ON THE KINETICS OF PARTICLE REENTRAINMENT FROM SURFACES

A kinetic model of particle reentrainment is presented and compared with data from industrial high purity gas systems and with controlled experiments using Latex particles of 0.4-1 μm. The model describes reentrainment as a first order reaction, analogous to molecular desorption from an inhomogeneous surface, with a rate constant a(F) = A exp(-F) (F = adhesion force/removal force). The rate equation is integrated over a model distribution of F, giving analytical solutions for the concentration of particles on the surface and in the gas stream as a function of time. For sufficiently broad initial adhesion force distributions, both surface concentration and gas concentration decay inversely proportionally to time, similar to Reeks et al. The model agrees well with experimental data and also explains observed systematic deviations of the data from the 1/t law. Based on the model, rate constants A are inferred, and the widths of adhesion force distributions and the size of initial surface particle populations are estimated.