AIChE Journal, Vol.40, No.11, 1876-1891, 1994
Colloidal Gel-Filtration - Experiment and Theory
The filtration of colloidal gels, consisting of octadecyl-coated silica spheres in hexadecane, is examined experimentally using CAT scanning. A number of interparticle strengths are explored, with significant differences in qualitative behavior relative to the filtration of stable dispersions. For stiff gels, the transmission of stresses from the cell wall to the dispersion results in a fracturing phenomenon during consolidation on a length scale substantially larger than the particle size. For more pliant gels, the radial propagation of stress is more local to the wall region and gravitational effects play a prominent role. The existing theory of network consolidation is compared against our experimental results for pliant gels, independent of the form of the constitutive functions for the sedimentation velocity and yield stress. Though our measurements seem consistent with the theory at early times, deviations at later moments question whether a compressive yield stress is actually present.
Keywords:SILICA PARTICLES;FLOCCULATED SUSPENSIONS;CATALYZED-HYDROLYSIS;PRESSURE FILTRATION;GROWTH-MODEL;KYNCH THEORY;DISPERSIONS;CONSOLIDATION;SEDIMENTATION;PRECIPITATION