Irreversible adsorption of colloids and proteins at heterogeneous surfaces

Irreversible adsorption of colloid particles at heterogeneous surfaces was studied theoretically. In contrast to previous models, the dimension of the adsorption sites having the shape of circular discs, was comparable with the size of adsorbing spheres. Adsorption was assumed to occur if the sphere contacted the disc only. Numerical simulation of the Monte-Carlo type enabled one to determine particle flux, adsorption kinetics and jamming coverage as a function of the site density (coverage) and the size ratio particle/site, denoted by lambda. It was demonstrated that adsorption kinetics and the jamming coverage increased significantly, at a fixed site density, when lambda increased, i.e., for larger particle to site size ratio. It was also proven that the results derived from previous model elaborated for negligible site dimensions are valid only if lambda > 10.