KINETICS OF COLLOID DEPOSITION ONTO HETEROGENEOUSLY CHARGED SURFACES IN POROUS-MEDIA

A general theoretical approach for the calculation of colloid depositi on rate onto heterogeneously charged surfaces is presented. Patchwise and random distribution models are used to quantitatively describe sur face charge heterogeneity and its effect on the kinetics of colloid de position. It is shown that unfavorable surfaces with only minor amount s of charge heterogeneity have particle deposition rates that are orde rs of magnitude larger than similar surfaces having no charge heteroge neity. Furthermore, the sensitivity of particle deposition rate to sol ution ionic strength decreases as the degree of surface charge heterog eneity increases. Parameters characterizing the surface charge heterog eneity of collectors in porous media are identified from experimental data of colloid deposition by using the inverse procedure of parameter estimation. These heterogeneity parameters can be used in conjunction with current theories of particle deposition to explain experimental results of colloid deposition rates under chemical conditions that are unfavorable for particle deposition.