nisms for large non-Brownian particles, whereas Brownian The capture of charged Brownian particles in an idealized motion assists the capture of small submicron size particles. square array of cylindrical collectors has been studied using a finite Consequently, particles in the size range of one to several element method. In addition to varying the size of the cylindrical micrometers are most difficult to capture since the influence collectors and the porosity, the collector-particle interactions reof neither inertia nor the Brownian motion is significant.
sulting from van der Waals attraction and electrostatic repulsion
Due to its practical importance, numerous studies have have been considered. In a typical filtration process where the been conducted to model the filtration process during the particle capture is diffusion-limited, a critical value of surface past several decades (1-6). The most widely used approach potential appears to exist above which the filter coefficient deadopts an isolated spherical or cylindrical collector and carcreases rapidly. It is due to the insurmountable repulsive barrier between the particles and collectors. While the value of the critical ries out a particle trajectory analysis based on the flow field surface potential varies with the electrolyte concentration and the of an isolated collector to calculate the single-collector effi-Hamaker constant, it apparently corresponds to a common value ciency (2-10). Once the single-collector efficiency is calcuof about 10 kT for the height of the primary maximum of the lated, attempts are made to relate it with the capture effiinteraction potential. แญง 1997 Academic Press ciency of the overall collector assemblage (i.e., filter bed). Key Words: colloidal interactions; Brownian particles; periodic However, the adaptation of single-collector efficiency to the array of cylinders; filtration. overall assemblage is semitheoretical, at best, since the flow field which influences the single-collector efficiency can only be determined when the detailed structure (or array) of a two-step process: the transport of particles from the suspen-