrostatic interaction on deposition of colloid on partially covered surfaces. Part I. Model formulation, Coll. Surf. A, doi:10.1016/j.colsurfa.2006.08.018]. Numerical simulations are performed according to this curvilinear trajectory RSA model to determine the available surface function, jamming coverage, and pair-correlation function of the larger particles. The effect of the particle size ratio, electrolyte ionic strength, and the small-particle surface coverage on the large-particle deposition is demonstrated. The numerical results are tested using the two-dimensional (2D) scaled-particle theory, with a modification for the sphere geometry and electrostatic interaction, exploiting the extension of the effective hard-particle approximation to bimodal systems. The effect of electrolyte concentration on the effective minimum particle surface-to-surface distance is presented, too. The numerical results are compared with the results obtained using two older approaches, the 2D and three-dimensional (3D) RSA models. The study suggests that the formula stemming from the scaled-particle theory provides a good approximation in the low surface coverage limit. The results obtained with the 3D and curvilinear trajectory models indicate that large-particle/substrate attractive interaction significantly reduces the kinetic barrier to large, charged-particle adsorption at a surface precovered with small, like-charged particles. The available surface function and jamming-coverage values predicted using the simplified 3D and the more sophisticated curvilinear trajectory models are similar, while the results obtained with the 2D model differ significantly. The pair-correlation function suggests different structures of monolayers obtained with the three models. Results of this research clearly suggest that the extended curvilinear trajectory RSA approach can fruitfully be exploited for numerical simulations of colloid-particle adsorption at precovered surfaces, allowing the investigation of soft-particle systems.