Deposition and release of colloidal particles in porous media

The interaction of colloidal carboxylated latex particles with a packed bed of glass beads is studied by means of chromatographic techniques. For these negatively charged surfaces we find strong evidence of particle attachment as well as detachment processes. In particular, the rate constants of the two processes are measured from the particle breakthrough curve of a pulse input. Ionic strength is found to have profound effect on these processes. Upon increasing ionic strength, the deposition rate constant crosses over from the slow to the fast aggregation regime, whereas its release counterpart shows the opposite trend, with their crossing-over concentrations being the same. The DLVO theory with particle-beads interactions is used to explain these findings qualitatively.