Computer simulation of steady-state diffusion-controlled reaction rates in dispersions of static sinks: Effect of sink sizes

Abstract

The steady state diffusion-controlled reaction or trapping rate k2 in binary mixtures of impenetrable, nonoverlapping static sinks or traps are determined through random-walk simulations. The simulations are carried out using the first passage time technique. Exact values of the reaction rate k2 are obtained as a function of the total sink volume fraction φ, sink size ratio β, and sink number fraction xA. The reaction rate k2 is found to increase with increasing surface area of the sinks. Specifically, for dispersions at low volume fraction φ and small values of β, we observe from our data that the ratio of the reaction rate in a binary sink dispersion to that of the monodisperse system is directly proportional to the square of the ratio of the specific surface areas of the two systems. In addition, it is found that the quantity l=〈R3〉/〈R2〉 serves as an appropriate scaling parameter for the reaction rate k2.