EFFECT OF PARTICLE-SIZE ON THE KINETICS OF PARTICLE DEPOSITION UNDER ATTRACTIVE DOUBLE-LAYER INTERACTIONS

The effect of particle size on the kinetics of particle deposition in the presence of attractive double layer interactions has been studied theoretically and experimentally. Particle deposition experiments were carried out with several model suspensions of positively charged latex particles and negatively charged glass beads using the packed bed column technique. The model particles used in the deposition experiments covered a wide size range, from 0.08 to 2.51 mum. Experimental deposition rates were compared to theoretical predictions based on a numerical solution of the convective diffusion equation with colloidal, hydrodynamic, and gravitational forces fully incorporated. Theoretical and experimental results reveal that the enhancement in particle deposition rate (i.e., the deposition rate in the presence of double layer interaction divided by the rate in the absence of double layer interaction) is dependent on particle size. At low ionic strengths, the enhancement in deposition rate passes through a maximum as the particle size increases. This maximum corresponds to particles with a size around 1 mum. It is also concluded that this maximum is determined by the interplay between the size of the particles and the range of the attractive double layer interactions. (C) 1994 Academic Press, Inc.